Cognitive impairment in patients with bipolar disorder alone versus those with bipolar disorder comorbid with borderline personality disorder.

Background: Bipolar disorder (BD) is a severe mental illness. BD often coexists with borderline personality disorders, making the condition more complex.

Aim: To explore the differences in cognitive impairment between patients with BD and those with BD comorbid with borderline personality disorder.

Methods: Eighty patients with BD and comorbid borderline personality disorder and 80 patients with BD alone were included in groups A and B, respectively, and 80 healthy volunteers were included as controls. Cognitive function in each group was evaluated using the Chinese version of the repeatable battery for the assessment of neuropsychological status (RBANS), the Stroop color-word test, and the Wechsler intelligence scale-revised (WAIS-RC).

Results: The indices of the RBANS, Stroop color-word test, and WAIS-RC in groups A and B were significantly lower than those of the control group (P < 0.05). Group A had significantly longer Stroop color-word test times for single-character, single-color, double-character, and double-color, lower scores of immediate memory, visual breadth, verbal function dimensions and total score of the RBANS, as well as lower scores of verbal IQ, performance IQ, and overall IQ of the WAIS-RC compared with group B (P < 0.05). Compared to group B, group A exhibited significantly longer single-character time, single-color time, double-character time, and double-color time in the Stroop color-word test (P < 0.05).

Conclusion: The cognitive function of patients with BD complicated with borderline personality disorder is lower than that of patients with BD.