Cognitive Functioning and

Bipolar I disorder is a severe and highly genetic psychiatric disorder characterized by depressive and manic episodes. Some bipolar patients show cognitive impairments, which may also be present in some of the patients ’ relatives. Using neuropsychological variables as endophenotypes, intermediate phenotypes between genes and the phenotypes, has been suggested to aid search for the etiological background of the disorder, but evidence is sparse on this subject. This population-based study examined cognitive functioning and their heritability in bipolar I disorder patients and in their unaffected relatives. Patients and their relatives had impairments especially in executive functioning and processing speed compared to controls. These functions were highly heritable in these families. Only patients were impaired in verbal memory, and the heritability was low in this function. Impaired processing speed contributed to other cognitive dysfunctions seen in patients. Processing speed, especially, may represent underlying vulnerability to the bipolar disorder, and be a valid endophenotype of the disorder. Impairment in verbal memory appears to be more related to fully developed disease. ISBN 978-952-245-457-7.!7BC5<2"HIHIKK