• About Epidemiology Research at QCMHR

• Epidemiology Projects

• Epidemiology Publications

Staff

• Professor John Mcgrath Click Here For Biography
• Dr. David Chant (Principal Research Fellow)
• Joy Welham
• Sukanta Saha
• Jennie Robertson

PhD Students

• James Scott
• John Allan

Funding

The Epidemiology Group is funded by Queensland Health Department and Stanley International Research Centre.

Aims

To apply epidemiological techniques to generate and test potential risk factors for schizophrenia and related psychoses, with a particular emphasis on the identification of non-genetic, early life exposures.

Basic principles informing our research

• Non-genetic factors substantially influence the cause and course of schizophrenia.
• The incidence of schizophrenia varies across time (within year and between years) and across place (between nation studies, migrant studies).
• We need to identify these temporal and spatial gradients in order to generate candidate exposures.
• Many of these putative exposures occur in a critical window from conception to the first few years of life.
• The identification of genetic and nongenetic risk-modifying factors will provide the best leads to unraveling the pathogenesis of psychosis (i.e. “bottom-up approach”).
• The "epidemiological map" of schizophrenia based on Australian/Queensland data may provide informative contrasts to data derived from Northern Hemisphere countries.
• Research has largely excluded the existence of large-effect single genes related to schizophrenia. Now the search has focused on multiple genes each of small effect. It is probably that a similar scenario exists for nongenetic factors for schizophrenia.
• We need to develop research strategies that can identify exposures that are weak (relative risk of 1.5-2.0) but prevalent (40-70%). These combinations could account for up to 20% to 40% of all cases.
• Weak and prevalent exposures will be difficult to detect (e.g. they may seem too obvious or innocuous to be candidates) and difficult to prove (e.g. large sample sizes required, the inherent limitations of epidemiological research with respect to proving causality).
• Candidate exposures may be found in the domains of prenatal infection, prenatal nutrition, and other pregnancy and birth complications. These are our "hot spots".
• A clearer understanding of the nongenetic risk factors of schizophrenia will provide the best leads for the primary prevention of schizophrenia.
• Exposures that provide opportunities for cheap and safe universal public health interventions should be given the highest priority, given the important potential "pay-off" (e.g. nutritional supplements, vaccinations etc).
• The application of modern neuroscience techniques (e.g. animal models, gene arrays) may help rank order and/or eliminate candidate exposures (see Developmental Neurobiology Group and our Genetics Group).
• In light of the substantial “unavertable” disability associated with schizophrenia, we need to maintain a sense of urgency about our task.

Current Projects

Incidence and Prevalence of Schizophrenia

Understanding variations in the incidence and prevalence of schizophrenia is a crucial step in unravelling the aetiology of this group of disorders. Since 2002 much of our research has focused on reviews to systematically identify studies related to the incidence and prevalence of schizophrenia, to describe the key features of these studies, and to explore the distribution of rates derived from these studies. Reviews of incidence studies have been completed, and reviews of prevalence studies are near complete.

Click here to view the Incidence and Prevelance of Schizophrenia website

Incidence studies

Studies with original data related to the incidence of schizophrenia and which were first published between 1965 and 2001 were identified via searching electronic databases, reviewing citations and writing to authors. These studies were divided into core studies, migrant studies, cohort studies and studies based on Other Special Groups. Between- and within-study filters were applied in order to identify discrete rates. The distribution of discrete rates was described with quantiles and moments of the distribution and these distributions were compared when the underlying rates were sorted according to sex, urbanicity, migrant status and various methodological features.

We identified 100 core studies, 24 migrant studies, 23 cohort studies and 14 studies based on Other Special Groups. These studies, which were drawn from 33 countries, generated a total of 1,458 rates. Based on discrete core data for persons (55 studies and 170 rates), the distribution of rates was asymmetric and had a median value (10% and 90% quantile) of 15.2 (7.7, 43.0) per 100,000. The distribution of rates was significantly higher in males compared to females (male/female rate ratio median (10% and 90% quantile) = 1.40 (0.86, 2.37)). Those studies conducted in urban versus mixed urban-rural catchment areas generated significantly higher rate distributions. The distribution of rates in migrants was significantly higher compared to native born; the migrant/native born rate ratio median (10% and 90% quantile) was 4.61 (0.98, 12.75)). Apart from the finding that older studies tended to report higher rates, overall quality and methods related to case finding diagnostic confirmation and criteria, the use of age-standardization and age range did not significantly differentiate the rate distributions.

