Deficits in executive functions may play a leading role in late-life suicide behaviours.

To determine whether executive functions, and more specifically cognitive inhibition, could be associated with increased risk of suicidal behaviours among depressed elderly individuals.

We compared 10 depressed suicide attempters aged 65 and older with 10 depressed suicide non-attempters matched for age, gender and education. To assess cognitive inhibition, we used neutral material, in the form of the Modified Card Sorting Test (MCST), Go-No-Go task (GNG) and Stroop test (ST). The Brixton Spatial Anticipation test (BSA), the dual-task performance and verbal fluencies test were also used to assess flexibility, planning tasks and memory.

Suicidal (mean, 75.30 years; 70% female) and non-suicidal (mean, 72.90 years; 70% female) depressed groups were comparable in terms of burden of physical illness and severity of depression according to the Hamilton Depression Scale (mean score 27.90, p = 0.529). Suicide attempters showed greater impairments in cognitive inhibition as illustrated by significant between-group differences in the number of MCST errors (p = 0.023) and MCST preservative errors (p = 0.035), and by the trend of worse performance on GNG (p = 0.052). No significant differences were found in the scores on ST, BSA, dual-task performance and in semantic or phonemic verbal fluencies. Furthermore, suicide attempt was also associated with GNG score (adjusted Odds Ratio = 0.25 [95CI = 0.07–0.95], p = 0.041) after adjustment for age.

Our case-control study shows that poor cognitive inhibition is associated with suicidal behaviours in late-life depression.