Neurofibrillary tangle pathology correlates with the activity of daily living of the house living aged population: A medicolegal aspect

The care of the aged population living at home is an urgent issue in the developed countries. It is important to investigate the factors in relation to the level of activities of daily life (ADL). It is also important to investigate the death situation in order to protect this population from accidental death. This study was undertaken to investigate whether the pathological change of the brain was one of the decisive factors of ADL and accidental death. Detailed information of ADL was obtained from the family and neighbors of 40 cases that were autopsied medicolegally at the medical examiner office of Osaka prefecture. The information regarding death situation was obtained from the coroner's documents. In each autopsied brain, senile plaques, neurofibrillary tangle (NFT), arteriosclerosis and ischemic changes of the brain were examined. Correlation between the neuropathological change, ADL and the death situation was statistically investigated. The severity and expansion of NFT, which was categorized as Braak's stage, showed significant correlation with ADL. Senile plaques and vascular change showed no significant correlation. Cases that had developed to Braak's isocortical stage showed a tendency to die in the bathroom or toilet. The NFT pathology of the limbic system has been shown to correlate with ADL. The damage of the limbic system might have an influence on the cognitive and behavior function of the brain and may lead to the reduced ADL. In addition, the NFT pathology may be a factor for the autonomic dysfunction and circulatory disorder. Therefore, the NFT pathology is considered to play a role in death during defecation and bathing.