Our aims were to assess cognitive impairment in bipolar patients in remission compared with healthy controls, and to study its connection to clinical and therapeutic factors.

This was a case-control study of patients with bipolar disorder (BD) in remission and matched healthy controls. It was carried out at the Hédi Chaker University Hospital in Sfax, Tunisia. The Screen for Cognitive Impairment in Psychiatry (SCIP) scale was used to assess cognitive function in patients and controls. This scale comprises subtests for verbal learning with immediate (VLT-I) and delayed (VLT-D) recall, working memory (WMT), verbal fluency (VFT) and information processing speed (PST).

We recruited 61 patients and 40 controls. Compared with controls, patients had significantly lower scores on the overall SCIP scale and on all SCIP subtests (p < 0.001 throughout) with moderate to high effects. In multivariate analysis, the presence of psychotic characteristics correlated with lower scores on the overall SCIP (p = 0.001), VLT-I (p = 0.001) and VLT-D (p = 0.007), WMT (p = 0.002) and PST (p = 0.008). Bipolar II correlated with lower LTV-I scores (p = 0.023). Age of onset and duration of the disorder were negatively correlated with PST scores (p < 10^-3 and p = 0.007, respectively). Predominantly manic polarity correlated with lower VFT scores (p = 0.007).

Our study showed that bipolar patients in remission presented significantly more marked cognitive impairments, affecting various cognitive domains, than the controls. These cognitive impairments appear to be linked to clinical and therapeutic factors that are themselves considered to be factors of poor prognosis in BD.