Diabetes, hypertension, and smoking linked to higher dementia risk

• There are many ways to help keep the vascular system healthy, such as not smoking and keeping blood pressure at a healthy level. 

• A new study has found a link between certain midlife vascular risk factors — specifically high blood pressure, diabetes, and smoking — and risk for dementia. 

• Scientists report the attributable vascular risk factors were higher in both female and Black participants, as well as non-carriers of the APOE ε4 gene, which is linked with an increased risk of Alzheimer’s. 

The vascular system refers to all the blood vessels that run through the body. These vessels are in charge of moving oxygen throughout the body and removing waste products.

There are several modifiable risk factors that can help keep your vascular system healthy, including not smoking, staying at a healthy weight, exercising, eating right, and keeping your blood pressure and cholesterol levels down.

If your vascular system is not functioning properly, it can increase your risk for vascular diseases such as aneurysm, peripheral artery disease, pulmonary embolism, and varicose veins.

Additionally, vascular disease can increase your chances of developing other health issues, including heart attack and stroke, and can worsen kidney disease.

Now, a new study recently published in the journal JAMA Neurology has found a link between certain midlife vascular risk factors — specifically high blood pressure, diabetes, and smoking — and risk for dementia. 

Scientists report the attributable vascular risk factors were higher in both self-identified female and Black participants, as well as non-carriers of the apolipoprotein ε4 (APOE ε4) gene.

Focusing on high blood pressure, diabetes, and smoking

For this study, researchers analyzed medical data from about 7,700 participants from the Atherosclerosis Risk in Communities (ARIC) study, which ran from 1987-2020 with a 33-year follow-up. Participant risk factors were measured at ages 45-54, 55-64, and 65-74 years old.

Researchers focused on three main vascular risk factors for this study: high blood pressure, diabetes, and smoking.

“There’s been pretty consistent research for decades that indicates the importance of these three vascular risk factors in midlife (~ age 45-64 years) for elevating dementia risk, with less consensus on their associations in late-life (~ age ≥75 years),” Jason R. Smith, PhD, ScM, who was at the time of the study a researcher in the Department of Epidemiology at Johns Hopkins Bloomberg School of Public Health in Maryland and first author of this study, told Medical News Today.

“The prevalence of vascular risk factors also remains high in adults. So interventions for vascular factors beginning as early as midlife could potentially avert a big chunk of dementia risk,” he said.

Up to 44% of dementia cases linked to vascular risk factors

Upon analysis, researchers found that between 22–44% of dementia cases reported by participants by age 80 were attributable to midlife and late-life vascular risk factors.

“That 22-44% of population-level dementia risk by 80 years was attributed to at least one vascular risk factor from midlife through early late-life (ages 45-74 years) signals a major prevention gap,” Smith explained. “Clinical and public health interventions targeting vascular risk beginning as early as midlife could delay or prevent a sizable fraction of dementia risk by 80 years.”

“The burden of dementia remains high,” he continued. “It has a heterogeneous presentation and pathology, so targeting risk factors that are modifiable, more proximal to dementia expression (including hypertension, diabetes, and smoking), and that could potentially impact more than one underlying process giving rise to dementia, is paramount to reduce population-level dementia risk.”

Higher risk in female, Black, APOE non-carrier participants

Additionally, scientists found that the vascular risk factor attributable risk was highest in participants who self-identified as female or Black, as well as those not carrying the APOE ε4 gene.

“Caution’s warranted when interpreting these stratified analyses, given wide (confidence intervals),” Smith said. “However, the analysis stratified by APOE carrier status suggests the absolute vascular contribution to dementia is larger among those at lower genetic risk for Alzheimer’s disease.”

“And that the vascular contribution was larger among those racialized as Black is likely due to a higher burden of vascular risk factors in this population,” he continued. “More inclusive and representative research is urgently needed to understand the prevention potential of vascular risk reduction in different populations.”

“While this study is not designed to provide evidence on individual-level dementia risk reduction, promoting optimal vascular health as early as midlife could be vital for reducing population-level dementia risk by 80 years,” Smith added. “What’s good for the heart is good for the brain, and the earlier prevention starts, the better.”

Vascular health necessary for a healthy brain

MNT spoke with Christopher Yi, MD, a board certified vascular surgeon at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, about this study.

Yi commented that this study reinforces an increasingly clear message: vascular health is brain health.

“My first reaction was that the findings were both striking and practical — nearly half of dementia cases by age 80 could be linked to modifiable vascular risk factors like high blood pressure, diabetes, and smoking,” he continued. “It’s especially notable that late-life vascular health appeared even more strongly associated with dementia risk than midlife health, which challenges the idea that ‘it’s too late’ to make a difference after midlife.”

Yi explained that vascular health affects dementia risk through several interconnected mechanisms.

“High blood pressure and vascular disease can damage the small vessels that supply the brain, leading to chronic ischemia (lack of oxygen) and brain tissue damage,” he detailed. “Silent strokes and microinfarcts are common in people with uncontrolled hypertension and diabetes and can accumulate over time, impairing cognitive function without obvious warning signs.”

For the next steps in this research, Yi said he would like to see more intervention trials, risk factor-specific analyses, mechanistic studies, and policy translation.

“Explore how these findings could support more aggressive screening and treatment of vascular risks in primary care, with cognitive outcomes in mind,” he added.

View the original article on Medical News Today