Disturbed social recognition and impaired risk judgement in older residents with mild cognitive impairment after the Great East Japan Earthquake of 2011: the Tome Project

Aim: After the Great East Japan Earthquake of 2011, we investigated the safety of residents in the affected communities. Most of the people requiring help were elderly and had previously been assessed as Clinical Dementia Rating (CDR) 0.5 (i.e. as having mild cognitive impairment (MCI)). We examined how well they understood the television news and whether they could make appropriate decisions. Methods: This community-based study of dementia and difficulties following a disaster started in Tome, northern Japan. The subjects were 188 randomly selected older residents who underwent CDR, blood tests, magnetic resonance imaging, and cognitive tests, including an original visual risk cognition task. They were shown NHK news broadcasts from the day of the earthquake to determine whether they could understand the content. Results: Neither the CDR 0 (healthy) nor the CDR 0.5 (MCI) subjects fully understood the television news. Some subjects did not recognize the danger of aftershocks and engaged in risky behaviour. CDR 0.5 subjects who exhibited such behaviour scored lower on the visual risk cognition task. Conclusions: It is noteworthy that television news is difficult to understand, even for healthy older adults. We found that MCI subjects had particular difficulties due to the disaster and suggest that risk cognition could be evaluated using visually presented materials.