Submitted February 4^th 2011 /  Accepted July 29^th 2011

Abstract

Background. Evidence from regions where there have been severe dietary restriction suggests that individuals in utero during periods of starvation may subsequently be at increased risk of schizophrenia. Because Ireland was the location of a major nineteenth century famine an attempt has been made to determine whether any such evidence for famine/schizophrenia association can be found.

Method. The data used derive mainly from the Annual Reports on the District, Criminal and Private Lunatic Asylums supplied by the Inspectors of Lunacy in Ireland for the relevant years.  Nineteenth century diagnostic labels have been adjusted to conform to schizophrenia as currently understood. Evidence relating to a possible schizophrenia increase in famine-related emigrants is examined.

Results. There was an increase in first admission rates for schizophrenia of 85.7% from 1860 to 1875. Admissions for other disorders, chiefly melancholia, also increased. Similar admission increases were evident in other jurisdictions over the same period. Data relating to the mental health of famine – migrating Irish are sparse and of difficult interpretation.

Conclusion. The evidence from available data sources attempting to link the Irish famines of the 1840s with a subsequent increase in the incidence of schizophrenia is equivocal and inconclusive.

Key words: Schizophrenia, famine, 19^th century Ireland.

Introduction                                                                                                      

The impact of famine conditions on the human embryo has been a matter of study. For example maternal under-nutrition may result in cephalopelvic disproportion resulting in increased birth complications following maternal rickets due to insufficiency of vitamin D.¹ Low fertility, decreased birth weight and the survival of underweight and premature infants as a consequence of improved obstetric care may lead to substantial health consequences later in life. These include developmental retardation or abnormalities. For example there is mounting evidence that schizophrenia (as well as autism and intellectual disability) may be a developmental disorder associated with a variety of environmental/gene interactions, such as maternal pre-natal infection in genetically susceptible persons, resulting in abnormalities of synaptic formation and maintenance and of mechanisms of neurotransmission, manifesting themselves in cognitive, affective and perceptual anomalies.² Among other suspect relevant environmental traumas is maternal under-nutrition.³

The occurrence of two relatively recent famines has led to a natural experiment of their effect on neurodevelopment. The first was the Dutch Winter Hunger and the second the Great Leap Forward Chinese famine.                                                                                       

The Dutch famine occurred at a specific time and geographical region and records were able to document the timing and extent of the resultant under-nutrition. The relevant circumstances were that towards the closing phase of World War 2 the Dutch population attempted to assist the Allied advance. In retaliation the German occupation authority imposed a ban on the importation of food supplies to occupied Holland. This began towards the end of 1944 with the west of the country most severely affected. The under-nutrition of the population was most marked between February and May 1945 when average daily food intake fell to 1,000 calories per day and eventually to as low as 500. Of the 3.3 million population of the western Netherlands at least 20,000 died as a direct result of hunger and 200,000 suffered adverse health consequences and the birth rate fell to half pre-famine levels.⁴                                             

Researchers have followed the offspring of Dutch mothers pregnant during the famine with particular emphasis on neurodevelopmental conditions such as schizophrenia ⁴. In the case of schizophrenia three criteria were used to define the exposed birth cohort in the six largest Western cities of the Netherlands. The first criterion was low food intake during the first month of gestation and those born between August and December 1945 in the cities of the famine regions met this criterion. The second criterion was conception at the height of the famine as indicated by adverse health effects in the general population. Those born later among the birth cohorts of August- December 1945 (born between October 15 and December 31) met this criterion but those born earlier (between August 1 and October 14) did not. These persons were traced through the Dutch national psychiatric registry, followed through to ages 24-48 to determine whether they had been admitted to hospital with a diagnosis of schizophrenia between 1970 and 1992. Control cohorts from periods immediately after and prior to the famine period were also investigated. The risk of schizophrenia was found to be substantially raised in the exposed cohort as compared with the controls with a relative risk of 2.0 for males and 2.2 for females. The schizophrenia cohort also had increased perinatal mortality and increased birth complications both of which are known to be associated with schizophrenia.⁵

