Nov. 1, 2001 -- Although genetics are known to play a part in the development of mental illness, a new British study reveals that environment may also have a significant role. When researchers compared adults who had just been diagnosed with schizophrenia, they found that a significant number of them had been raised in poverty.
The study was published in the October issue of The British Journal of Psychiatry.
Over the course of two years, the team looked at about 100 adult men and women born in Nottingham county, England, when they first sought medical help for a psychotic episode. Using birth certificates and other public records, the researchers matched these individuals with another 100 or so people of the same age, race, and gender who were also born and raised in Nottingham.
The researchers divided the county into zones based on average family income, rates of unemployment and crime, and housing costs and conditions. They then divided everyone in the study into two broad socioeconomic classes based on where in Nottingham their mother lived, and their father's occupation, at the time of their birth.
They found that people whose fathers held more menial jobs, or were raised in poorer parts of Nottingham county, were twice as likely to develop schizophrenia in adulthood as those whose fathers held more professional positions, or were raised in more-affluent areas.
The findings show that "indicators of social inequality at birth are associated with increased risk of adult-onset schizophrenia," the researchers report. The findings also suggest "that environmental factors are important determinants of schizophrenic disorders."
The authors suggest several explanations for the link between childhood deprivation and adult mental illness. Physical risks, such as exposure to infections and other toxic agents, could be responsible, as well as living under the social and psychological stress of being poor and in need.
But environment is by no means the whole story. Most likely, they conclude, schizophrenia and other mental illnesses develop as a result of "complex gene-environment interactions."