Studies on the association between personality and BD are sparser, but have consistently shown higher levels on N and O and lower levels of C compared with normal controls.5, 6, 7, 8, 9 This suggests that subjects with MDD and BD are similar regarding N and C and differ regarding O. This is supported by studies directly comparing personality profiles for MDD and BD.5, 6, 8, 9 All studies showed the same trend with higher O in BD subjects than in MDD subjects. This was significant in only one of these studies,6 but the other samples included far fewer subjects and probably did not have the power to detect the effect (<100 BD subjects versus ∼1000 subjects).5, 8, 9 Most of these studies have been performed in MDD or BD subjects in an euthymic phase; thus, the results do not reflect a state effect of mood on personality.
