Low-dose acetylsalicylic acid (LDASA) may have some protective benefit against cognitive decline, but only if started well before symptoms begin, according to a retrospective analysis of two large cohorts. The association with all-cause dementia was weak, but much more pronounced in subjects with coronary heart disease.
The results underscore that individuals with cardiovascular disease risk factors should be prescribed LDASA, and they should be encouraged to be compliant. The study differed from previous observational and randomized, controlled trials, which yielded mixed results. Many looked at individuals older than age 65. The pathological changes associated with dementia may occur up to 2 decades before symptom onset, and it appears that LDASA cannot counter cognitive decline after a diagnosis is made. “The use of LDASA at this age may be already too late,” said Thi Ngoc Mai Nguyen, a PhD student at Network Aging Research, Heidelberg University, Germany. She presented the results at the 2021 Alzheimer’s Association International Conference.
Previous studies also included individuals using LDASA to prevent cardiovascular disease, and they didn’t always adjust for these risk factors. The current work used two large databases, UK Biobank and ESTHER, with a follow-up time of over 10 years for both. “We were able to balance out the distribution of measured baseline covariates (to be) similar between LDASA users and nonusers, and thus, we were able to adjust for confounders more comprehensively,” said Nguyen.
Not Yet a Definitive Answer
Although the findings are promising, Nguyen noted that the study is not the final word. “Residual confounding is possible, and causation cannot be tested. The only way to answer this is to have clinical trials with at least 10 years of follow-up,” said Nguyen. She plans to conduct similar studies in non-White populations, and also to examine whether LDASA can help preserve cognitive function in middle-age adults.
The study is interesting, said Claire Sexton, DPhil, who was asked to comment, but she suggested that it is not practice changing. “There is not evidence from the dementia science perspective that should go against whatever the recommendations are for cardiovascular risk,” said Sexton, director of scientific programs and outreach at the Alzheimer’s Association. “I don’t think this study alone can provide a definitive answer on low-dose aspirin and its association with dementia and Alzheimer’s disease, but it’s an important addition to the literature,” she added.
The researchers examined two prospective cohort studies, and combined them into a meta-analysis. It included the ESTHER cohort from Saarland, Germany, with 5,258 individuals and 14.3 years of follow-up, and the UK Biobank cohort, with 305,394 individuals and 11.6 years of follow-up. Subjects selected for analysis were 55 years old or older.
The meta-analysis showed no significant association between LDASA use and reduced risk of Alzheimer’s disease, but there was an association between LDASA use and all-cause dementia (hazard ratio [HR], 0.96; 95% confidence interval [CI], 0.93-0.99).
There were no sex differences with respect to Alzheimer’s dementia, but in males, LDASA was associated with lower risk of vascular dementia (HR, 0.85; 95% CI, 0.79-0.93) and all-cause dementia (HR, 0.87; 95% CI, 0.83-0.92). However, in females, LDASA was tied to greater risk of both vascular dementia (HR, 1.13; 95% CI, 1.02-1.24) and all-cause dementia (HR, 1.07; 95% CI, 1.02-1.13).
The strongest association between LDASA and reduced dementia risk was found in subjects with coronary heart disease (HR, 0.69; 95% CI, 0.59-0.80).
The researchers also used UK Biobank primary care data to analyze associations between longer use of LDASA and reduced dementia risk. Those who used LDASA for 0-5 years were at a higher than average risk of all-cause dementia (HR, 2.80; 95% CI, 2.48-3.16), Alzheimer’s disease (HR, 2.26; 95% CI, 1.84-2.77), and vascular dementia (HR, 3.79; 95% CI, 3.17-4.53). Long-term LDASA users, defined as 10 years or longer, had a lower risk of all-cause dementia (HR, 0.51; 95% CI, 0.47-0.56), Alzheimer’s disease (HR, 0.58; 95% CI, 0.51-0.68), and vascular dementia (HR, 0.48; 95% CI, 0.42-0.56).
Nguyen and Sexton have no relevant financial disclosures.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.