Joost Jannsen, PhD, of the Medical Imaging Laboratory, Hospital Gregorio Marañon, Madrid, Spain, and his colleagues analyzed cortical morphology in 92 youths between the ages of 11 and 18 years old. Twenty of the patients had early-onset first psychosis with schizophrenia, and another 20 with bipolar disorder. The remainder were healthy subjects.
Average lobar cortical thickness, surface area, gyrification index (GI) and sulcal width were compared between groups, and the relationship between the GI and sulcal width was assessed in the patient group. Gyrification refers to folding in the cerebral cortex as the brain grows.
Both the schizophrenia and bipolar patients had decreased cortical thickness and increased sucal width in the front cortex, compared to the healthy participants, the researchers reported in The American Journal of Psychiatry. The schizophrenia subgroup also had increased sulcal width in all other lobes.
“In adolescents with schizophrenia and bipolar disorder with psychotic symptoms there is cortical thinning, decreased GI and increased sulcal width of the frontal cortex present at the time of the first psychotic episode,” the researchers concluded. “These results suggest that abnormal growth (or more pronounced shrinkage during adolescence) of the frontal cortex represents a shared endophenotype for psychosis.
Recent evidence points to overlapping decreases in cortical thickness and gyrification in the frontal lobe of patients with adult-onset schizophrenia and bipolar disorder with psychotic symptoms, but it is not clear if these findings generalize to patients with a disease onset during adolescence and what may be the mechanisms underlying a decrease in gyrification.
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