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In 2019, the estimated number of global dementia cases totaled 57.4 million. That number is expected to nearly triple by 2050. Given the predicted surge in incidence and the lack of substantial treatment options, research into potential risk factors to help avoid the condition is being closely monitored. Recently, investigations into associations with herpes zoster (see Info graphic below), social isolation, and the use of certain medications have been explored. Those findings resulted in dementia once more becoming the top trending clinical topic of the week.
Using Danish medical registries, researchers identified 247,305 people who had visited a hospital for herpes zoster or who were prescribed antiviral medication for herpes zoster over a 20-year period. They were then matched to 1,235,890 people who did not have herpes zoster. Contrary to anticipated findings, herpes zoster infection was associated with a small (7%) decreased relative risk for all-cause dementia during follow-up (hazard ratio [HR], 0.93; 95% CI, 0.90-0.95). No increased long-term risk for dementia was found in subgroup analyses, except possibly among those with an infection that involved the central nervous system (HR, 1.94; 95% CI, 0.78-4.80). However, the fraction of dementia attributable to this rare complication was low (< 1%), suggesting that universal vaccination has limited potential to reduce dementia risk. Nonetheless, researchers suggest that herpes zoster vaccination should be encouraged in older-adult populations because it can prevent complications.

One dementia risk factor that has been confirmed recently is social isolation. Results of a large, prospective, epidemiological study show that individuals who reported feeling socially isolated had a worse cognitive function at baseline and were more likely to develop dementia. Researchers examined data from 462,619 people (average age, 57 years) across the United Kingdom. At baseline, 9% reported being socially isolated and 6% reported feeling lonely. Compared with controls, those who felt isolated and/or lonely had a worse cognitive function at baseline after controlling for age, ethnicity, sex, education, and income. After a mean follow-up of 11.7 years, 4998 participants developed dementia. The incidence was 26% higher among those who had reported being socially isolated (adjusted odds ratio, 1.26; 95% CI, 1.15-1.37). MRI scans from about 32,263 participants conducted around 9 years after study onset revealed that those with higher levels of social isolation were more likely to have lower gray matter volume (GMV) in areas of the brain linked to learning and memory. No link was found between reported feelings of loneliness and dementia or GMV, which contradicts earlier findings.

Results were split on links with two different drug classes. A recent study found that opioid use in the elderly is associated with an almost 40% increased risk for dementia. The research included 91,307 Israeli citizens aged 60 years or older. During the study, 3.1% of participants were exposed to opioids at a mean age of 73.94 years and 5.8% developed dementia at an average age of 78.07 years. The risk for incident dementia was significantly increased in those exposed to opioids vs unexposed individuals in the 75- to 80-year age group (adjusted hazard ratio [AHR] 1.39; 95% CI, 1.01-1.92; Z-statistic = 2.02, P < .05).

The news was far better regarding dementia and proton pump inhibitor (PPI) use, even if questions about potential associations remain. In findings from a study presented on May 23 at Digestive Disease Week (DDW) 2022, no association was found between the use of PPIs or histamine H2 receptor antagonists (H2RAs) and a greater likelihood of incident dementia, Alzheimer’s disease, or cognitive decline in people older than 65 years. The research data come from ASPREE, a large aspirin study of 18,846 people older than 65 years in the United States and Australia. During 80,976 person-years of follow-up, 566 incident cases of dementia were identified. Baseline PPI use, in comparison with nonuse, was not associated with incident dementia (HR, 0.86; 95% CI, 0.70-1.05).
A potential means of identifying those at risk for dementia may involve bone density scans. In an analysis of more than 900 study participants, women in their 70s with more advanced abdominal aortic calcification (AAC) seen on lateral spine images during dual-energy x-ray absorptiometry (DEXA) had a higher dementia risk. Compared with women who had low AAC, women with moderate and extensive AAC were more likely to experience late-life dementia hospitalization (9.3% low, 15.5% moderate, and 18.3% extensive) and death (2.8%, 8.3%, and 9.4%, respectively). After multivariable adjustment, women with moderate AAC had a two- and threefold increased relative risk for late-life dementia hospitalization or death compared with their peers who had low AAC. Researchers suggest that bone densitometry scans may be a novel, noninvasive, and scalable way to identify older women at risk of developing dementia.

Beyond new means of targeting risk, the concern is high that many Americans are not taking enough steps to prevent dementia by reducing known modifiable risk factors. Data from the Centers for Disease Control and Prevention show that nearly half of all US adults aged 45 years or older have modifiable risk factors for Alzheimer’s disease and related dementia (ADRD), including hypertension, low levels of physical activity, and obesity. More than one-third (35%) of adults had obesity, 19% had diabetes, 18% had depression, 15% smoked, and 10% binge drank. More than 1 in 10 (11.3%) adults surveyed reported a subjective cognitive decline (SCD), an early indicator of possible future ADRD. The prevalence of SCD increased from about 4% among adults with no modifiable risk factors for ADRD to 25% for those with four or more risk factors.

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Written by Ryan Syrek

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