The influence of genetic loading on working memory performance in schizophrenia

Impaired working memory (WM) functioning is a common finding in schizophrenic patients. Healthy relatives of affected patients also show WM deficits when compared to control subjects without family history of schizophrenia. Thus, a strong genetic influence can be assumed, and WM functioning is considered as an endophenotype of the disease. In the present study, we investigated the effect of genetic loading on WM performance in schizophrenic patients. Patients were divided into two groups, one group consisting of patients with at least one more affected family member, and the other group without any affected relatives. Both patients and healthy control subjects performed a battery of 4 different WM-tasks and were compared with regard to their performance. Results: In the verbal WM-task which was performed by using verbal rehearsal, patients with family history of schizophrenia performed significantly worse compared to both control subjects and patients without family history. Similar results were found for another verbal and two visuo-spatial WM-tasks, though the differences between the patient groups did not reach the level of significance. Discussion: In spite of the low sample size (n=8 in each group) we found a significant influence of familial loading on working memory performance in schizophrenic patients. Especially the verbal rehearsal mechanism seems to be under strong genetic influence as it differentiates between patients with and without family history.