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

Looking on bright side may reduce anxiety, especially when money is tight

December 17, 2018
Trying to find something good in a bad situation appears to be particularly effective in reducing anxiety the less money a person makes, possibly because people with low incomes have less control over their environment, according ...

Levels of gene-expression-regulating enzyme altered in brains of people with schizophrenia

December 14, 2018
A study using a PET scan tracer developed at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital (MGH) has identified, for the first time, epigenetic differences between the brains of individuals ...

Video game players frequently exposed to graphic content may see world differently

December 13, 2018
People who frequently play violent video games are more immune to disturbing images than non-players, a UNSW-led study into the phenomenon of emotion-induced blindness has shown.

Researchers discover abundant source for neuronal cells

December 13, 2018
USC researchers seeking a way to study genetic activity associated with psychiatric disorders have discovered an abundant source of human cells—the nose.

New genetic clues to early-onset form of dementia

December 13, 2018
Unlike the more common Alzheimer's disease, frontotemporal dementia tends to afflict young people. It accounts for an estimated 20 percent of all cases of early-onset dementia. Patients with the illness typically begin to ...

How teens deal with stress may affect their blood pressure, immune system

December 13, 2018
Most teens get stressed out by their families from time to time, but whether they bottle those emotions up or put a positive spin on things may affect certain processes in the body, including blood pressure and how immune ...

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.