There is a wealth of data available on the incidence of schizophrenia. The width and shape of the overall distribution of rates, and the significant impact of sex, urbanicity and migrant status on these distributions, demonstrate the rich and informative qualities of these data.

Prevalence studies

• This project systematically reviews studies related to prevalence of schizophrenia to explore the distribution of rates. To date over 1000 potential papers have been identified. These are currently being reviewed and will be followed by data analysis.

Other recent studies

• Birth order and between sibling birth interval . This project uses the BPS pedigree data to explore these variables. Finding: No association between birth order and psychosis
• Co-segregation of diseases with families of patients with psychosis . This project examines the prevalence of a range of psychiatric and physical disorders (eg. autoimmune, neuropsychiatric, endocrine) in families in the BPS.
• Birth anthropometry and sunshine . This project uses the Mater University Study of Pregnancy (MUSP) data to explore the association between anthropometric measures at birth and duration of sunshine.

• Animal experiments and in vitro experiments (links with Developmental Neurobiology group)

Past projects

• Season of birth (MHSS*)
• Meta-analysis of southern Hemisphere Season of Birth studies (MHSS and other registers)
• Prenatal influenza epidemics (MHSS)
• Age of onset lags (MHSS)
• Fertility and fecundity of psychosis (Community clinic survey)
• Seasonality of first admissions (MHSS)
• Mixture models and age of onset (MHSS)
• National Survey of Mental Health and Wellbeing - low prevalence disorders (Jablensky and others)
• Brisbane Psychosis Study (BPS)

• Systematic review and meta-analysis of season of birth studies from the northern hemisphere. Findings: Season of Birth effect varies in timing and size between sizes. Weak latitude effect.
• The development of statistical methods to identify fluctuations/variability in schizophrenia birthrate time series. The development of robust methods to identify agreement between time candidate exposures or their proxy (eg. sunshine duration) and schizophrenia birth rates.

• Prenatal poliomyelitis. No associations found between polio epidemics and schizophrenia or affective psychosis.

* Queensland mental Health Statistics System

Vitamin D hypothesis

• Duration of sunshine and schizophrenia - Queensland, The Netherlands. Collaborator: Jean-Paul Selten ( Utrecht University, The Netherlands). Findings: association between falling sunshine duration and rising schizophrenia birth rates for males only. Association between reduced duration of perinatal sunshine and age of first registration.
• Factors that influence vitamin D levels in the general population. Based on BPS data. Collaborators: Michael Kimlin and Alfio Parisi, University of Southern Queensland. Findings: lowest vitamin D levels in winter, however large within-month variability due to behaviour. Urban-rural gradient confirmed. Association between duration of sunshine and mean vitamin D level confirmed.
• Modeling the relationship between latitude, climate and the “vitamin D” UV spectrum. Collaborators: Kimlin and Parisi, University of Southern Queensland. Findings: Computer simulations now available to map UV across time and space.

Age of first registration

• Queensland and Brazil. Collaborator: Sergio Andreoli (Federal University of Sao Paulo, Brazil). Findings: similar curves in the two nations, but Queensland has an excess of males.
• Mixture models to identify subgroups and the influence of risk factors. Collaborator: Geoff McLachlan ( University of Queensland). Ongoing.
• Affective psychosis: Comparing ICD8/9 296 with and without adjustments to schizophrenia. Findings: when 296.1 removed, the onset curve is similar to that for schizophrenia.

Other Projects:

• Descriptive statistics of the endorsement of CIDI psychosis screening items (n = 10,000). Collaborators: Gavin Andrews (Uni of New South Wales). Findings: Age but no sex gradients in endorsement profile. Brisbane Psychosis Study
• he range of beliefs and experiences in the community. Quasi delusions, hallucinations, and thought disorder in well controls. Findings: Age but no sex gradient in profile. Family history associated with scores. Different domains are positively correlated.