In explanation Hoek et al have hypothesised that prenatal micronutrient deficiencies may cause neurodevelomental schizophrenia.⁴ A criticism of the study is that the numbers involved, 27, was very small. A follow up study of five males and four females with schizophrenia born between October and December, these being the only traceable subjects of the original 27, was undertaken.⁶ Their diagnosis of schizophrenia was confirmed by standard diagnostic instruments and they participated in a magnetic resonance imaging (MRI) study. They were compared with the same number and similarly sexed healthy subjects who had also been exposed to the famine conditions. Two further groups were recruited, nine schizophrenic persons and nine non-schizophrenic individuals, both groups without famine exposure. The exposed schizophrenia group was found by comparison to the others to have decreased intracranial volume. This was interpreted to have indicated stunted early brain development. However several methodological criticisms may be made. Most obviously the numbers involved were very small and the method of recruitment of the controls far from perfect.    

The Great Leap Forward Chinese famine of 1959-61 was the consequence of collectivisation of agriculture, flawed agricultural practices and reduction of cultivated land. The famine was widespread but varied from province to province. Reports of an investigation of the effects of this famine on schizophrenia derive from an isolated province of China in the Wuhu region of Anhui. The area of Wuhu and six surrounding counties were served by a single psychiatric hospital. Hospital records from 1971 to 2001 were examined. The authors found that the risk of developing schizophrenia doubled from 1958 and 1959 and concluded that prenatal exposure to famine increased the risk of schizophrenia later in life.⁷ The findings from this area, much larger than that of the Netherlands, found for the most exposed cohort an effect size similar to the Dutch. The mortality adjusted relative risk for schizophrenia over the two year period was 2.3 for 1960 and 1.9 for 1961. However the study did not have month of birth for cases or controls nor was information for food intake available month by month.

Accordingly a second more rigorous study was undertaken.⁸ This was centred on Liuzhou City and surrounding counties in Guangxi region with a population of 45 million. One hospital served the area under investigation, and had good psychiatric records covering the years 1971- 2001. The famine here was less severe than in Anhui but of considerable dimensions nonetheless. As a result there was evidence of 500,000 – 800,000 deaths and fertility reductions of the same order as in Holland. All inpatient and outpatient records of the hospital were examined using ICD 10 criteria. A twofold increased risk for schizophrenia among those conceived or in early gestation at the height of the famine was found. However this result was exclusively for rural areas.  The authors speculated on the possible deviant nutritional mechanisms involved such as the micronutrients involved in the folate pathway which may directly affect growth of the developing brain or indirectly by affecting DNA stability and regulation of genes.

Thus there is evidence that famine conditions may, as one of their consequences, increase the incidence of schizophrenia. Maternal dietary deprivation or insufficiency may translate into foetal undernourishment with adverse effects on neurological and brain development during pregnancy.

The Great Irish Famines

In Europe the Irish famines of the 1840s are notorious for their severity and adverse health consequences resulting in an estimated one million deaths and massive emigration. There is an extensive literature on the causes, characteristics and consequences of these famines such as by O’Grada.⁹ These famines were the consequence of successive and repeated failures of the potato crop on which much of the population, that had greatly increased during the previous half century, had come to depend as its main source of nutrition.¹⁰  The crop failure was the result of infestation of the potato by phyophtera infestans causing blight for which there was no known antidote at the time. Although there had been periodic potato crop failures and deficiencies in Ireland from at least the late eighteenth century, these were not due to blight, were of lesser intensity and more restricted in geographic range.¹⁰ The blights of 1845-50 were on a very different scale. The resultant series of famines are collectively known as The Great Famine.

Food and nutrition in Ireland from 1500 to the early 20^th century have been extensively investigated by Clarkson and Crawford.¹¹ They quote Arthur Young in stating that by the late 18^th century the average person consumed 6 pounds of potatoes per day and record that by 1845 close to 40% of the population lived chiefly on potatoes.¹² This occurred in a setting of population increase since 1700 and an exporting of meat, butter and grain. These authors estimate that between 1846 and 1851 over a million or 12% of the immediate pre-famine population died. “More than one third of Ireland’s population were potato people, competing for scarce plots on marginal soils and hard pressed for rent by farmers who were themselves under pressure from falling grain prices and impoverished landlords.” ¹³

