The uprooting and isolation caused by the tsunami and the Fukushima nuclear disaster in Japan have increased the risk of dementia among the elderly.
On March 11, 2011, at 2:46 p.m., the Japanese coast was hit by a violent tsunami generated by a magnitude 9 earthquake. The 10-meter-high waves swept away everything in their path and flooded the Fukushima nuclear power plant. The disaster left 15,893 dead, 2,565 missing and thousands displaced. Five years later, the devastation still has repercussions on the populations, in particular the oldest, reveals a study published in Proceedings of the National Academy of Sciences journal (PNAS).
Isolated and uprooted seniors are, in fact, more at risk of suffering from dementia than those who have been able to stay in their homes. “In the aftermath of the disaster, most scientists focused on the psychological consequences such as post-traumatic stress,” notes Hiroyuki Hikichi, researcher at Harvard Chan School of Medicine, and lead author of the work. But our study suggests that cognitive decline is an important consequence. It appears that the temporary placement in a shelter had unexpected effects on the people forced to leave their homes but also on their neighbours. This accelerated cognitive decline in vulnerable people.”
To shed light on this consequence, the American researchers collaborated with their Japanese counterparts who had launched a study with elderly people 7 months before the tsunami. These seniors lived in Iwanuma 80 km from the epicenter of the earthquake. Almost half of the region had to be evacuated. They agreed two and a half years after the disaster to participate in the Japanese-American study.
One in 10 is affected by dementia
Of the 3,566 survivors aged 65 or over, nearly 4 in 10 lost family members or loved ones, and nearly 6 in 10 had their homes destroyed by the waves. Before the disaster, only 4.1% of participants had symptoms of dementia compared to 11.5% years after. The prevalence of stroke, the second leading cause of dementia, increased from 2.8% to 6.5%. Similarly, arterial hypertension affects more than 57% of the volunteers against 54% before the disaster.
According to the researchers’ analysis, seniors placed in shelters are those who show the most significant cognitive decline. And the more their houses were damaged, the more severe these consequences were. On the other hand, elderly people who have lost loved ones do not have a negative impact on their intellectual abilities.
For the researchers, the seniors were the most affected because they remained on the spot, close to the stigmata of the event. While their children, or young neighbors, have been able to rebuild their lives elsewhere.
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