Is cognitive impairment associated with suicidality? A population-based study

Suicide is one of the main causes of mortality in young people and in individuals with depression. The impact of impaired cognitive function on suicidal ideation is largely unknown. The aim of this study was to examine how cognitive functioning may influence suicidal thoughts, both in the general population and in a subgroup of individuals with depression. A total of 4583 participants (aged 18 years and older) were interviewed in a cross-sectional study of a representative sample of the non-institutionalized Spanish population. Cognitive functioning was evaluated using five cognitive tests. Participants were also asked to provide information about mental health symptoms and conditions through an adaptation of the Composite International Diagnostic Interview (CIDI 3.0). Logistic regression analysis was performed overall and by age group. Lifetime prevalence of suicidal ideation was 3.7%, whereas prevalence of suicidal ideation in the previous 12 months was 0.9%. Depression was the strongest risk factor for suicidal ideation. Compared with people without suicidal ideation, people with suicidal ideas performed significantly worse on cognitive functioning after adjusting for age, years of education, gender, and the presence of depression. In the age-subgroup analyses, only the youngest group (18–49 years) showed a significant association between cognitive functioning and suicidal ideation. Worse cognitive functioning was also associated with more frequent suicidal ideas in those individuals with depression even when depression severity was taken into account. In conclusion, both cognitive functioning and diagnosis of depression are associated with higher risk of suicide in the Spanish general population, especially in young individuals.