Elderly may face increased dementia risk after a disaster

October 24, 2016, Harvard T.H. Chan School of Public Health
Credit: CC0 Public Domain

Elderly people who were uprooted from damaged or destroyed homes and who lost touch with their neighbors after the 2011 tsunami in Japan were more likely to experience increased symptoms of dementia than those who were able to stay in their homes, according to a new study from Harvard T.H. Chan School of Public Health. The study was the first to look at dementia as a potential health risk in the aftermath of a disaster.

The study will appear online October 24, 2016 in an Early Edition of the Proceedings of the National Academy of Sciences journal (PNAS).

"In the aftermath of disasters, most people focus on like PTSD," said Hiroyuki Hikichi, research fellow at Harvard Chan School and lead author of the study. "But our study suggests that cognitive decline is also an important issue. It appears that relocation to a temporary shelter after a disaster may have the unintended effect of separating people not just from their homes but from their neighbors—and both may speed up cognitive decline among vulnerable people."

The Harvard Chan researchers, working with colleagues in Japan, were able to conduct a "natural experiment" among a group of elderly residents of the coastal city of Iwanuma, located about 80 kilometers west of the earthquake epicenter, where nearly half the land area was inundated by the tsunami. Seven months before the disaster, elderly residents of Iwanuma had been surveyed about their health as part of an ongoing study of aging called the Japan Gerontological Evaluation Study (JAGES). Two-and-a-half years after the tsunami, the researchers conducted a follow-up survey among the same group.

Out of 3,566 survivors of the tsunami disaster aged 65 or older—some who were able to remain in their homes and some who were forced out—38.0% said they lost relatives and/or friends and 58.9% reported property damage. In the pre-tsunami survey, 4.1% of respondents had been assessed with dementia symptoms; after the tsunami, the percentage jumped to 11.5%. The prevalence of stroke increased, from 2.8% to 6.5%, as did the prevalence of hypertension (54.0% to 57.2%). The percentage of people who reported not interacting with their neighbors—not even with greetings—nearly doubled, from 1.5% to 2.9%.

Those who wound up in temporary housing after their houses were either destroyed or sustained major damage had the highest levels of cognitive decline. There was a strong dose-response association: People whose houses were more severely damaged experienced more . Depression and declines in informal social interactions with friends and neighbors appeared to play a role in the link.

By contrast, loss of relatives and/or friends did not seem to impact cognitive abilities.

Explore further: A town where half the people have PTSD symptoms

More information: Increased risk of dementia in the aftermath of the 2011 Great East Japan Earthquake and Tsunami, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1607793113

Related Stories

A town where half the people have PTSD symptoms

March 6, 2014
Though just two of Hirono's 5,418 residents lost their lives in Japan's mega-earthquake and tsunami, a new study shows that the survivors are struggling to keep their sanity.

The social lives of the elderly mirror how they grow older

May 2, 2016
Small changes in the social lives of older people are early red flags showing that their thought processes and brain functioning could be on the decline. This is according to Ashwin Kotwal of Brigham and Women's Hospital ...

Vitamin D levels predict risk of brain decline in Chinese elderly

July 27, 2016
Research conducted by Duke-NUS Medical School (Duke-NUS) and Duke University has associated low vitamin D levels with increased subsequent risk of cognitive decline and impairment in the Chinese elderly.

Elderly Japanese most resilient in wake of triple disaster, study finds

July 19, 2016
Research into the aftermath of the Fukushima earthquake, tsunami and subsequent nuclear meltdown found that the oldest were least likely to experience a deterioration of existing chronic conditions.

Recommended for you

Modulating molecules: Study shows oxytocin helps the brain to modulate social signals

January 17, 2018
Between sights, sounds, smells and other senses, the brain is flooded with stimuli on a moment-to-moment basis. How can it sort through the flood of information to decide what is important and what can be relegated to the ...

Reducing sessions of trauma-focused psychotherapy does not affect effectiveness

January 17, 2018
Posttraumatic Stress Disorder (PTSD) patients treated with as few as five sessions of trauma-focused psychotherapy find it equally effective as receiving 12 sessions.

How past intentions influence generosity toward the future

January 17, 2018
Over time, it really is the thought that counts – provided we know what that thought was, suggests new research from Duke University's Fuqua School of Business.

Baby brains help infants figure it out before they try it out

January 17, 2018
Babies often amaze their parents when they seemingly learn new skills overnight—how to walk, for example. But their brains were probably prepping for those tasks long before their first steps occurred, according to researchers.

Tracking the impact of early abuse and neglect

January 17, 2018
Children who experience abuse and neglect early in life are more likely to have problems in social relationships and underachieve academically as adults.

Study: No evidence to support link between violent video games and behaviour

January 16, 2018
Researchers at the University of York have found no evidence to support the theory that video games make players more violent.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.