Suicidal behaviours in affective disorders: a deficit of cognitive inhibition?

Suicide has been related to affective disorders. We hypothesized that suicide could be associated with cognitive inhibition deficit. Our study aimed to systematically review all published articles that examined the relation between cognitive inhibition deficit and suicidal behaviours (that is, suicide attempt or suicidal ideation) in patients with affective disorders.

We performed an English and French MEDLINE and EMBASE search, ranging from 1970 to 2010, indexed under the MeSH terms of suicide, neuropsychology, neuropsychological tests, and executive function, combined with the following title and abstract terms: neuropsychological functions, executive functioning, and executive performance.

Among the 164 selected studies, 9 observational studies met the selection criteria and were included in the final analysis. The number of participants ranged from 57 to 244 (28% to 66%, respectively, were men). Executive dysfunction was more frequently found among patients with suicidal behaviours. In particular, higher cognitive inhibition deficit was observed in depressed subjects with suicide behaviours, compared with depressed subjects without any suicidal behaviour. The results of the meta-analysis showed a higher impairment in inhibition score, according to the number of perseverations in the Wisconsin Card Sorting Test (Cohen d = 0.68) than in inhibition according to the time needed to perform the Trail-Making Test part B (d = 0.01) among patients with suicidal behaviour, compared with patients with no suicidal behaviour.

This systematic review and meta-analysis showed a positive association between cognitive inhibition deficit and suicide attempts in patients with affective disorders. Future research should examine whether cognitive inhibition deficit precedes the suicidal behaviour.