There is a continuing debate about the differences and similarities between bipolar disorder (BD) and borderline personality disorder (BPD).

Only few studies have focused on the neuropsychological profile of these two disorders.

We studied the differences on memory, executive function and inhibitory control between BD and BPD patients.

Twenty-nine patients with BD in euthymia, 27 patients with BPD and 22 healthy controls matched for age and education were included in the study. All of them were female. BD patients who could also be diagnosed with BPD were excluded from the study. Participants were administered a series of tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB), accessing memory, executive function and inhibitory control.

BD and BPD patients performed worse than controls in general. Significant differences were found in the PAL test; BD patients had 46.71, BPD patients had 36.56 and controls had 15.77 errors (P=0.004). BPD patients performed worse in the IE/ED set-shifting test; they made 48.16 errors while BD patients made 23.64 and controls 16.14 (P=0.001). BPD patients performed better in the problem-solving task (SOC), they solved 10.0, BD patients 6.32 and controls 8.32 problems (P<0.001).

BD and BPD patients had similar performance in the SST inhibition task but worse than controls (P=0.03).

BD and BPD seem to have differences in neuropsychological performance. BD patients show more deficits in memory learning and problem solving while BPD patients show more deficits in set shifting.