Can’t remember that movie star’s name? You’re not alone. Memory declines as people get older. Here’s the latest on studies testing diet, drugs, or other measures to slow that cognitive decline...and, ideally, ward off dementia.

1. New drugs slow memory loss...but very modestly

In January, the FDA approved lecanemab (sold as Leqembi) to treat people with early Alzheimer’s disease. The agency is expected to approve donanemab, a similar drug, by late 2023. 

How do they work?

“They’re laboratory-developed antibodies that bind to a protein called beta-amyloid and enable its removal from the brain,” explains David Knopman, professor of neurology at the Mayo Clinic.

Amyloid plaques and tangles of abnormal tau proteins are the hallmarks  of Alzheimer’s.

“It’s tau, not amyloid, that’s linked to cognitive decline in observational studies,” says Knopman.

“Removing amyloid is believed to lessen tau accumulation, and that, in turn, seems to be linked to less cognitive decline.”

Indeed, in company-funded trials, people with early Alzheimer’s who were given lecanemab or donanemab intravenously for 18 months had better scores on dementia rating scales than those who got a placebo.

But participants in both groups got worse during the trials, and the drugs’ benefit was likely imperceptible to patients or their family members.

“When a drug slows the worsening of a disease, it’s impossible for anybody to detect, because no one knows where the patient would have been 18 months later if they hadn’t been treated,” notes Knopman.

Would the gulf between the drug and placebo takers have widened over time?

“We only have data out to 18 months,” says Knopman. “Whether the benefit increases, stays basically the same, or attenuates is unknown.”

And apart from the inconvenience of getting IV infusions every few weeks, neither drug was risk-free.

“The main set of adverse effects are amyloid-related imaging abnormalities, or ARIA,” explains Knopman. They’re caused by edema (swelling) or small hemorrhages in the brain.

“Roughly one person in five taking lecanemab, and maybe one person in three getting donanemab, would experience ARIA,” he says.

ARIA were more common in people with APOE4 gene variants, which increase the risk of Alzheimer’s.

“The majority of ARIA caused no symptoms,” notes Knopman. (They were detected by the trial’s periodic MRI scans.) “But there were occasional serious consequences.”

For example, at least two patients who got lecanemab died of brain hemorrhages after the trial ended. One had two copies of the APOE4 gene and doctors gave her a clot-busting drug, t-PA (tissue plasminogen activator), after she had a stroke. She immediately experienced multiple brain hemorrhages.

“I would strongly discourage individuals with two copies of APOE4 from receiving this therapy,” cautions Knopman, “one, because of the possible lack of benefit and two, because of the high rate of ARIA.”

In fact, only a fraction of people with memory loss are good candidates for thedrugs, says Knopman.

“First, they were only tested and approved for people in a very narrow range of mild cognitive impairment and mild dementia.”

“Second, patients should be in good health otherwise, because we’re talking about a long-term benefit. They shouldn’t have heart disease, other neurologic diseases, or cancer.”

“Third, they have to be able to undergo an MRI to look for ARIA. And fourth, they have to have elevated brain amyloid measured either by a spinal fluid test or a PET scan.”

“In my view,” adds Knopman, “they should also not be on an anticoagulant because of the excessive risk of bleeding.”

“Those exclusions take out a large fraction of people who might think they would qualify.”

Yet doctors can prescribe lecanemab without testing for APOE4 or ARIA.

“Medicare requires a statement by the treating physician that they had measured amyloid,” says Knopman.

“But any doctor can prescribe any drug, which makes me anxious.”

“I am convinced that lecanemab treatment requires a multidisciplinary team that has an expert neuroradiologist to check for ARIA and other team members who know about the drug, genetics, neuropsychology, and the diagnosis of mild cognitive impairment and dementia.”

Any doctor can also prescribe aducanumab (Aduhelm), but Medicare will only pay for it for people who participated in clinical trials. Trials found no evidence that it curbs memory loss.

In contrast, lecanemab and donanemab are a step forward.

“These drugs represent a considerable advance by showing that amyloid removal can move the needle on dementia rating scales,” says Knopman. “But from a practical point of view, the jury is still out as to how much they will help patients.”