The question as to the specificity of the great famine in time is a relevant issue having regard to the time limits of the famine in China and the more securely identified window of time of the Dutch occurrence. The late Professor George O’Brien doubted the uniqueness of the 1845 -1850 situation when he said that the country was in a constant state of sub-famine and that the years identified by historians as “great” were but an exacerbation of a long-standing situation.¹⁴ However scholars such as Connell ¹⁰  and O’Grada ⁹ take a different view and Clarkson and Crawford argue that “ Ireland was not chronically a famine-stricken society and that in normal years it was well stocked with nutritious food”.¹⁵

It is therefore reasonable to accept that the years 1845 – 1851 were years of devastation and mortality in which a pre-famine population of 8.5 million was greatly reduced by mortality and by emigration.  The physical effects of starvation and the accompanying exposure to the fevers and vitamin deficiencies were well documented by Wildeand others.¹⁶ Apart from the confusional states of persons dying from famine-associated fevers there is little information of the longer-run consequences for mental health. O’Grada, for example, asserted “there was little likelihood of long-lasting cohort effects in post famine Ireland” on the physical and intellectual performance of children who were born at the time.¹⁷                                       

Accordingly on the assumption that what appears to be true for Holland and China might also apply in famine Ireland the current exercise has been undertaken. It operates from a basis of many deficiencies. Statistical data relating to the question are sparse and open to a myriad of interpretations; the famine was more prolonged and less incisive in time than in the other locations examined and the ability to diagnose schizophrenia hampered by rudimentary descriptions of cases, exclusively inpatients.

Method                                                                                                                                      

The task for this study is to identify whether it is possible to adduce evidence to sustain the maternal hunger/schizophrenia hypothesis in the context of one of Europe’s severest famines of modern times. To explore this issue it is necessary to examine whether relevant health care data substantiate an increase in the disorder some 15-30 years following the major famines.  The relevant period is, therefore, between 1860 and 1875.

The available data relevant to this enquiry include numbers of admissions to lunatic asylums in Ireland over the relevant time period. In addition the issue of whether the massive emigrations from Ireland to North America and the United Kingdom in the late 1840s and early 1850s would have included migrant under-nourished pregnant women resulting in an excess of schizophrenic persons in these emigrant populations in the 1860s and 1870s is briefly considered.

Lunacy in 19^th century Ireland

The 19^th century was a period of rapid growth of the recognition and institutional provision for the mentally ill or lunatic and the intellectually disabled (idiots and imbeciles). It has been reviewed in detail by Finanne¹⁸and details of the temporal establishment of district asylums from 1830 – 1845 have been presented by Walsh.¹⁹  The main provision was in district lunatic asylums but also in the lunatic wards of workhouses established in around 1840 where residents were predominantly of idiot or imbecile type. As the years progressed a policy of transferring lunatics from workhouse to asylums was embarked upon. The following table documents the growth in the asylum population from 1824 when there was one district asylum in Armagh (although there were asylums in Dublin and Cork at this time they had not been absorbed into the district asylum system until later) to 1875 when there were 22. In addition there were smaller numbers of lunatics in goals and in workhouses.                                                

Click here for Table 1.   Years of opening of District Lunatic Asylums with numbers of patients on opening and in 1875.   

There was therefore an increase of 3,270 or 73% inpatients resident between the opening of the asylums and the numbers hospitalised in 1875.  

The reasons for the increase in these asylum populations were much debated. Broadly speaking there were two schools of commentators, those who believed that the increase reflected a genuine increase in the incidence and prevalence of lunacy such that the Times of London was moved to assert in an editorial in 1877 that “If lunacy continues to increase as at present the insane will be in the majority and, freeing themselves, will put the sane in asylums” as quoted by Scull ²² and those who believed that the increase was apparent rather than real.

