Profile of cognitive impairment in euthymic bipolar i patients: Relation to clinical characteristics

Background: Bipolar disorder has been identified as the sixth cause of disability among all medical illnesses, as it had been widely accepted that patients recovered completely and remain free in-between episodes. However, recent studies have shown that euthymic bipolar patients continue to have psychosocial difficulties and have reduced ability to regain premorbid levels of social and vocational functioning even after episodes of remission, suggesting that a gap exists between syndromal recovery and functional recovery, and this gap may be because of cognitive impairments. Cognitive deficits, most notably in attention, verbal learning, and executive function, can be observed across multiple phases of bipolar disorder. Aim of the study: To show the range of neuropsychological deficits in the various cognitive domains in euthymic bipolar I patients depending on the previous clinical state and to correlate these cognitive deficits with illness characteristics and profile. Participants and methods: This was a case-control study that included 60 patients divided into two major groups: a stratified random sample of 30 patients in the euthymic phase of bipolar I disorders and a control group. The patient group was diagnosed using Structured Clinical Interview for DSM-IV (SCID-I) and the euthymic state was determined using the Young Mania Rating Scale (YMRS) and the Hamilton Rating Scale for Depression (HRSD); we used Wechsler Adult Intelligence Scale (WAIS) and Wechsler Memory Scale- Revised (WMSR) for cognitive assessment. Results: Euthymic patients with bipolar I performed poorer than controls on tests of intelligence, attention, memory, and executive functions. Performance on most domains of Wechsler Adult Intelligence Scale (WAIS) was associated with age of onset of illness and the number of depressive episodes. These differences were statistically significant, with residual symptoms not reaching clinical significance. Conclusion: We conclude that cognitive deficits associated with euthymia in bipolar disorder can be considered both a consequence of the disorder and a determinant of outcome in recovery for bipolar I disorder.