Assessment of intellectual functioning in euthymic patients with bipolar disorder

The aim of the study was to assess the intellectual functioning of patients with bipolar disorder in remission and to delineate putative cognitive deficits in verbal and nonverbal functions and their associations with the course of illness.
Material and method: Fifteen patients with bipolar disorder (BD) in remission lasting for at least 4 months (4 male, 11 female; mean age 53.1±11.0 years; education level 13.0±3.2 years) and 15 age-, gender- and education-matched healthy controls were included. Mental state was assessed using the Hamilton Depression Rating Scale (HAMD), and Young Mania Scale (YMS). Mini Mental State Examination (dementia screening) and Wechsler Adult Intelligence Scale-Revised (WAIS-R) (assessment of intelligence quotient) were administered.
Results: Bipolar patients scored significantly lower than controls in full scale and Performance IQ (PIQ) of Wechsler Adult Intelligence Scale-Revised but not verbal measures of IQ. BD patients had significantly lower scores than controls in several performance subtests: Digit Symbols, Block Design, and Picture Completion suggesting visuospatial and perceptual organization dysfunctions. Bipolar patients also scored significantly worse on one verbal subtest. Similarities, which may be associated with abstract thinking difficulties in the patients group. Cognitive deficits were associated with the course of affective disorder including number of affective episodes, especially depressions.
Conclusions: Worse results in performance IQ in bipolar patients may suggest lateralized dysfunction of the right hemisphere (RH) which plays a significant role in visuospatial processing and perceptual organization of intellectual functioning.