In the former camp were those who believed that before 1800 schizophrenia, the most serious form of lunacy, was rare prior to the 19^th century before increasing afterwards because of genetic mutation  as did Hare ²³ whereas  Jablensky assigned the increase, on the basis of German evidence, to the 20^th century.²⁴  Another commentator concluded that schizophrenia became more prevalent during the 19^th and early 20^th century due to socio-environmental changes associated with industrial growth and biological mediating mechanisms such as nutritional, immunological and infectious causes.¹ The opposing point of view was promoted by Scull ²⁵  who, in rejecting the real increase hypothesis, invoked social conditions, such as pauperism, as contributing to the increasing influx of persons to the 19^th century asylums. However he conceded that the most satisfactory  means of deciding between the rival hypotheses was to sample the characteristics of 19^th century admission records but conceded that “there must be serious doubt the quality of surviving records is adequate for this purpose” and that “individual case records  are generally too skimpy to be useful for answering this question”^{. 25}   

In these debates in Ireland the Inspectors of Lunatics figured largely as did prominent asylum doctors of the time such as MacCabe ²⁶ and Drapes ²⁷ both of whom held the increase was real. Indeed the matter was of sufficient interest that the Inspectors devoted a Special Report to the Chief Secretary in 1884, on the “alleged increased prevalence of insanity in Ireland. ²⁸ They concluded that “the great increase in the insane under care is mainly due to ACCUMULATION (sic) and is, so far, an apparent and not a real increase”. This in fact was a compilation of the views of mental superintendents whom the Inspectors had canvassed.  Finnane, too, supported an apparent increase as explanation and cited social and administrative considerations as catalysts.²⁹ 

Administrative and legal considerations may have been just as important as any perceived increase in lunacy as a disease in contributing to the increase in asylum admissions throughout the 19^th century. In Ireland the Dangerous Lunatics Act of 1838 made it relatively easy for individuals who had committed what today are called “minor public order offences”, and sometimes even those whose level of misbehaviour was beneath this threshold, to be consigned to asylums, or to gaols before transfer to asylums. It was generally believed that this mechanism was abused with the result that many persons whose dangerousness and lunacy were questionable ended up in the asylums. An attempt to control the conveyance of persons to asylums in this manner resulted in the Dangerous Lunatics Act of 1867 which did not differ substantially from its processor other than requiring a medical certificate from the dispensary doctor and in allowing magistrates to commit “dangerous lunatics and idiotic” to lunatic asylums rather than to jails by legislation, the effect of which in the case of the Richmond Asylum, was to increase admissions to 401 in 1868 compared to 247 in 186.³⁰  In effect the new legislation, far from remedying the situation, resulted in an increase in direct admissions to asylums throughout the century. This issue is examined in depth by Finnane who attributed it in part to “the widening of insanity’s boundaries” ³¹ thus raising further nosocomial caution on the interpretation of the reasons for admission increases following the famine.  And for Finnane the familial context, particularly in its socio-economic context, was at least as important in determining admission sought by relatives as the diagnostics labels appended by asylum doctors; ”it is the history of familial relations which is essential to appreciating the decision to commit”.³²  As an example of commitment because of economic necessity, Malcolm, in her history of Swift’s Hospital  illustrates the dilemma encountered by a certain Mary Larkin in deciding her to apply for the re-admission of her husband Thomas.^33. 

Incidence 1860-1875

There is no reliable information available on new cases of lunacy arising in the Irish community in the 19^th century. However periodic census counts of “lunatics at large” were carried out by the Royal Irish Constabulary at the request of the Inspectors of Lunacy in the 200 constabulary areas of Ireland on a regular basis.  It might have been possible to assess an increasing incidence of such cases by comparing one year with another and interpreting an increase as indicating new cases on an annual basis. However the arbitrariness of the Constabulary’s identification of lunacy, which included intellectual disability, excludes the usefulness of this information source. Accordingly it is necessary to rely on asylum admission data as a measure of the incidence of schizophrenia as returned in the Annual Reports on the District, Criminal and Private Lunatic Asylums in Ireland as provided by the Inspectors of Lunacy, the greatest proportion of which were to the district asylums.   

Given that the incidence of schizophrenia is mostly concentrated in the population aged between 15 and 30 years, it is assumed that the impact of the Irish famines of 1845- 51 would be manifest mainly in an increase in hospital admissions for lunacy, and  more specifically for conditions analogous to schizophrenia, in Ireland between 1860 and 1875. Admissions to the district asylums, over 80% of which were recorded as first admissions, rose from 1,313 in 1860 to 2,132 in 1875 and then increased only slightly to 1880 when they numbered 2,366.