2. A multivitamin may slow normal memory decline

Can’t think of a word, but five minutes later, it pops into your head?

“That’s usually a normal part of aging,” says Adam Brickman, professor of neuropsychology at Columbia University.

“Just like our vision, hair, and skin change as we grow older, our memory can also change—particularly when it comes to learning new information over short periods of time.”

That’s not necessarily a sign of early Alzheimer’s, with its distinctive plaques and tangles. “But the changes can be frustrating,” notes Brickman.

He led the COSMOS-Web trial, which randomly assigned 3,562 older people to take a daily multivitamin (Centrum Silver) or a placebo.

“After one year, memory improved significantly more in people who were taking the multivitamin than in people who were taking the placebo,” says Brickman. “And on average, that difference was sustained over the three-year study.”

But the multivitamin was far from a panacea. “If you look at the points on the memory test, the difference looks very small,” says Brickman.

The vitamin takers could recall an average of 7.10 out of 20 words when the study started and 7.81 words a year later. The placebo takers went from 7.21 to 7.65 words.

“You’re not going to wake up and think, ‘Oh, my memory is so much clearer than it was before I started taking vitamins,’” says Brickman.

“But we estimated that the impact of the multivitamin was equivalent to about three years of cognitive aging.”

What’s more, the results agree with those from COSMOS-Mind, another trial that used Centrum Silver.

“The way we tested memory was different in the two studies, yet the effects were remarkably similar,” notes Brickman. “That kind of replication helped convince me, as a skeptic, that what we’re seeing is valid and meaningful.”

In both trials, the multivitamin had a bigger impact in people with cardiovascular problems. Why?

“The absorption of vitamins or minerals from foods might be worse in people with cardiovascular disease,” suggests Brickman.

How might a multivitamin help?

“Given the cognitive tests where we saw improved outcomes, I’d speculate that the effects are due to changes in a part of the brain called the hippocampus.”

“But what’s happening at the cellular or molecular level is hard to infer from these trials.”

Brickman’s takeaway: “If people are worried that their memory is affecting their day-to-day living, vitamins aren’t going to improve that, especially if there’s an underlying neurodegenerative disease like Alzheimer’s.”

“But in the course of normal cognitive aging, there’s emerging evidence now that multivitamins may potentially help us as we grow older.”

3. The MIND diet comes up empty

The disappointing news hit in July.

In a trial of roughly 600 older adults with a family history of dementia, a suboptimal diet, and excess weight, those who were randomly assigned to eat a MIND diet for three years scored no better on cognitive tests than those assigned to eat their usual diet.

The MIND diet is a mix of a healthy Mediterranean diet and a DASH (Dietary Approaches to Stop Hypertension) diet, with a few tweaks.

It curbs saturated fat and added sugars by limiting red and processed meats, full-fat cheese, butter, margarine, pastries, sweets, and fried foods. And it’s rich in blueberries, nuts, and extra-virgin olive oil—all provided by the trial—along with leafy greens and fish. Why that diet?

“In studies that follow people for years, those who eat Mediterranean or DASH diets have less decline in cognitive function with age,” says co-author Frank Sacks, professor emeritus of cardiovascular disease prevention at the Harvard T.H. Chan School of Public Health. (Of course, something else about those people may have helped keep them sharp.)

Both groups were also told to eat 250 fewer calories per day.

“We wanted to do something for the control group and keep them engaged,” explains Sacks. “We also wanted to make sure that the MIND group didn’t gain weight, because we were giving them high-calorie foods like olive oil and nuts.”

After three years, cognitive test scores improved, but no more in the MIND group than in the control group. (Both groups lost about 11 pounds.)

What could explain those findings?

“The simplest explanation is that diet doesn’t slow or speed up cognitive aging,” says Sacks.
Or maybe the study was too short.

“With coronary heart disease or stroke trials, three years is quite sufficient to test a statin,” says Sacks. “With cognitive decline, three years may not be anywhere near enough.”

A third possibility: “The training effect is so powerful that there’s nothing further you can do with diet,” suggests Sacks.

