IQ stabilization in childhood-onset schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Developmental Psychology

Background:

• Childhood-onset schizophrenia (COS) is a rare but severe form of schizophrenia.
• Understanding the long-term cognitive trajectory in COS is crucial for patient care and prognosis.
• Previous studies suggest cognitive decline in adult-onset schizophrenia, but data for COS is less established.

Purpose of the Study:

• To investigate the long-term intellectual quotient (IQ) trajectory in individuals with childhood-onset schizophrenia (COS).
• To determine if cognitive functioning remains stable over an extended period following psychosis onset in COS patients.
• To compare the IQ trajectory of COS patients with that of adult-onset schizophrenia patients.

Main Methods:

• A prospective longitudinal study involving 70 children diagnosed with schizophrenia.
• IQ testing conducted at 2-year intervals using age-appropriate Wechsler intelligence tests, including WISC subtests.
• Analysis of pre-illness IQ scores for a subgroup (31 patients) to establish baseline cognitive function.
• Mixed model regression analysis used to determine IQ performance patterns over time.

Main Results:

• No progressive cognitive decline was observed in COS patients up to 13+ years after psychosis onset.
• A subgroup with pre-illness scores showed an initial steep decline in IQ approximately 2 years before and 1.7 years after psychosis onset.
• Long-term IQ measures in COS remained stable, mirroring findings in adult-onset schizophrenia.

Conclusions:

• The long-term IQ trajectory in childhood-onset schizophrenia (COS) is stable.
• Cognitive functioning in COS patients remains at a consistent level for over 13 years post-psychosis onset.
• This cognitive stability in COS persists despite chronic illness and associated gray matter loss.