No difference in the prevalence of Alzheimer-type neurodegenerative changes in the brains of suicides when compared with controls: an explorative neuropathologic study.

Abstract

Suicide ranks among the leading causes of death for individuals of all ages with highest rates in the elderly. The cause of suicide is considered a multifactorial phenomenon. A variety of neurodegenerative diseases, notably Alzheimer's disease, or, more recently, tauopathies as frontotemporal lobar degeneration or chronic traumatic encephalopathy, has been suggested as risk factor for suicide. Accordingly, we hypothesized that neurodegenerative changes typical of these diseases should be more prevalent in the brains of suicides when compared with controls. Suicides from the German federal state of Hamburg (n=162) were compared with age- and sex-matched controls who died of other cause. Neuropathological assessment included semiquantitative analysis of neuritic plaques and neurofibrillary tangles visualized with silver stains; in addition, quantitative immunohistochemical analysis of β-amyloid load and counts of tau-positive neurofibrillary tangles and neuropil threads was done. Univariate analysis and multivariable conditional logistic regression models did not show an effect of any parameter associated with the odds of committing suicide. On the contrary, after stratification for age, older suicide victims (over 48 years) showed lower β-amyloid loads when compared to controls in the univariate analysis (suicides: 4.7±12.9; controls: 9.9±20.9; p=0.031; r=-0.17). In conclusion, neuropathological characteristics of Alzheimer's disease and common tauopathies associated with age seem to be of limited relevance for suicides. However, intact cognition when planning and carrying out complex acts may be of importance in the context of suicide.