The more than 11 million people nationwide providing unpaid care for a family member or friend with dementia — and countless others worried about cognitive decline — should see a beacon of light in the growing defense arsenal. In January, the U.S. Food and Drug Administration approved a drug that prevents amyloid plaque from clumping in the brain. In 2021, the FDA approved the first monoclonal antibody to treat Alzheimer’s disease; that one removes amyloid plaques in the brain. Prior to June 2021, physicians relied on five drugs to treat Alzheimer’s — each aimed at addressing symptoms and not toward changing the underlying biology of the disease.

Alas, clouds drift into the picture. According to the Alzheimer’s Association, about one in nine people 65 and older suffers from Alzheimer’s. Given the aging factor of the U.S. population, the number of dementia patients could more than double within four decades — from 6.7 million this year to 13.8 million in 2060. Not to be discounted is the report’s estimate that about 110 of every 100,000 U.S. residents age 30 to 65 have “younger-onset” Alzheimer’s. Most alarming is that the National Center for Health Statistics notes that the cause of death from Alzheimer’s soared more than 145 percent from 2000 to 2019.

On the brighter side, the Lancet Commission, in a 2020 update of its report on dementia, recognized a range of “modifiable risk factors” — giving people methods for preventing cognitive decline through behavioral shifts. Risk factors identified account for around 40 percent of worldwide dementias. Following are key takeaways from aggregate studies.

For a brain to fire on all cylinders, it needs to be maintained as a well-oiled machine. Activities that engage the mind — socializing and pursuing the arts, learning, problem-solving, etc. — build neural pathways even late in life.

When the brain’s temporal lobes are insufficiently activated by aural input, they shrink, raising the risk of dementia. Multiple studies have shown that people using hearing aids do not experience the cognitive decline otherwise associated with hearing loss.

Exercise augments your brain’s exposure to oxygen and nutrients. A study with 10,308 participants found that more than 2.5 hours a week of moderate to vigorous physical activity lowered dementia risk.

An analysis of 20 studies by the Lancet Commission indicated that a weight loss of 4.4 pounds among people with body mass indexes greater than 25 resulted in “significant improvement in attention and memory.”

A review of 45 studies indicated that light to moderate alcohol consumption reduced dementia risk. One of the most prevalent studies — in the United Kingdom with a 23-year follow-up — concluded that long-term abstinence and excessive drinking were associated with a 17 percent increase in dementia.

The commission’s review of 13 studies with up to 15 years of follow-up found associations between dementia and exposure to PM 2.5, NO2, and carbon monoxide. While air pollution requires en masse action, smoking remains an individual choice. The commission reported that, among 50,000 men 60 years and older, a cessation in smoking for more than four years substantially reduced dementia risk (tobacco being a triumvirate source of the aforementioned pollutants and affecting people through secondhand smoke).

Health conditions such as hypertension, high cholesterol, cardiovascular disease, diabetes, and depression have been linked to dementia. A National Institute on Aging study — reported in 2020 but covering a period with up to 26 years of follow-up on 6,000 participants — found that even gum disease contributes to the development of dementia.

All of this makes a powerful case for lifestyle adjustments and seeking treatment for medical issues.

As Alzheimer’s disease has become more prevalent, so have over-the-counter supplements for “brain health.” A 2021 AARP survey found that 21 percent of adults 50 and older took such products, and 12 percent of them did so to delay dementia. However, in 2019, the Global Council on Brain Health issued a paper that included this consensus statement: “Very few supplements have been carefully studied for their effect on brain health. For the handful that have been researched, several well-designed studies … found no benefit in people with normal nutrient levels.”

The council instead recommended that individuals choose foods known to support a healthy brain: “A plant-based diet that is rich in a variety of fruits and vegetables, particularly green leafy vegetables and berries, is associated with better brain health. Consumption of fish, as well as other types of seafood, seems to benefit cognitive function.”

The overall message from experts appears to be that taking care of one’s general health is a prime factor in what goes on inside our skulls.