Cognition in high-risk groups

Who are people at high-risk of psychosis?

There are two key approaches for identifying people with early signs that may suggest a high risk of developing psychosis or schizophrenia. The first approach is based on Huber’s Basic Symptoms, which focuses on a detailed way of describing phenomenological (subjective) disturbances. Because the basic symptoms refer only to subtle subjectively experienced abnormalities, they may reflect an earlier phase in the disease process than the second approach, which identifies at-risk mental states as a combination of; a family history of psychosis (familial risk) plus non-specific symptoms and recent decline in functioning; recent onset Attenuated Psychotic Symptoms with decline in functioning; and Brief Limited Intermittent Psychotic Symptoms.

What is the evidence for cognitive functioning in high-risk groups?

High quality evidence shows small to medium-sized effects of poorer general intelligence, executive functioning, attention, visual memory, and social cognition in people at high risk of psychosis compared to controls. Moderate to high quality evidence also suggests poorer visual-spatial ability, olfactory functioning, verbal fluency, verbal memory, working memory, learning, processing speed and reasoning.

High quality evidence finds people at clinical high risk of psychosis and familial high risk of psychosis are similarly impaired on processing speed, verbal and visual memory, attention and language fluency when compared with controls. People at familial high risk were more impaired on premorbid and current IQ than those at clinical high risk, and those at clinical high risk were more impaired on visuospatial working memory than those at familial high risk.

Moderate to high quality evidence found large effects of poorer speed of processing and poorer verbal learning in people at high risk of psychosis who converted to psychosis when compared to controls. There were also medium to large effects of poorer visual learning, working memory and IQ, and medium-sized effects of poorer attention and reasoning in converters. Moderate quality evidence found converters also showed medium-sized effects of poorer olfactory functioning, language functioning, visual-spatial ability, and executive functioning. In non-converters, there were medium-sized effects of poorer verbal learning and current IQ, and small effects of poorer attention, reasoning, speed of processing and premorbid IQ. There were no differences in visual learning and working memory in non-converters.

Compared to people with first-episode psychosis, moderate to high quality evidence shows medium-sized effects of better attention, verbal learning, and working memory, and small effects of better current IQ and speed of processing in people at clinical high-risk of psychosis.

July 2019

Last updated at: 4:09 am, 26th July 2019
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