A STUDY OF COGNITIVE FUNCTION IN NIGERIAN PATIENTS WITH SCHIZOPHRENIA, THEIR FIRST-DEGREE RELATIVES AND HEALTHY CONTROLS.

Background: Schizophrenia is a severe psychiatric condition with cognitive symptoms infrequently assessed clinically, yet, they impact the functioning of patients. Cognitive impairments have been found more in unaffected relatives of patients with schizophrenia, compared to healthy controls, suggesting them as endophenotypes of schizophrenia. There are few studies in Nigeria and Africa on these.

Objective: To assess cognitive functioning and its correlates in patients with schizophrenia, their first-degree relatives, and healthy controls.

Methods: 120 participants in each of the three groups were matched accordingly and assessed with the Brief Assessment of Cognition in Schizophrenia (BACS), Observable Social Cognition: A Rating Scale (OSCARS), Brief Negative Symptom Scale (BNSS), and other clinical scales. Standardized z-scores were calculated as appropriate.

Results: Patients had significantly greater cognitive impairment (p < 0.001) and poorer functioning (p < 0.001) compared to the other two groups. Relatives had worse cognitive impairment than controls, without a significant difference between them. Prevalence of cognitive impairment was 68.3%, 32.5%, and 28.3% for patients, relatives, and controls respectively (p ≤ 0.001). Worse patient clinical state, including negative symptoms and use of anticholinergics, were associated with poorer cognitive performance.

Conclusions: This study provided needed Nigerian data on cognitive function using standard brief instruments. The results affirm cognitive deficits as significant symptoms in patients with schizophrenia and also as possible endophenotypes of the disorder. Modifiable correlates of cognitive impairment were identified. More routine clinical assessment of cognitive function and research for possible treatments for cognitive impairments are necessary. Continued search for endophenotypes or other predictors of individuals at risk of schizophrenia should be encouraged.