The trajectory of non-depressed suicidal ideation in community-dwelling older people in a rural area in Japan: a prospective longitudinal study with a 3-year follow-up

Abstract

Background: Suicidal ideation is closely related to severe suicidal behaviour and is an important predictor of suicide attempt and completion, including in older people. Older people tend to have many opportunities to be conscious of death, and may have vague suicidal ideation because of various loss experiences, even if they are not depressed. We hypothesised that suicidal ideation among older people might be a risk factor for later transition to depression. The present study aimed to clarify risk factors that predict the incidence of depression in older people 3 years post-baseline in a rural area of Japan, and to examine the subsequent course of depression among non-depressed older people with suicidal ideation.

Methods: In 2015 and 2018, survey questionnaires were mailed to residents aged 65 years and over living in a rural area in Japan. Participants were divided into a depression group and a non-depression group using 15-item Geriatric Depression Scale scores 3 years post-baseline. Logistic regression analysis was used to identify predictive factors of late-life depression 3 years post-baseline.

Results: We received 597 valid responses, with a 3-year follow-up rate of 78.8%. Regarding suicidal ideation, 6.7% of non-depressed older people exhibited suicidal ideation at baseline. Of these, 9.8% exhibited depression after 3 years post-baseline. Logistic regression analysis indicated that development of late-life depression is significantly associated with suicidal ideation, being female, and poor health-related quality of life (HRQOL).

Conclusions: The results revealed that suicidal ideation, being female, and poor HRQOL were predictive factors of the development of late-life depression 3 years post-baseline in a rural area of Japan. These findings provide novel information regarding the transition to depression among community-dwelling older people who are not depressed but have suicidal ideation. Whereas suicidal ideation is considered to be a symptom of depression, the current results suggest that suicidal ideation may precede depression in some older people.

Keywords: cohort studies; depression; rural population; suicidal ideation.