Risk factors for Alzheimer’s may appear early in life

Risk factors for Alzheimer’s disease (AD) may be present as early as adolescence and young adulthood, data presented at AAIC 2020 have shown, highlighting the importance of addressing these factors early in the fight against AD and other dementias.

“By identifying, verifying, and acting to counter [these] risk factors that we can change, we may reduce new cases and eventually the total number of people with AD and other dementias,” said Alzheimer’s Association chief science officer Dr Maria Carrillo, in a press release.

CV risk factors

In the STAR* study, 714 African-Americans were evaluated to establish the correlation between late-life cognition and cardiovascular (CV) risk factors during adolescence and early to mid-adulthood. Of these, 165 were adolescents (ages 12–20) while the rest were adults (n=439 young [ages 21–34] and 110 older adults [ages 35–56]). [AAIC 2020, abstract 47974]

After adjusting for age, gender, education, and years since risk factors were measured in both age groups, worse cognition was associated with hypertension and diabetes (pooled β, –0.18 and –0.69, respectively). Hypercholesteremia was tied to worse cognition in adults (β, –0.22), but not adolescents (β, 0.02). Having ≥2 CV risk factors predicted worse cognition for both age groups (pooled β, –0.24).

“African-Americans develop CVD risk factors at younger ages compared with other racial/ethnic groups … [These] results suggest that CV risk as early as adolescence influence late-life brain health in African-Americans,” said study co-author Dr Kristen George from the University of California in Davis, California, US.

Obesity and dementia

Another study investigated the role of early-life BMI on the risk of AD. The team pooled body mass index (BMI) data of 5,104 older adults from the CHS** and Health ABC*** studies (mean age at enrolment 72.6 years, 56 percent female). BMI was summarized by time-weighted averages in early (ages 20–49), mid (ages 50–69), and late life (ages 70–89). [AAIC 2020, abstract 37958]

After adjusting for mid- and late-life BMI in women, dementia risk increased with higher early-life BMI (odds ratios [ORs], 1.8 [overweight] and 2.5 [obese]) vs those with normal BMI.

In men, after adjusting for late-life BMI, dementia risk increased among those who were obese in early life (OR, 2.5), and among those who were overweight (OR, 1.5) and obese (OR, 2.0) in midlife.

“Our study is the first to report heightened dementia risk with higher early-life BMI, for both women and men,” said study co-author Dr Adina Zeki Al Hazzouri from Columbia University in New York City, New York, US.

It pays to start early

Taken together, these findings imply that the periods of adolescence and young adulthood may be a starting point for poor brain health. As such, investigators of both trials concurred in underpinning the importance of promoting healthy lifestyles early on in life to mitigate the potential deleterious impact of the above-noted health risk factors to the brain in later life.

“[These studies are] important in addressing health inequities and providing resources that could make a positive impact on a person’s life … These new reports … show that it’s never too early, or too late, to take action to protect your memory and thinking abilities,” said Carrillo.

The Alzheimer’s Association is leading the US POINTER^# trial to determine if lifestyle interventions simultaneously targeting several risk factors have a protective effect against cognitive decline in older individuals.