March 11, 2020
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Individuals with stress-related disorders at increased risk for neurodegenerative diseases

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Huan Song

Stress-related disorders are associated with an increased risk for neurodegenerative diseases, according to results of a population-matched and sibling cohort study conducted in Sweden and published in JAMA Neurology. This association was particularly strong for vascular neurodegenerative diseases.

“Reducing the risk for cardiovascular diseases may subsequently reduce the risk for developing neurodegenerative diseases among patients with stress-related disorders,” Huan Song, MD, PhD, of Sichuan University in Chengdu, China, told Healio Psychiatry. “Doctors should be aware that if patients with stress-related disorders experience cognitive impairment and depressive symptoms, it may not be a part of their stress-related disorders but may signal dementia and Parkinson's disease.”

The researchers sought to examine the association between several stress-related disorders, including PTSD, acute stress reaction, adjustment disorder and other stress reactions, and subsequent risk for neurodegenerative diseases, including dementia, parkinsonian disorders and amyotrophic lateral sclerosis (ALS). They collected data from Swedish nationwide health registers, including the Swedish National Patient Register, and identified individuals who were first diagnosed with stress-related disorders between 1987 and 2008. Not included in the study were those who had a history of neurodegenerative diseases, had conflicting or missing information, had no data on family links or were aged 40 years or younger at the study’s end.

Song and colleagues compared individuals with stress-related disorders with the general population in a matched cohort design, as well as with their siblings in a sibling cohort. They followed study participants from age 40 years or 5 years after stress-related disorder diagnosis, whichever came later, until emigration, death, the first diagnosis of a neurodegenerative disease or Dec. 31, 2013, whichever came first. Further, the researchers identified neurodegenerative diseases using the National Patient Register and classified them as primary or vascular, and they evaluated Alzheimer’s disease, Parkinson’s disease and ALS separately.

inforgraphic of study author Song with quote
Source: Song H, et al. JAMA Neurology. 2020;doi:10.1001/jamaneurol.2020.0117.

The population-matched cohort included 595,335 matched unexposed individuals and 61,748 exposed individuals. The sibling cohort analysis included 44,839 exposed individuals and their 78,482 unaffected full siblings. At the start of follow-up, the median age was 47 years (interquartile range [IQR], 41-56) and nearly 40% of the exposed individuals were men.

Median follow-up was 4.7 years.

Results showed that individuals with a stress-related disorder had an increased risk for neurodegenerative diseases (HR = 1.57; 95% CI, 1.43-1.73) compared with unexposed individuals. Vascular neurodegenerative diseases (HR = 1.8; 95% CI, 1.4-2.31) were associated with a greater risk increase than primary neurodegenerative diseases (HR = 1.31; 95% CI, 1.15-1.48). The researchers reported a statistically significant association for Alzheimer’s disease (HR = 1.36; 95% CI, 1.12-1.67) but not for ALS (HR = 1.2; 95% CI, 0.74-1.96) or Parkinson’s disease (HR = 1.2; 95% CI, 0.98-1.47). Sibling cohort results corroborated those from the population-matched cohort.

“The findings of this cohort study appear to support the hypothesis that individuals with a stress-related disorder diagnosis are at an increased risk for developing a neurodegenerative disease later in life, independent of multiplied confounders such as familial factors,” Song and colleagues wrote. “The underlying mechanisms behind this association, primarily the role of cerebrovascular factors, warrant further studies.” – by Joe Gramigna

Disclosures: Song reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.