Lower Income at Birth
Linked to Schizophrenia Risk

NEW YORK (Reuters Health) - Being born into a lower-income family may raise a person's risk of developing schizophrenia later in life, UK researchers report.

Schizophrenia is a chronic psychiatric disorder in which patients have altered perceptions of reality, experience delusions and hallucinations, and lose their normal ability to communicate and respond emotionally.

The disorder runs in families, but genes are not the sole risk factor. Experts believe genes combine with developmental and environmental factors to trigger schizophrenia.

Investigators have long noted a relationship between lower socioeconomic status and schizophrenia, but it is not fully clear if social status contributes to the disorder. The link could instead reflect the ``social segregation'' that occurs once patients start having debilitating symptoms, note Glynn Harrison of the University of Bristol and colleagues.

But in their study comparing schizophrenics with the general population, the researchers found that social status at birth was linked to the risk of developing the disorder.

``These data add to accumulating evidence for the role of environmental factors in the (cause) of schizophrenia,'' Harrison and colleagues report in the October issue of the British Journal of Psychiatry.

Over 2 years, Harrison's team identified 168 patients being treated for psychotic symptoms for the first time. The patients' ranged in age from 16 to 64; half were younger than 25.

To delve into how their families' social status could have played a role, the researchers looked at their fathers' ``social class'' and the neighborhood their mothers lived in at the time they were born. The investigators then compared each patient with four individuals from the general population matched for age and sex. All were born in Nottingham and were living there at the time of the study.

Individuals whose fathers were of a lower social class--determined by their occupations--and those born in ''deprived'' areas had twice the risk of developing schizophrenia as others in the study, according to the report.

``Indicators of social inequality at birth are associated with increased risk of adult-onset schizophrenia, suggesting that environmental factors are important determinants of schizophrenic disorders,'' Harrison's team writes.

The researchers point to limitations of the study, however--including the fact that lower-income individuals may have been more likely to remain in Nottingham, while more affluent residents may have moved before developing schizophrenia. The disorder usually becomes apparent in the late teens and 20s.

And, they note, any effect of social status must be looked at in the context of other risk factors for schizophrenia. ``It is probable,'' they write, ``that causal relationships in schizophrenia are mediated by complex gene-environment interactions.''

SOURCE: British Journal of Psychiatry 2001;346-350.

Reference Source 89

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