You’ve probably heard certain things about dementia: That there are four distinct types, and that dementia is mainly inherited. That thinking is changing.
Alzheimer’s Disease, Multiple Infarct Dementia, Lewy Body Dementia, and Frontotemporal Dementia are useful labels. They describe how certain dementias progress. They also remain somewhat useful in describing types of behavior associated with each.
But there’s less confidence now about how different each type is in terms of brain changes. There’s new evidence that behavior, lifestyle, and treatable medical issues may be as, or more, responsible than inheritance.
Since initial studies focused on obvious brain changes found in different types of dementia, researchers expected each type would require a different approach to treatment or prevention.
New findings show that the two most common types of dementia, Alzheimer’s and Multiple Infarct, are more similar than different, and genetics are proving to be a weak predictor. Only 21 percent of dementia is strongly inherited. The APOE-e4 “Alzheimer’s gene” is only suggestive of a greater risk, not certainty, of the disease. While some people with the abnormal gene progress to Alzheimer’s, others go on with only minor difficulties and many never develop problems.
By only looking at characteristic plaques and tangles in Alzheimer’s and small strokes in Multiple Infarct dementia, researchers missed key information. First, there are plaques, tangles and small strokes in both types, just more plaques and tangles than strokes in the Alzheimer’s brain, and more strokes than plaques in the Multiple Infarct brain. Second, there are plaques, tangles, and small strokes in folks who have no dementia at all.
Sister Bernadette, a Catholic nun, was part of the Nun Study, a follow-up study of brain health and aging begun in 1986. These nuns were chosen because they lived communally, therefore had similar diets and routines.
Sister Bernadette was given cognitive testing until age 84, with no signs of mental decline. When she died at 85, reports show her brain was “riddled with the plaques and tangles” that some are convinced cause Alzheimer’s.
Epidemiologist David Snowdon, who started the Nun Study wrote, “It was as if her neocortex was resistant to destruction for some reason… Sister Bernadette appears to have been what we, and others, have come to call an ‘escapee.’”
A drug approved in early June 2021 by the FDA to treat Alzheimer’s is being re-examined after three members of the advisory panel resigned when it was granted accelerated approval over their objections. The reason? The new and extremely expensive new drug, while shown to reduce plaques in patients with Mild Cognitive Impairment, was not subjected to trials that would have shown whether it prevented progression to Alzheimer’s. There’s still no evidence that it does.
The most common types of dementia share similar social, medical, and behavioral risk factors, however. These include smoking, heavy drinking, obesity, diabetes, high blood pressure, elevated levels of serum cholesterol, high intake of saturated fats, inadequate nutrition (especially low levels of vitamin B12 and folate), social isolation, lack of family interaction, depression, low levels of physical activity, cardiac disease, and poor sleep. So why not look at these risk factors as the best way to prevent dementia?
Some risk factors are interrelated. Poor diet contributes low nutrient levels, diabetes, and elevated cholesterol, and low social interaction and poor sleep are seen in depression, while smoking is associated with high blood pressure.
Controlling diabetes and blood pressure is tough without adequate finances. Family interaction is impossible for people with no family, and social isolation is an issue for people with poor mobility or no car. Quitting nicotine is hard, and many struggle with alcohol dependence. Social anxiety and social distancing also keep folks away from social interaction.
So far, the best nutritional advice is that a heart healthy diet is a healthy brain diet. Dietary guidelines from the American Heart Association are useful, and the same holds true for diabetes. Reaching out to the community can help with social isolation, and a counselor can help with depression. If your family history includes dementia, discuss medications with your physician.
More recently, the relationship between learning and continued mental activity is seen as an added layer of protection against dementia. Genetic aspects are looking more likely to be treatable with advances in biosciences.
There are scientifically sound ways to lessen your risk of dementia. Sister Bernadette, who “escaped” Alzheimer’s in the Nun Study, wrote every day. Thinking and memory improve with daily exercise.