Click here for Table 2.  Numbers of admissions to District Lunatic Asylums 1860-1875

There was, thus, an increase of 62% in the number of admissions between 1860 and 1875.  As the population fell over these years the rate per 100,000 population rose more rapidly than the raw numbers, from 22.6 to 40.4 or by 78.7%.  However, there was no decline in admissions in the years after 1880, when any famine effect would be expected to have petered out. On the contrary, admissions increased by a further 32% to 3,095 in 1890 and by 1898 had reached 3,469. First admissions constituted in and around 80% from 1861 onwards. Admissions to private hospitals increased from 165 in 1860 to 186 in 1875 and constituted 2,882 (9%) of 32,009 total private and public admissions over 1860-75. No diagnostic information was furnished on these private admissions, although it was provided on those resident each year with mania predominating. Because the numbers are small and there was little increase over the period surveyed they are discounted form further consideration. Similarly the 290 admissions to the Central Criminal asylum over these years have been discounted.

Diagnosis in the nineteenth century

Whereas in the 20^th century medical practitioners were familiar with the concept of schizophrenia, introduced in the early 1900s, this was not the case in the preceding century.  The term lunacy was often employed generically and administratively to include both those suffering from mental illness and those with intellectual disability (idiots and imbeciles). However although this generic usage is sometimes employed in official reports, such as the annual inspection reports employed here, these usually use lunacy in the more restricted sense of mental illness per se. Within lunacy a very restricted classificatory system was used. The most common diagnostic terms were mania, melancholia, monomania and dementia. I have examined  Irish asylum casebooks of the Sligo, Mullingar and Richmond asylums from the 1850s to 1900 and attempted, from the limited clinical descriptions available, to reconcile these terms with diagnostic groupings currently in use in the International Classification of Diseases 10^th edition (ICD 10). While in a minority of cases the symptoms and historical data recorded are specific enough to warrant a diagnosis in modern terms of depression with some confidence, this is not so in relation to the broader concept of schizophrenia, an entity unknown as such at that time.  For example, delusional thinking and hallucinatory experiences, characteristic of this disorder, were rarely noted in the Irish nineteenth century case books quoted.

The following cases from the Sligo Asylum casebooks, typical of the generality of admissions, illustrate the practical difficulties encountered in diagnostics of the time.³⁵ A 45 year old woman was admitted under warrant to the asylum which stated that she threatened and assaulted her mother with whom she did not get on. Nevertheless she was given a diagnosis of chronic mania and the supposed cause of her insanity was identified as “family disturbances”. Confusingly the “duration of present attack” was given as 15 years. The sparse case notes indicate only that she had “from time to time maniacal symptoms”. She was still undischarged seven years later. A 33 year old female was admitted because she was alleged to have assaulted her sister and threatened to burn her father’s house. The duration of her illness prior to admission was said to be one month. Sixteen years following admission she was said to be “noisy and refractory” and she died in the asylum 41 years following admission. A 35 year old male was admitted because he threatened to kill wife and family and was stated to have been ill for only three weeks prior to admission. He was noted in his case notes to be suffering from delusional insanity with jealous delusions concerning his wife but was noted to have taken a lot of drink prior to admission. Three weeks after admission he “escaped”, couldn’t be found and so was discharged from the asylum register a fortnight later.

This contrasts markedly with the situation pertaining in late nineteenth century Denbigh Asylum in North West Wales where case notes were “more comprehensive than in other asylums of the period” and were sufficiently detailed to permit consultant psychiatrists to make an ICD diagnosis on each patient.³⁶ A similar exercise was possible at the Retreat in York, dealing with patients admitted 1880-1884 where diagnostic information was sufficiently explicit to allow of ICD conversions.³⁷  More pertinent to the Irish dilemma is the finding of researchers seeking to extract schizophrenia from admissions to the Bethlem Royal Hospital 1853-1862. Having reviewed the diagnostic criteria set out in contemporary psychiatric textbooks they concluded that mania comprised insanity with “confusion of ideas” and “encompassed all syndromes where thought disorder was evident”.³⁸ Moreover, in identifying schizophrenia they excluded all persons aged over 40. This is not possible in Ireland because of lack of cross-classification by disease category and age in the Irish reports.

