TOPLINE:
In addition to better known risk factors such as diabetes, stroke, heart disease, and depression, findings of a large study suggested vitamin D deficiency, elevated C-reactive protein (CRP) levels, and social isolation increase the risk for young-onset dementia (YOD).
METHODOLOGY:
- The study included 356,052 participants younger than 65 years (mean baseline age, 54.6 years) without dementia from the UK Biobank, an ongoing prospective cohort study.
- Participants underwent a comprehensive baseline assessment, provided biological samples, completed touch screen questionnaires, and underwent a physical examination.
- Researchers identified incident all-cause YOD cases from hospital inpatient registers or death register linkage.
- The researchers detected 39 potential risk factors and grouped them into domains of sociodemographic, genetic, lifestyle, environmental, vitamin D and CRP levels, cardiometabolic, psychiatric, and other factors.
- Researchers analyzed incidence rates of YOD for 5-year age bands starting at age 40 years and separately for men and women.
TAKEAWAY:
- During a mean follow-up of 8.12 years, there were 485 incident YOD cases (incidence rate of 16.8 per 100,000 person-years; 95% CI 15.4-18.3).
- The final analysis identified 15 risk factors associated with significantly higher incidence of YOD, including traditional factors like stroke (hazard ratio [HR], 2.07), heart disease (HR, 1.61), diabetes (HR, 1.65), and depression (HR, 3.25) but also less-recognized risk factors like vitamin D deficiency (< 10 ng/mL; HR, 1.59), high CRP levels (> 1 mg/dL; HR, 1.54), and social isolation (infrequent visits to friends or family; HR, 1.53), with lower socioeconomic status (HR, 1.82), having two apolipoprotein E epsilon-4 alleles (HR, 1.87), orthostatic hypotension, which the authors said may be an early sign of Parkinson dementia or Lewy body dementia (HR, 4.20), and hearing impairment (HR, 1.56) also increasing risk.
- Interestingly, some alcohol use seemed to be protective (moderate or heavy alcohol use had a lower association with YOD than alcohol abstinence, possibly due to the “healthy drinker effect” where people who drink are healthier than abstainers who may have illnesses preventing them from drinking, said the authors), as was higher education level and higher than normative handgrip strength (less strength is a proxy for physical frailty).
- Men with diabetes had higher YOD risk than those without diabetes, while there was no association with diabetes in women; on the other hand, women with high CRP levels had greater YOD risk than those with low levels, while there was no association with CRP in men.
IN PRACTICE:
“While further exploration of these risk factors is necessary to identify potential underlying mechanisms, addressing these modifiable factors may prove effective in mitigating the risk of developing YOD and can be readily integrated in current dementia prevention initiatives,” the investigators wrote.
SOURCE:
The study was led by Stevie Hendriks, PhD, Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht, the Netherlands. It was published online in JAMA Neurology.
LIMITATIONS:
The study was observational and so can’t infer causality. Several factors were based on self-reported data, which might be a source of response bias. Factors not considered in the study, for example, family history of dementia and drug (other than alcohol) use disorder, may have confounded associations. Some factors including orthostatic hypotension had few exposed cases, leading to decreased power to detect associations. Hospital and death records may not have captured all YOD cases. The UK Biobank is overrepresented by healthy and White participants, so results may not be generalizable to other racial and ethnic groups. The analyses only focused on all-cause dementia.
DISCLOSURES:
The study was supported by Alzheimer Netherlands. Hendriks has no relevant conflicts of interest; see paper for disclosures of other authors.
A version of this article appeared on Medscape.com.