• Urban/rural place of birth and place of residence (first five years of life) and migrant status (first and second generation migrants). Findings: No association between place of birth and risk of psychosis. First generation have reduce risk of psychosis, no difference in psychosis in the second generation.
• Minor physical anomalies and quantitative cranio-facial measures. Findings: More MPAs, wider skull base and shorter middle third of face in psychosis. Association between these variables and family history, obstetric complications and age of onset.
• Maternal and Paternal age. Collaborators: Preben Mortensen (Aarhus) and Tom McNeil ( Malmo). Findings: Significant finding for older fathers in Denmark and Sweden, but not for Brisbane. No effect for mothers (when controlled for age of fathers).  

Epidemiology Publications 1998-2004.

Journal articles

McGrath JJ, Welham JL (1999) Season of birth and schizophrenia: a systematic review and meta-analysis of data from the Southern Hemisphere. Schizophrenia Research 35 237-242

McGrath JJ, Hearle H, Jenner L, Plant K, Drummond A, Barkla JM (1999). The fertility and fecundity of patients with psychosis. Acta Psychiatrica Scandinavica 99: 441-446.

McGrath J. (1999) Hypothesis: Is low prenatal vitamin D a risk-modifying factor for schizophrenia? Schizophrenia Research 40: 173-177.

Davies G, Ahmad F, Chant D, Welham J, McGrath J. (2000) Seasonality of first admission for schizophrenia in the Southern Hemisphere. Schizophrenia Research. 41(3):457-62.

Jablensky A, McGrath J, Herrman H, Castle D, Gureje O, Carr V, Morgan V, Korten A. Harvey C (2000). Psychotic disorders in urban areas. Australian and New Zealand Journal of Psychiatry. 34: 221-236.

Welham J, McLachlan G, Davies G, McGrath J. (2000) Heterogeneity in schizophrenia: mixture modelling of age-at-first-admission, gender and diagnosis. Acta Psychiatrica Scandinavica. 101: 312-317.

Gastal FL , , Andreoli SB, Quintana MIS, Gameiro MA, Leite SO, McGrath JJ. (2000). Predicting the revolving door phenomenon among patients with schizophrenic, affective and non-organic psychoses (Fatores preditores do fenômeno de reinternações repetidas (recidivismo) de pacientes com diagnósticos de esquizofrenia, transtorno afetivo e psicose não orgânica). Journal of Public Health (Revista de Saude Publica), 34: 280-285.

Barkla J, Byrne L, Hearle J, Plant K, Jenner L, McGrath J. (2000) Pregnancy in women with psychotic disorders. Archives of Women’s Mental Health. 3: 23-26.

Welham J, Davies G, Auliciems A, McGrath J. (2000) Climate, geography and the search for candidate nongenetic risk factors for schizophrenia. International Journal of Mental Health. 29; 79-100. Invited review article.

McGrath J. (2000) Universal interventions for the primary prevention of schizophrenia. Australian and New Zealand Journal of Psychiatry. 34 (suppl) S58-S64.

McGrath J. Does “imprinting” with low prenatal vitamin D contribute to risk of various adult disorders? Medical Hypotheses. In press.

Downs , N.J. , Kimlin, M.G., Parisi, A.V. & McGrath, J.J. Modelling human facial UV exposure. Radiation Protection in Australasia. In press.

McGrath J, Croudace T, Jones P. Prevention of schizophrenia – an impossible dream? In Epidemiology of Schizophrenia Eds Murray RM, Jones PB, Susser E, van Os J, Cannon M. Cambridge University Press. In press.

McGrath J, Welham J, Davies G, Chant D, Auliciems A. (2000) Schizophrenia birth rates and the El Nino southern oscillation: preliminary analysis. P99-102. In Biometeorology and Urban Climatology at the turn of the Millenium. Eds. De Dear RJ, Kalma JD, Oke TR, Auliciems A. World Meterological Association. Geneva. McGrath J , Murray R. Risk factors for schizophrenia: from conception to birth, In Schizophrenia Eds Weinberger D, Hirsch S. Blackwell Scientific Publication. (Substantially rewritten and expanded for 2nd edition due for release in 2002).

