Literature Review

Stress-related disorders linked to later neurodegenerative diseases



Stress-related disorders may put individuals at increased risk of neurodegenerative conditions such as Alzheimer’s disease later in life, conceivably through a cerebrovascular pathway, according to authors of a large population- and sibling-matched cohort study. Individuals with posttraumatic stress disorder (PTSD), acute stress reaction, adjustment disorder, or other stress reactions had an 80% increased risk of vascular neurodegenerative diseases, according to results of the study, which was based on Swedish population registry data.

Risk of primary neurodegenerative diseases was increased as well in people with those conditions, but only by 31%, according to lead author Huan Song, MD, PhD, of Sichuan University in Chengdu, China.

“The stronger association observed for neurodegenerative diseases with a vascular component, compared with primary neurodegenerative diseases, suggested a considerable role of a possible cerebrovascular pathway,” Dr. Song and coauthors said in a report on the study appearing in JAMA Neurology.

While some previous studies have linked stress-related disorders to neurodegenerative diseases – particularly PTSD and dementia – this is believed to be the first, according to the investigators, to comprehensively evaluate all stress-related disorders in relation to the most common neurodegenerative conditions.

When considering neurodegenerative conditions separately, they found a statistically significant association between stress-related disorders and Alzheimer’s disease, while linkages with Parkinson’s disease and amyotrophic lateral sclerosis (ALS) were “comparable” but associations did not reach statistical significance, according to investigators.

Based on these findings, stress reduction should be recommended in addition to daily physical activity, mental activity, and a heart-healthy diet to potentially reduce risk of onset or worsening of cognitive decline, according to Chun Lim, MD, PhD, medical director of the cognitive neurology unit at Beth Israel Deaconess Medical Center in Boston.

“We don’t really have great evidence that anything slows down the progression of Alzheimer’s disease, but there are some suggestions that for people who lead heart-healthy lifestyles or adhere to a Mediterranean diet, fewer develop cognitive issues over 5-10 years,” Dr. Lim said in an interview. “Because of this paper, stress reduction may be one additional way to hopefully help these patients these patients that have or are concerned about cognitive issues.”

The population-matched cohort of the study included 61,748 individuals with stress-related disorders and 595,335 matched individuals without those disorders, while the sibling-matched cohort included 44,839 individuals with those disorders and 78,482 without. The median age at the start of follow-up was 47 years and 39.4% of those with stress-related disorders were male.

During follow-up, the incidence of neurodegenerative diseases per 1,000 person-years was 1.50 for individuals with stress-related disorders, versus 0.82 for those without stress-related disorders, according to the report. Risk of primary neurodegenerative diseases was increased among those with stress-related disorders, compared with those without, with a hazard ratio of 1.31 (95% confidence interval, 1.15-1.48). However, the risk of vascular neurodegenerative diseases was significantly higher, with an HR of 1.80 (95% CI, 1.40-2.31; P = .03 for the difference between hazard ratios).

Results of the matched sibling cohort supported results of the population-matched cohort, though the elevated risk of vascular neurodegenerative diseases among those with stress-related disorders was “slightly lower” than in the population-based cohort, Dr. Song and coauthors wrote in their report.

Beyond causing a host of hormonal and medical issues, stress can lead to sleep issues that may have long-term consequences, Dr. Lim noted in the interview.

“There’s some thought that quality sleep is important for memory formation, and if people are under a fair amount of stress and they have really poor sleep, that can also lead to cognitive issues including memory impairment,” he said.

“There are these multiple avenues that may be contributing to the accelerated development of these kinds of issues,” he added, “so I think this paper suggests more ways to counsel the patients about using lifestyle modifications to slow down the development of these cognitive impairments.”

Funding for the study came from the Swedish Research Council, Icelandic Research Fund; ,European Research Council the Karolinska Institutet, Swedish Research Council, and West China Hospital. Authors of the study provided disclosures related to those organizations as well as Shire/Takeda and Evolan.

SOURCE: Song H et al. JAMA Neurol. 2020 Mar 9. doi: 10.1001/jamaneurol.2020.0117.

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