[The role and importance of cognitive symptoms in bipolar disorder]

Our aim was to review evidence of the role of cognitive deficits in bipolar disorder and their relationship to other factors, such as disorder variables, treatment, additional diagnoses, genetic risk, and brain imaging findings.

Studies that examined cognitive dysfunction in bipolar disorder and its relationship to the variables of clinical, genetic, and bipolar disorder subtypes, as well as neuro-anatomical and neuro-functional evidence have been reviewed. Findings from our own studies have also been used while conducting the review.

In bipolar disorder, deficits in executive functions, memory, and attention persist in the euthymic state. The number of episodes and the course of the disorder seem to be related to the severity of memory dysfunction and psychomotor slowness. However, symptoms of cognitive dysfunction are present at the onset of the disorder. Moreover, cognitive dysfunction has been observed in the healthy relatives of bipolar disorder patients. Cognitive dysfunction in bipolar disorder is associated with functional and possibly structural anomalies in some parts of the brain, such as the frontal and cingulate cortex. Some recent studies reported a relationship between symptoms of cognitive dysfunction and genetic variations in bipolar disorder.

Today, the presence of cognitive deficits in bipolar disorder is widely accepted; however, evidence of the neurobiological and clinical correlates of cognitive symptoms is still limited. More studies are needed to investigate the relationship between cognitive dysfunction in bipolar disorder and risk. Genetic studies are just now amending our body of knowledge. There have been many conflicting results reported by brain imaging studies. Different brain imaging approaches and genetic methods should be used with more specific cognitive and social-emotional tasks for increasing our knowledge about the nature of cognitive deficit in bipolar disorder.