I now turn to estimating how many of Irish asylum admissions should be classified as schizophrenia. There has been surprisingly little attempt to determine what proportion of 19^th century lunacy emerges as schizophrenia as it is understood today. An outstanding exception to this general scenario is that of Hare. ²³ In examining the difficult issues involved Hare warned that “Before modern diagnostic criteria became generally accepted, there was much difference of opinion on what signs and outcomes were indicative of a schizophrenic illness. And what was a difficult decision in clinical practice was more likely to be contentious in a historical setting even when a detailed history was available.  Kraepelin, to whom we owe the concept that was later to emerge as schizophrenia, and which he had called dementia praecox, stated that many of the cases he identified as dementia praecox had previously been classed as mania or melancholia.³⁹ Hare, speaking of the 19^th century, states that “we may assume that almost all cases classified as “ordinary dementia” would have been schizophrenia”.²³ Further support for this is supplied by Tuke who subdivided ordinary dementia into two forms. Primary dementia was the form that occurs most especially in young persons of feeble development and secondary was the form that “follows acute attacks of insanity, maniacal or melancholic”.⁴⁰ Of course the clinical manifestations of schizophrenia may have changed over the past 100 years, and while this is more likely to be true of earlier periods, it is still a factor requiring consideration, in translating 19^th century case book descriptions, even when exhaustive as they seldom were, in Irish 19^th century case books, to the modern concept of schizophrenia.

Mania was the predominant diagnosis of mental illness in nineteenth century Ireland, comprising 72% of admissions 1860-75.  This clearly suggests, as pointed out above, that as well as including mania as it is known today, other categories must have been subsumed into this entity, most notably schizophrenia. This assumption gains support from the contemporary evidence, that of schizophrenia and mania first admissions combined, schizophrenia now comprises 60%.  I have assumed that the relative distribution of these conditions was similar in the nineteenth century and have re-classified 60% of nineteenth century admissions, classified then as mania, to what we call schizophrenia today. I further assume that the nineteenth century category monomania connotes delusional disorder and belongs in its entirety to the schizophrenia spectrum. The term dementia was employed non-specifically in the nineteenth century admissions classification and seems often to have included those with the negative symptoms of schizophrenia, as well as dementia in the modern sense of cognitive failure of organic origin, particularly in older persons. Support for this contention is provided by the observation by Hare that the age –incidence curve or age at first admission for dementia in the 19^th century was largely in the younger age groups and therefore not compatible with the modern concept of this condition and he therefore aligned much of it with schizophrenia.²³ However this cannot be tested in the Irish context as no data are available for diagnosis cross- classified by age. I have therefore, somewhat arbitrarily, allocated 50% of dementia admissions to schizophrenia.  As melancholia closely resembles depression as used today, this category has been regarded as not contributing to schizophrenia on the assumption that depressive syndromes were the predominant characteristic of those labelled melancholia. However as noted by Tuke ⁴⁰ some cases of melancholia, passing into a chronic state, might conceivably be re-labelled dementia.

There were 1,313 admissions to district asylums in 1860, a year when one would have expected famine–related admissions to begin to appear. Excluding the 220 “relapsed” cases there were 1,093 first admissions, 83% of the total.  Four categories of mental illness accounted for 96% of all admissions (the remainder comprised idiots and imbeciles).  The breakdown of these four categories was: mania 892 (68%), dementia 88 (7%), monomania 53 (4%) and melancholia 220 (17%). Here one encounters the problem of assessing or best-guessing what proportion of these could be validly regarded as schizophrenic. The assumption, based on the very tenuous evidence of contemporary case- books with their admittedly poor symptomatic descriptions, is made that the following proportions of these categories were what to-day is called schizophrenia, mania 60%, monomania 100%, dementia 50%, and melancholia 0%.  This yields an estimated total of 632 admissions for schizophrenia in 1860 (50% of all mental illness admissions) or 524 first admissions on the basis that 83% were first admissions.  In 1875 there were 2,344 admissions of which 1,777 (83%) were first admissions. The equivalent estimate for 1875 was 1,006 schizophrenia admissions of which an estimated 834 were first admissions.  The estimation therefore is that the first admission rate for schizophrenia rose from 8.4 per 100,000 in 1860 to 15.6 in 1875.  However, as the admission rate for non-schizophrenia conditions increased to the same extent, the proportion of all admissions classified as schizophrenia remained stable. The following figures represent these data.

