Vitamin D deficiency, depression and social disadvantage are among the modifiable factors that can increase the risk of developing dementia in early life, according to a study led by the University of Exeter. The study found that the risks associated with developing dementia in midlife can be reduced through health and lifestyle interventions.
Although dementia is most common in older people, its impact on employment, social life and family relationships is particularly severe for those under 65 years of age. According to Alzheimer's UK, more than 70,800 people in the UK are living with young-onset dementia. However, because it is thought to be a disease of older ages, poor recognition and misdiagnosis mean the prevalence of dementia before age 65 is likely to have been "grossly underestimated".
Most previous studies have focused on genetic factors; however, genetic factors account for only 5% to 10% of cases of young-onset dementia.
For the study, published in JAMA Neurology, researchers analyzed data from 356,052 people in the UK Biobank. Participants were under 65 years of age and did not have a diagnosis of dementia at baseline assessment between 2006 and 2010, and were on average 54.6 years old.
Incidence rates increased with age across 5-year age groups and were higher in men than women.
Most risk factors are “potentially modifiable.” These factors included: lower formal education, lower socioeconomic status, presence of two apolipoprotein ε4 alleles, no alcohol consumption, diagnosed alcohol use disorder, social isolation, vitamin D deficiency, high levels of C-reactive protein, lower hand grip strength , hearing loss, orthostatic hypotension, stroke, diabetes, heart disease and depression. In contrast, any alcohol consumption, whether moderate or heavy; formal education to degree level and less physical frailty (using higher hand grip strength as a proxy) were associated with lower incidence of young-onset dementia.
Most risk factors are potentially modifiable, which the researchers said indicates that "targeted interventions may be effective in preventing dementia in midlife people" and should be included in future dementia prevention initiatives.
Study co-author David Llewellyn, professor of clinical epidemiology and digital health at the University of Exeter Medical School, said the study was the largest and most robust ever undertaken.
Co-author Dr Janice Ranson, senior research fellow at the University of Exeter, said: " Our study breaks new ground that the risk of developing young-onset dementia can be reduced. We believe this could usher in a new era of interventions to reduce new cases of the condition."
The study was part-funded by Alzheimer's Research UK, whose head of clinical research, Dr Lia Mursalin, said that "we are witnessing a transformation in understanding the risk of dementia and, potentially, how to reduce it at both an individual and societal level."
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