Jablensky A, McGrath J, Herrman H, Castle D, Gureje O, Morgan V, Korten A. (1999). People living with Psychotic Illness: An Australian Study 1997-1998. Commonwealth of Australia.

Jablensky A, McGrath J, Herrman H, Castle D, Gureje O, Morgan V, Korten A. (1999). People living with Psychotic Illness: An Australian Study 1997-1998. An overview. Commonwealth of Australia.

Castle D, McGrath J, Kulkarni J. Women and Schizophrenia. Cambridge University Press. 2000

McGrath JJ, Kimlin M, Saha S, Eyles D, Parisi A. (2001) Vitamin D insufficiency in south-east Queensland. Medical Journal of Australia. 174; 150-151.

McGrath J, El-Saadi O, Cardy S, Chapple B, Chant D, Mowry B: Urban birth and migrant status as risk factors for psychosis: an Australian case-control study. Soc Psychiatry Psychiatr Epidemiol 2001; 36(11):533-6.

McGrath J: Does 'imprinting' with low prenatal vitamin D contribute to the risk of various adult disorders? Med Hypotheses 2001; 56(3):367-71.

McGrath J, Chapple B, Wright M: Working memory in schizophrenia and mania: correlation with symptoms during the acute and subacute phases. Acta Psychiatr Scand 2001; 103(3):181-8.

Soares KV, McGrath JJ: Vitamin E for neuroleptic-induced tardive dyskinesia. Cochrane Database Syst Rev 2001(4):CD000209.

Soares KV, McGrath JJ, Deeks JJ: Gamma-aminobutyric acid agonists for neuroleptic-induced tardive dyskinesia. Cochrane Database Syst Rev 2001(2):CD000203.

Soares KV, McGrath JJ: Calcium channel blockers for neuroleptic-induced tardive dyskinesia. Cochrane Database Syst Rev 2001(1):CD000206.

Welham J, Haire M, Mercer D, Stedman T: A gap approach to exploring quality of life in mental health. Qual Life Res 2001; 10(5):421-9.

Andreoli SB, Gastal FL, Leite SO, Welham J, McGrath J: Age-at-first-registration in schizophrenia: a comparison of mental health registers from Australia and Brazil. Schizophr Res 2002; 54(3):277-9.

Cahill M, Chant D, Welham J, McGrath J: No significant association between prenatal exposure poliovirus epidemics and psychosis. Aust N Z J Psychiatry 2002; 36(3):373-5.

Cameron AM, Oram J, Geffen GM, Kavanagh DJ, McGrath JJ, Geffen LB: Working memory correlates of three symptom clusters in schizophrenia. Psychiatry Res 2002; 110(1):49-61.

Copland D, Chenery H, Savage G, McGrath J: An on-line investigation of lexical ambiguity processing in schizophrenia. Brain Cogn 2002; 48(2-3):324-7.

Elizarras-Rivas J, Fragoso-Herrera R, Cerdan-Sanchez LF, Ramos-Zepeda R, Totsuka-Sutto SE, Gallegos-Arreola P, Saha S, McGrath J: Dermatoglyphics and schizophrenia: a Mexican study. Aust N Z J Psychiatry 2002; 36(5):704-5.

Eyles DW, McGrath JJ, Reynolds GP: Neuronal calcium-binding proteins and schizophrenia. Schizophr Res 2002; 57(1):27-34.

Kavanagh DJ, McGrath J, Saunders JB, Dore G, Clark D: Substance misuse in patients with schizophrenia: epidemiology and management. Drugs 2002; 62(5):743-55.

Leucht S, McGrath J, White P, Kissling W: Carbamazepine for schizophrenia and schizoaffective psychoses. Cochrane Database Syst Rev 2002(3):CD001258.

Leucht S, McGrath J, White P, Kissling W: Carbamazepine augmentation for schizophrenia: how good is the evidence? J Clin Psychiatry 2002; 63(3):218-24.

