Childhood psychiatric disorders linked to schizophrenia risk

By Eleanor McDermid, Senior medwireNews Reporter

Having a childhood psychiatric disorder increases people’s likelihood of being later diagnosed with schizophrenia, research shows.

“[K]nowledge about the risk of a subsequent diagnosis of schizophrenia following a psychiatric disorder in the childhood and adolescence might lead to earlier diagnosis and interventions, which can possibly lead to a better prognosis for individuals with schizophrenia”, say Cecilie Maibing (University of Copenhagen, Denmark) and study co-authors.

The team found that schizophrenia risk was highest in the year after receipt of a childhood psychiatric diagnosis, but remained significantly elevated more than 5 years later.

Among 603,348 people born in Denmark between 1990 and 2000, and followed up to a maximum of 22 years old, 25,138 individuals were diagnosed with a psychiatric disorder during childhood or adolescence. A total of 3085 people were diagnosed with schizophrenia, of whom 1232 also had a childhood psychiatric disorder.

The incidence rate ratio (IRR) for schizophrenia was 41.32 in the year after a childhood psychiatric diagnosis, relative to no diagnosis. The IRR declined to 14.53 at 1–2 years after diagnosis, 9.59 at 2–5 years and 4.93 for later time points, but remained significant. Affective/anxiety spectrum and obsessive–compulsive disorder (OCD) diagnoses had the most marked effect, especially in the first year after diagnosis, for which the IRR was 51.67.

“This may imply that the early pathways to schizophrenia truly go through child psychiatric disorders or that early signs of schizophrenia can mimic other disorders such as OCD, anxiety, and depression”, write Maibing et al in Schizophrenia Bulletin.

Other contributing factors could include misdiagnosis, chronic neuroinflammation or overlapping risk factors, symptoms and genetics, they add.

However, they note: “If shared risk genes are causing this highly elevated risk, these genes must affect many different disorders and not just one, because we found the risk to be elevated following all of the studied childhood psychiatric disorders.”

The effect of a childhood psychiatric diagnosis on the likelihood of receiving a schizophrenia diagnosis appeared greater in older than younger children. The cumulative incidence of schizophrenia diagnoses across the next 8 years among children who received a psychiatric diagnosis between the ages of 14 and 17 years was 8.74%, compared with 1.68% among those aged 13 years or younger at diagnosis.

However, when the researchers adjusted for both age at onset of the childhood psychiatric diagnosis and the time elapsed since this diagnosis, they found that age at onset did not influence the relationship between childhood psychiatric disorders and schizophrenia.

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