Patterns of impairment in executive functions within unipolar and bipolar depression

Abstract

IntroductionThe majority of studies revealed that cognitive deficits are an important aspect in many psychiatric illnesses, such as bipolar disorder and major depressive disorder. In the past, cognitive impairment was considered part of depression and it was expected to diminish as other mood symptoms improved with treatment.MethodThis study is based on the review of recent literature, performed in order to understand the dimension of executive impairment in unipolar and bipolar depression.ResultsBoth unipolar and bipolar depressed patients display cognitive deficits in several cognitive domains within executive functions. Different subcomponents of executive functions are altered in both types of patients, but impairments in sustained attention appear specific in bipolar depression while dysfunctional divided attention is reported in unipolar disorder. Studies describe deficits in planning strategies and monitoring processes that are characteristically impaired in unipolar depressed patients. Also these subjects tend to make more perseverative responses suggesting set shifting deficits and moreover they require longer time and more cognitive effort in order to accomplish tasks involving inhibitory control or cognitive flexibility. Other findings suggest that bipolar I depressed patients perform worse than bipolar II depressed patients and unipolar depressed patients across all executive functions especially in the decision making process that is considered to be a trait marker for bipolar disorder with no differences between the two types of bipolar subjects.ConclusionsExecutive functions represent a term that includes a higher order of cognitive abilities with deficits that are present in both disorders but display slightly different patterns of impairment.Disclosure of interestThe authors have not supplied their declaration of competing interest.