McGrath J, El-Saadi O, Grim V, Cardy S, Chapple B, Chant D, Lieberman D, Mowry B: Minor physical anomalies and quantitative measures of the head and face in patients with psychosis. Arch Gen Psychiatry 2002; 59(5):458-64.

McGrath J, Selten JP, Chant D: Long-term trends in sunshine duration and its association with schizophrenia birth rates and age at first registration--data from Australia and the Netherlands. Schizophr Res 2002; 54(3):199-212.

Perry C, Mackay-Sim A, Feron F, McGrath J: Olfactory neural cells: an untapped diagnostic and therapeutic resource. The 2000 Ogura Lecture. Laryngoscope 2002; 112(4):603-7.

Tammenmaa IA , McGrath JJ, Sailas E, Soares-Weiser K: Cholinergic medication for neuroleptic-induced tardive dyskinesia. Cochrane Database Syst Rev 2002(3):CD000207.

Cameron AM, Geffen GM, Kavanagh DJ, Wright MJ, McGrath JJ, Geffen LB: Event-related potential correlates of impaired visuospatial working memory in schizophrenia. Psychophysiology 2003; 40(5):702-15.

Davies G, Welham J, Chant D, Torrey EF, McGrath J: A systematic review and meta-analysis of Northern Hemisphere season of birth studies in schizophrenia. Schizophr Bull 2003; 29(3):587-93.

Elizarraras-Rivas J, Fragoso-Herrera R, Cerdan-Sanchez LF, Ramos-Zepeda R, Barajas-Barajas LO, Troyo-Sanroman R, McLean D, McGrath JJ: Minor physical anomalies and anthropometric measures in schizophrenia: a pilot study from Mexico. Schizophr Res 2003; 62(3):285-7.

Evans K, McGrath J, Milns R: Searching for schizophrenia in ancient Greek and Roman literature: a systematic review. Acta Psychiatr Scand 2003; 107(5):323-30.

Gureje O, Miles W, Keks N, Grainger D, Lambert T, McGrath J, Tran P, Catts S, Fraser A, Hustig H, Andersen S, Crawford AM: Olanzapine vs risperidone in the management of schizophrenia: a randomized double-blind trial in Australia and New Zealand. Schizophr Res 2003; 61(2-3):303-14.

Handoko HY, Nancarrow DJ, Hayward NK, Ohaeri JU, Aghanwa H, McGrath JJ, Levinson DF, Johns C, Walters MK, Nertney DA, Srinivasan TN, Thara R, Mowry BJ:

Leucht S, McGrath J, Kissling W: Lithium for schizophrenia. Cochrane Database Syst Rev 2003(3):CD003834.

McGrath JJ: Invited commentary: Gaining traction on the epidemiologic landscape of schizophrenia. Am J Epidemiol 2003; 158(4):301-4.

McGrath JJ, Feron FP, Burne TH, Mackay-Sim A, Eyles DW: The neurodevelopmental hypothesis of schizophrenia: a review of recent developments. Ann Med 2003; 35(2):86-93.

McGrath J, Eyles D, Mowry B, Yolken R, Buka S: Low maternal vitamin D as a risk factor for schizophrenia: a pilot study using banked sera. Schizophr Res 2003; 63(1-2):73-8.

Saha S, Loesch D, Chant D, Welham J, El-Saadi O, Fananas L, Mowry B, McGrath J: Directional and fluctuating asymmetry in finger and a-b ridge counts in psychosis: a case-control study. BMC Psychiatry 2003; 3(1):3.

Welham JL, Thomis R, McGrath JJ: Age-at-first-registration and heterogeneity in affective psychoses. Aust N Z J Psychiatry 2003; 37(1):66-9.

McGrath J, Saha S, Welham J, El Saadi O, MacCauley C, Chant D: A systematic review of the incidence of schizophrenia: the distribution of rates and the influence of sex, urbanicity, migrant status and methodology. BMC Psychiatry 2004; under review

McLean D, Feron F, Mackay-Sim A, McCurdy R, Hirning M, Chant D, McGrath J: Paradoxical association between smoking and olfactory identification in psychosis versus controls. Aust N Z J Psychiatry 2004; 38(1-2):81-.