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Age-at-onset and schizophrenia: reversed gender effect
B N Gangadhar1, C Panner Selvan, D K Subbakrishna
1Department of Psychiatry, NIMHANS, Bangalore 560 029, India. bng@nimhans.kar.nic.in
Acta Psychiatrica Scandinavica
|April 12, 2002
Summary
Infant mortality rates influence schizophrenia's age-at-onset gender differences. Higher infant mortality (IMR) correlated with later age-at-onset in males compared to females, suggesting survival bias.
Area of Science:
- Psychiatry
- Epidemiology
- Genetics
Background:
- Schizophrenia exhibits complex age-at-onset (AAO) patterns.
- Reversed gender effects on AAO have been observed, requiring explanation.
- Infant mortality rate (IMR) may play a role in observed gender differences.
Purpose of the Study:
- To investigate the hypothesis that higher infant mortality (IMR) explains the reversed gender effect on age-at-onset (AAO) in schizophrenia.
- To analyze the relationship between IMR and gender-specific AAO in schizophrenia patients.
Main Methods:
- Retrospective review of case records for schizophrenia patients (ICD-10) from two states with differing IMRs (13 and 67 per thousand).
- Calculation of AAO based on recorded age and duration of illness.
- Comparison of AAO between males and females across the two states.
Main Results:
- In the low IMR state, no significant difference in AAO was found between sexes.
- In the high IMR state, males exhibited a significantly older AAO than females.
- A fivefold higher IMR was associated with a reversed gender effect on AAO.
Conclusions:
- Gender differences in schizophrenia AAO may be influenced by perinatal complications and survival rates.
- High IMR environments may eliminate a subset of males with earlier AAO due to perinatal issues, altering the observed gender effect.
- IMR serves as a proxy for factors impacting survival of infants with perinatal complications, thereby affecting gender-specific AAO in schizophrenia.