This also applies to studies investigating the association between personality and MDD or BD. Most of these studies have focused on the personality traits neuroticism/negative emotionality (N), extraversion/positive emotionality (E)2, 3 and, to a lesser extent, agreeableness (A), conscientiousness (C) and openness to experience (O).2 ‘N' is commonly defined as a tendency toward emotional instability. ‘E' is characterized by a disposition toward positive emotions, gregariousness and the tendency to be active, seek out stimulation and enjoy the company of others. ‘O' involves active imagination, aesthetic attentiveness, variety preference and intellectual curiosity. ‘A' can be defined as the tendency to be cooperative and compassionate rather than suspicious and antagonistic toward others. Finally, the dimension ‘C' reflects traits of self-discipline, carefulness, thoroughness, organization, deliberation and achievement.2, 3
