Cognitive decline continues for years after the onset of schizophrenia and other psychoses, although it varies across cognitive functions and diagnoses, according to a study published online in The American Journal of Psychiatry.
“Schizophrenia is associated with a marked cognitive impairment that is widely believed to remain stable after illness onset. Yet, to date, 10-year prospective studies of cognitive functioning following the first episode with good methodology are rare,” researchers wrote.
“The authors examined whether schizophrenia patients experience cognitive decline after the first episode, whether this decline is generalized or confined to individual neuropsychological functions, and whether decline is specific to schizophrenia.”
The study followed patients with first-episode psychosis for up to a decade. Researchers administered neuropsychological tests at enrollment and again at follow-up about 10 years later to 65 participants with schizophrenia and 41 participants with other psychoses, as well as to 103 healthy participants used for comparison purposes.
According to a Psychiatric News Alert report on the study, patients with schizophrenia and other psychoses demonstrated greater impairment in IQ and some specific cognitive functions, compared with healthy participants at baseline. Those with schizophrenia showed the most impairment.
Over the course of follow-up, patients with schizophrenia showed continued declines in IQ, verbal knowledge, and memory, compared with healthy participants. While impaired at baseline, processing speed and executive function in patients with schizophrenia remained stable afterward.
Meanwhile, patients with other psychoses did not demonstrate continued declines in IQ, compared with healthy participants. They did, however, show some memory decline, according to the article.
Understanding the differences in cognitive decline among patients with schizophrenia and other psychoses can be used to inform cognitive remediation therapy, researchers advised.
Zanelli J, Mollon J, Sandin S, et al. Cognitive change in schizophrenia and other psychoses in the decade following the first episode. The American Journal of Psychiatry. 2019 July 1;[Epub ahead of print].