Cognition in mania and depression

The inclusion of cognitive symptoms in the DSM-IV criteria for major depressive and manic episodes highlight the importance of cognition in both of these psychiatric disorders (American Psychiatric Association, 1994). For example, criteria for diagnosis of these conditions include a diminished ability to concentrate and indecisiveness. In addition, numerous studies have demonstrated wide-ranging cognitive deficits in depression (for example Elliott et al . 1996; Purcell et al . 1997; Murphy et al . 2003) and mania (Goldberg et al . 1993; Murphy et al . 1999, 2001; Sweeney et al . 2000). These include deficits in early information processing (Tsourtos et al . 2002), recollection memory (MacQueen et al . 2002) and planning (Elliott et al . 1996) as well as affective biases (Murphy et al . 1999) and abnormal responses to negative feedback (Elliott et al . 1996, 1997; Murphy et al . 2003). Some residual deficits are also evident in a proportion of remitted subjects, even when controlling for mood (for example, Clark et al . 2002).