Personality disorders are defined by experiences and behaviours which deviate from societal norms and expectations. People diagnosed with a personality disorder may experience difficulties in cognition, emotiveness, interpersonal functioning or control of impulses. Personality disorders are inflexible and pervasive across many situations, due in large part to the fact that such behaviour may be ego-syntonic (the patterns are consistent with the ego integrity of the individual) and are, therefore, perceived by the individual to be appropriate. DSM-V lists ten personality disorders grouped into three clusters:

– Cluster A (odd or eccentric disorders): paranoid personality disorder, schizoid personality disorder, schizotypal personality disorder.

– Cluster B (dramatic, emotional, inconsistent or unpredictable disorders): antisocial personality disorder, borderline personality disorder, histrionic personality disorder, narcissistic personality disorder.

– Cluster C (anxious or fearful disorders): avoidant personality disorder, dependent personality disorder, obsessive-compulsive personality disorder.