Click here for Fig. 1. Schizophrenia admission rates per 100,000 population 1860-1875 from 9^th to 25^th Reports on the Public Criminal and Private Asylums of Ireland ⁴¹.

Click here for Fig. 2. Schizophrenia as a percentage of all admissions 1860 – 1875.  

Given that schizophrenia is predominantly a disorder of early life with most incident cases arising in the late teens and early 20s I have attempted to determine whether there was any increase in the proportion of young persons admitted during the relevant years as a proportion of all-aged admissions. The Inspectorial reports supply age of admissions in decennial groups and not cross classified by diagnosis. The group most relevant to this enquiry is that of 20 – 30 years. The earliest years for which admission ages were provided were in the combined years 1856 and 1857. In these years 427 or 27.8% of 1,532 admissions were in this age group. This percentage rose to 34.1 in 1868 and then subsided to 28.7 in 1875 thereby giving no support to the question of whether schizophrenia increased insofar as it could be identified by age on admission.⁴²

The Irish Abroad     

Robins contends that “the Irish who left home during the famine and post-famine decades were more susceptible to insanity than immigrants of other racial origins”.⁴³ However he cites no quantative evidence in support of this general contention although he quotes instances where persons who had become mentally ill following emigration were returned by their families or, as in the case of the North American states, were returned by administrative decree. Nonetheless there is abundant evidence of the high prevalence of mental illness among the immigrant Irish compared to indigenous populations both in the US and UK in the mid and late 19th century. For example lunacy in Massachusetts was noted to be high among the immigrant Irish.⁴⁴  However this was in 1855 less than a decade after the major famines of the 1840s and therefore too early to be related to them. Other reports of the high proportion of Irish in asylum populations came from the Canadian provinces, New Brunswick, before the famine years and Prince Edward Island, subsequent to them, where in 1864 it was claimed that as many as one third of admissions were of Irish immigrants reflecting perhaps more than anything else the very high proportion of the population that was Irish.⁴⁵    Nonetheless high rates of hospital admissions among the Irish of New York City and State were still extant up to 1900.⁴⁶  These were too long after the major famines to be attributed to them. Moreover these rates rose progressively throughout the latter part of the nineteenth century and showed no exceptional peak between 1865 and 1875. The rates of hospitalisation of Irish emigrants in North American asylums declined over time, in keeping with the observation that as each immigrant group becomes more assimilated and more prosperous the rate of public psychiatric hospitalisation decreases. Overall, though, these sparse and general observations shed little light on the question at issue.

Irrespective of nutritional status, the trauma of migration and the socio-cultural difficulties of assimilation may of themselves be sufficient to increase mental disorder in migrant populations. Classical examples of this have been identified by Odegaard among Norwegian immigrants to Minnesota ⁴⁷ and by Harrison among Afro-Caribbean migrants to the United Kingdom. ⁴⁸ And the migrant Irish in the United Kingdom, even to the first generation UK born, appear to have poorer mental health than the indigenous London community.⁴⁹ Therefore caution must be invoked in attributing mental illness rates to 19^th century Irish immigrants solely to maternal nutritional deficiency.                                                                  

Discussion                                                                                                                          

The plausibility of famine disrupting neurodevelopment has a sound empirical basis. Famine conditions have been shown to result in decreased fertility, increase in miscarriage, stillbirths and low birth weight. ⁴  Because schizophrenia is believed, in part, to reflect developmental anomalies in brain structure it is relevant to postulate that famine conditions, existing during pregnancy, may result in neurodevelopmental damage to the foetus. Accordingly the natural experiments of famine conditions in two jurisdictions have been examined to determine whether there was an increase in schizophrenia in individuals exposed to famine conditions during pregnancy. These wee respectively in Holland during World War 2 ⁴ and in China during the Great Leap Forward famine.⁸ Because of the severity of the Great Irish Famine and its resulting mortality it is reasonable to suspect that the accompanying undernutririon of pregnant women may have similarly resulted in neurological damage leading to an increase in schizophrenia some 15 to 30 years later.                            

