Suicide and Alzheimer's pathology in the elderly: A case-control study

Background: The single most important risk factor for Alzheimer's pathology is age. Elderly individuals are also at increased risk for suicide, but comprehensive studies of the association between Alzheimer's pathology and suicide are lacking. We designed the current study to determine if Alzheimer's disease changes are overrepresented in elderly people committing suicide. Methods: The design is a case-control study. Cases (n = 28) were subjects older than 60 years of age who completed suicide. For each case, two age- and gender-matched individuals who died naturally were selected as control subjects (n = 56). Neuropathologic examination of hippocampal sections was performed blindly and included a modified Braak scoring system and semiquantitative assessment of neurofibrillary tangles, amyloid deposition, Lewy bodies, and Lewy-associated neurites. Data were analyzed by conditional logistic regression. Results: The brains of individuals who committed suicide had higher modified Braak scores than those of matching control subjects (p =. 0028). The number of neurofibrillary tangles in CA1 was not an independent predictor of suicide status in the statistical analysis (p =. 16), although the distribution was more highly skewed among the cases (75th percentile of 10.5 for cases, vs. 2 for control subjects). Conclusions: Severe Alzheimer's disease pathology is overrepresented in elderly patients who complete suicide.