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Post-disaster housing loss, financial strain, and healthcare disruption were linked to long-term cognitive decline in older adults after a tsunami.

Among older adults who survived the 2011 Great East Japan Earthquake and Tsunami, experiencing housing damage, worsening financial conditions, disruption in healthcare services, and a greater extent of overall damage were positively associated with cognitive deterioration, according to a study published in JAMA Network Open.

“The correlations between disaster damage exposures and cognitive decline suggest that interventions should address not only the immediate physical needs but also the long-term psychological and cognitive health of survivors,” wrote corresponding author Xiaoyu Li, ScD, and colleagues. “Cognitive training programs, mental health support, and community-based initiatives could play a critical role in mitigating cognitive decline.”

As part of the Japanese Gerontological Evaluation Study, community-dwelling adults aged 65 years and older in the coastal city of Iwanuma City, Japan, were invited to participate in a baseline survey in August 2010. The city was struck by the Great East Japan Earthquake and Tsunami 7 months later.

To track older adults’ cognitive disability trajectories over a decade after exposure to the natural disaster, researchers analyzed responses to follow-up surveys conducted in 2013, 2016, 2019, and 2022, and results from in-home evaluations.

The study included 1,988 older adults who were cognitively independent at baseline. Their average age was 72.4 years, and 58.3% were women.

Analysis identified three distinct cognitive disability trajectories participants demonstrated over the course of the study: (1) high levels of cognitive disability with increasing impairment over time (high and gradual deterioration), which affected 13.9% of participants; (2) low levels of cognitive disability with accelerated decline in cognitive function over time (low and progressive deterioration), which affected 27.2%; and (3) low levels of cognitive disability that remained stable (low and stable), which affected 58.9%.

With the low and stable trajectory as the reference, multinomial regression analysis found that high and gradual deterioration was associated with housing damage (researchers reported an adjusted odds ratio [AOR] of 2.52), worsening financial conditions (AOR of 1.83), and disruption in healthcare services (AOR of 1.76).

Meanwhile, low and progressive deterioration was linked with worsening financial conditions (AOR of 1.38) and higher composite damage scores (AOR of 1.16), according to the study.

Adjusting for postdisaster depressive symptoms dissolved the associations, the researchers wrote, “suggesting the importance of mental health support in the aftermath of such events.”