Incidence of early-onset schizophrenia ‘increasing’

By Mark Cowen, Senior medwireNews Reporter

The incidence of diagnosed early-onset schizophrenia (EOS) has increased in recent years, study results show.

Furthermore, the previous predominance of male patients diagnosed with EOS has now switched to females, note Niels Okkels (Aarhus University Hospital, Aalborg, Denmark) and team.

The researchers used the Danish Psychiatric Central Research Register to investigate the incidence of EOS, defined as occurring before the age of 18 years, over 4 decades between 1971 and 2010.

Over the study period as a whole, the age-standardized incidence rate (IR) of EOS in the 0-18-year age group was 3.17 per 100,000 person years and 9.10 per 100,000 person years in those aged 12-18 years.

In the 0-18-year age group, the age-standardized IR of EOS was 1.80 per 100,000 person years in 1971-1993, rising to 5.15 per 100,000 person years in 1994-2010.

In the 12-18-year age group, the age-standardized IR of EOS was 5.02 per 100,000 person years in 1971-1993, rising to 15.73 per 100,000 person years in 1994-2010.

The overall age-standardized incidence rate ratio (IRR) for EOS in 1971-1993 was 0.034, with males having a significantly higher IRR than females, at 0.040 versus 0.027.

The overall age-standardized IRR for EOS in 1994-2010 was lower, at 0.013, but females had a significantly higher IRR than males, at 0.015 versus 0.011.

Okkels and team conclude: "We found a general increase in schizophrenia and all psychiatric disorders diagnosed before the age of 18 years over the study period of 4 decades."

They add: "The increase was probably caused by a combination of factors, for example, changes in diagnostic system, changes in organizational structure, drug abuse or more focus on child and adolescent psychiatric disorders in diagnostic practice.

"Last, but not least, our findings could be explained by a true increase in the number of persons developing psychiatric disorders."

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