This study presents three main findings. First, suicide risk in older adults who had received a diagnosis of cognitive impairment in the preceding year was significantly higher than in those without cognitive impairment. Second, regarding the subtypes of cognitive impairment, older adults with Alzheimer’s disease and other/unspecified dementia had a higher suicide risk compared to the non-cognitive impairment group. Finally, suicide risk in female and young-old adults with cognitive impairment was higher than in the comparison group.
In most previous studies, suicide risk in dementia or cognitive impairment was nonsignificant, which differs from our findings [14–17, 22]. Margda et al. (2002) showed that dementia was not associated with suicide in individuals ≥ 65 years . Harris and Barraclough (1997) showed that suicide risk is increased in all mental disorders except mental retardation and dementia . Wiktorsson et al. (2010) found that factors correlated with suicide attempts were living alone, being unmarried, history of psychiatric treatment, low educational level, and prior suicide attempts; no relationship with dementia was observed . Randall et al. (2014) reported that all mental disorders (depression, anxiety, substance use, and schizophrenia) except dementia were independently associated with suicide death . An et al. (2019) added up evidence for nonsignificant suicide risk associated with cognitive impairment . The most remarkable difference between our findings and those from previous studies pertains to the monitoring period for suicide risk after diagnosis. Previous studies implied that those who committed suicide might have had more preserved insight and less cognitive impairment at the time of death. In other words, better cognitive states enabling suicide execution and sustained insight into the diseases might increase the likelihood of suicide death in patients with dementia . By contrast, as per our results, suicide risk in patients with mild cognitive impairment was not associated with suicide deaths. We suggest that the early period after diagnosis is an important factor in the prediction of suicide risk in older adults with cognitive impairment.
Contrary to the nonsignificant results presented in most previous studies, Erlangsen et al. (2008) showed that adults with dementia are at a greater suicide risk compared to those without dementia . However, the results cannot be generalized to older adults without mental disorders. Our finding implies that diagnosis of cognitive impairment, not psychiatric disorders, increases the risk of suicide.
In our results regarding the subtypes of cognitive impairment, older adults with Alzheimer’s disease dementia were at a higher suicide risk, whereas vascular dementia was not significantly associated with suicide risk compared to the non-cognitive impairment group. Alzheimer’s disease and vascular dementia share many clinical signs and symptoms. Both are characterized by cognitive decline, functional deterioration, and neuropsychiatric symptoms that may present as behavioral alterations . However, some differences have been observed. Whereas memory and language function deficits prevail in Alzheimer’s disease, executive frontal lobe cognitive functions, such as attention, planning, and speed of mental processing, are more impaired in vascular dementia . Motor function is not as greatly affected by Alzheimer’s disease [34, 35] as by vascular dementia [36, 37]. We suggest that patients with Alzheimer’s disease who have relatively less impaired ability to plan and execute suicide are at higher risk for suicide death. In South Korean clinical circumstances, if specialists cannot clearly identify dementia, they tend to diagnose patients with other/unspecified dementia, which may include other psychiatric disorders. We find it difficult to elucidate the mechanisms underlying the reason why older adults with other/unspecified dementia are at an increased risk for suicide, suggesting the need for further research.
This study demonstrated that suicide risk in female and young-old adults with cognitive impairment was higher than in the comparison group. Previous studies in the general population reported that male and old-old adults were at a higher suicide risk [28, 38]. These results imply that the characteristics that influence suicide in older adults with dementia differ from those that are significant in the general elderly population, and suicide prevention strategies for older adults with cognitive impairment should be specifically tailored to their characteristics.
This study has several limitations. First, we could not determine cognitive impairment severity from the medical records. A previous study revealed that severity of cognitive impairment measured by Clinical Dementia Rating scale was not associated with suicide risk . Despite nonsignificant results, future research is warranted to explore suicide risk by specific period considering the severity of cognitive impairment. Second, although lifetime personal history of suicide attempts is a risk factor for death by suicide, our database had no information on individuals who attempted suicide . Finally, our study included only the South Korean elderly population. Therefore, caution needs to be exercised when generalizing the results to populations with dissimilar backgrounds (e.g., young populations or those in countries with lower suicide rates than South Korea).