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The #1 Root Cause of Alzheimer's, Say Physicians

Up to 65% of people with Alzheimer’s have this in common.
FACT CHECKED BY Emilia Paluszek

According to the CDC, 5.8 million Americans are living with Alzheimer's disease (the most common form of dementia) as of 2020. "Alzheimer's disease is not an inevitable consequence of aging," says Brooks Kenny, executive director at WomenAgainstAlzheimer's and director of the Be Brain Powerful™ campaign. "Science is catching up, and there are things we can do to take care of our brain health and reduce our risks." Here are the main causes of Alzheimer's, including the #1 root cause, according to doctors. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


Sedentary Lifestyle

Tired senior hispanic man sleeping on dark blue couch, taking afternoon nap at the living room

Regular exercise can decrease the risk of developing dementia, doctors say. "Studies show that people who are physically active are less likely to experience a decline in their mental function and have a lowered risk of developing Alzheimer's disease," says Jonathan Graff-Radford, MD. "Physical activity is one of the known modifiable risk factors for dementia. Plus, regular exercise helps combat other Alzheimer's disease risk factors, such as depression and obesity."



Man and woman holding their bellies while sitting on the bed suffering from extra weight.

Obesity is strongly linked to an increased risk of Alzheimer's: One study shows people with a BMI of 30 or over had a 31% greater risk of dementia. "Dementia is one of the major health challenges of the 21st century that could threaten successful aging of the population," says Andrew Steptoe, FAcSS FMedSci MAE. "Our findings suggest that rising obesity rates will compound the issue. By identifying factors that may raise dementia risk that are influenced by lifestyle factors, we hope that a substantial portion, but admittedly not all, of dementia cases can be prevented through public health interventions."


Type 2 Diabetes

asian elder couple use blood glucose meter and worry about it

There is growing evidence that type 2 diabetes is linked to Alzheimer's disease. "One of the more intriguing hypotheses is that diabetes directly causes Alzheimer's disease," says Andrew E. Budson, MD. "Indeed, Alzheimer's disease has even been called 'type 3 diabetes' because of shared molecular and cellular features among diabetes and Alzheimer's. For example, insulin plays a critical role in the formation of amyloid plaques, and insulin is also involved in the phosphorylation of tau, which leads to neurofibrillary tangles. In other words, whereas insulin resistance in the body can lead to type 2 diabetes, insulin resistance in the brain can lead to the plaques and tangles of Alzheimer's disease."


Not Being Proactive

Doctor With Senior Patient Living At Home In Mask.

"There is growing evidence that adults in mid-life can take steps to lower their risk of dementia, including increasing physical activity and controlling health conditions like hypertension and diabetes," says Donovan Maust, MD, MS, geriatric psychiatrist specializing in dementia-related care. "Unfortunately, our findings suggest that people may not be aware of this and are not asking their doctor."


The #1 Root Cause of Alzheimer's

senior man consulting with doctor

A specific gene called APOE-e4 can substantially increase the risk of developing Alzheimer's disease, with up to 65% of people diagnosed shown to have it. "When a person has an increased risk for Alzheimer's due to their family history, I recommend specific functional testing that measures Alzheimer's-associated immune reactivity to identify the early stage of neurodegenerative processes and/or to monitor the effectiveness of lifestyle modifications for Alzheimer's disease," says Melanie Keller, MD. "In my practice, I order a test that includes a person's genetic (APO-E) status since one of the three forms (APOE-e4) is the first risk gene identified that remains the gene with the strongest impact on Alzheimer's risk."

Ferozan Mast
Ferozan Mast is a science, health and wellness writer with a passion for making science and research-backed information accessible to a general audience. Read more about Ferozan