The reason for the growth in the numbers of persons in Irish asylums during the 19^th century led to vigorous debate. Essentially there were two points of view, those that held that it reflected a real increase in lunacy and those who claimed that it was artefactual and apparent rather than real. Explanatory reasons deriving from ecological and environmental causes or influences proliferated. However this increase was not uniquely Irish but a feature of most European and North American jurisdictions²³

The data presented here show an increase in the incidence of lunacy in Ireland as measured by asylum admissions some 15 to 30 years following the Irish famines of 1845-1850 historically referred to as The Great Famine. Admissions of lunatics, that is those suffering from mental illness, to asylums increased 1860-1875 from 1,313 to 2,132 or in rates per 100,000 population from 22.6 to 40.4, an increase of 78.7%. By assigning 60% of patients diagnosed as mania, all those designated monomania and 50% of those designated dementia to schizophrenia, estimates have been made of the numbers likely to have been schizophrenia in those first admitted in 1860 and 1875.   Those first admissions identified as schizophrenia rose numerically from 524 to 834 and in rates per 100,000 population from 8.4 to 15.6 an increase of 85.7%. 

At first sight these increases in Ireland would seem to suggest that the Irish famines did lead to an increased level of schizophrenia in the population, but account has to be taken of the similar increases in the other “non-schizophrenia” lunacies, mainly melancholia whose first admissions rose from 31.7 to 45.5 per 100,000 from 1860-75 an increase of 43.5 ⁴¹.

In addition admission rates continued to increase up to the end of the century long after the Great Famine could be held to be an influence. As to the migrating Irish, other factors confound the situation such as poverty and difficulties in assimilation of the immigrant population, which are deemed to contribute to the high hospitalisation rates in many immigrant communities.⁴⁷

Up to 1881 the rate of first admission to population was higher in England than it was in Ireland.⁵⁰ The prevalence of persons in asylums and workhouses in England rose from 70 per 100,000 population in 1847 to 220 in 1877. ^{51, 52} In Ireland the corresponding figures were 76 and 234. It can therefore be reasonably concluded that the rates of insanity (lunacy plus a small number of idiots and imbeciles) were remarkably similar in both jurisdictions and further that they increased at roughly the same rate in the second half of the nineteenth century. In consequence the record offers little support for the thesis that the increase in rates was attributable to the famines of 1845-51.

As far as Ireland is concerned the evidence that the famines of the late 1840s led to more schizophrenia is, at best, equivocal. The apparent increase in the number of those schizophrenic was in the context of an increase in lunacy generally and the increase observed in Ireland was manifest throughout Europe and North America in jurisdictions where there were no major famines.⁴⁵                                                                            

It is concluded that no unequivocal evidence can be adduced to support the hypothesis that the Great Irish famine increased schizophrenia.

Limitations        

It may be objected that 1860 is too early a date for the consequences of the famines to be revealed in asylum admissions.  Furthermore, the timing of the admissions may not have coincided exactly with the onset of the condition. Whereas the Inspectorial Reports of the 1860s tabulate the duration of disease prior to admission of those discharged as “recovered”, this information is not provided for new admissions nor is it cross-classified by type of disease. In addition, form of disease on admission was not provided in the reports after 1875 until 1890 and by then monomania no longer appeared as an entity. This is noteworthy as it might be objected that delusional disorder has a later onset than other components of the schizophrenia spectrum.

A shortage of asylum beds could have caused delays in admissions in the 1860s and increased availability of beds – rather than increased incidence of mental illness – could have accounted for some of the rise in admissions in later years.  By 1875, although the number of asylum places available had increased considerably, by almost 3,000 from 1860, admissions fell slightly between 1870 and 1875, as did the number of lunatics reported as at large .^34.                                          

The use of a single year at either end of exploration may be questioned but there was little variation in the characteristics of the admission or residential clienteles over the years of survey.  

Finally, it is acknowledged that the sparseness of clinical data in nineteenth century asylum case books in Ireland does not allow translation of what little clinically descriptive material there is into meaningful diagnostic entities as applied today, a difficulty not confined to Ireland.²³ The most restricting limitation, therefore, is the derivation of rates of schizophrenia based on purely personal and empirical extrapolation from 19^th century diagnostics.  

Acknowledgement.

I wish to thank Dr Brian Donnelly of the Irish National Archive for his help and advice and particularly for making the casebooks of the Sligo District Lunatic Asylum available to me.

Conflict of interest

None.

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