“Those tests had difficult questions and puzzles. The first time you take one, you don’t know what’s coming, but you get better with practice.”

Would he still recommend a DASH or Mediterranean diet? You betcha.

“You get lower blood pressure, lower LDL cholesterol, less inflammation, preserved cardiac function. Those benefits are well established by many clinical trials.”

“But should you expect to be able to think better when you’re 75? That needs more research.”

DASH Diet

A DASH diet keeps a lid on blood pressure, which can help protect the brain’s blood vessels. Here’s a 2,100-calorie version. A Mediterranean diet is similar, but you’d largely use the “Wild Card” for extra olive oil. (Note: Some servings are quite small.)

4. It’s unclear if hearing aids help protect memory

Hearing loss is a risk factor for dementia, according to a 2020 Lancet Commission report. (Among the others: air pollution, depression, diabetes, excessive alcohol consumption, high blood pressure, less education, low social contact, obesity, physical inactivity, smoking, and traumatic brain injury.)

“In a number of studies, hearing loss in older adults was associated with an increased risk of dementia,” says Jennifer Deal, associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.

And there’s reason to think that poor hearing could harm memory.

“Hearing loss can lead to social isolation,” notes Deal. “It can also increase cognitive load—that’s the extra processing effort that the brain needs to decode a degraded auditory signal. So you can’t devote as much energy to forming memory.”

Hearing loss may even affect brain structure. “In one study, people with hearing loss had faster rates of brain shrinkage, particularly in areas of the brain that are important for speech processing, sound integration, and memory,” says Deal.

That evidence led researchers to launch the ACHIEVE trial.

“We enrolled 977 individuals between the ages of 70 and 84 with untreated mild-to-moderate hearing loss,” explains Deal.

They were randomly assigned to get a hearing intervention (hearing aids, devices to stream sound from a phone or TV into hearing aids, etc.) or to a control group that got personal advice from a health educator.

The results: “The rate of cognitive decline in the two groups was essentially the same after three years,” says Deal.

But that wasn’t the case when the researchers looked separately at the volunteers they had recruited for ACHIEVE (75 percent of the total) versus the ACHIEVE volunteers who had also participated in the Atherosclerosis Risk in Communities (ARIC) study for some 30 years.

“Among the ARIC participants, the hearing intervention was associated with a 48 percent reduction in global cognitive decline compared to the control intervention,” says Deal.

One possible reason: The ARIC group was at greater risk.

“They were older and had a lower level of educational attainment,” Deal explains. “They also had lower cognitive scores when the trial began, and they had faster rates of cognitive decline over the three years.”

Whether hearing aids help people at greater risk needs confirmation. Until then, remember that hearing aids are now easier to get.

And if you get them, be patient. “Give your brain time to understand the new input that it’s getting,” says Deal.

5. If it’s good for the heart, it’s good for the brain

The plaques and tangles of Alzheimer’s aren’t the only cause of memory loss in older people.

“Cerebrovascular disease—that is, disease in the blood vessels of the brain—often overlaps with Alzheimer’s disease,” notes the Mayo Clinic’s David Knopman.

“It’s a common contributor to cognitive impairment in later life, even if it’s not the marquee player.”

For example, in people with no history of a stroke, an MRI can reveal tiny “lacunar infarcts”—cavities created when clogged blood vessels fail to deliver oxygen to brain cells.

“And abnormal white matter hyperintensity lesions increase steadily after age 65,” says Knopman.

The good news: You can help protect your brain’s blood vessels.

“Preventing or treating risk factors like diabetes, high blood pressure, smoking, obesity, and lack of exercise in young adulthood and mid-life could reduce the overall burden of dementia in later life,” says Knopman.”

To protect your brain 

Here’s what may preserve your memory, based on numerous studies.

• Aim for a systolic blood pressure of 120 or lower.
• Keep a lid on blood sugar with diet or medication.
• Don’t smoke.
• Eat a DASH diet to keep a lid on blood pressure.
• Lose (or don’t gain) excess weight.
• Exercise for at least 150 minutes a week.
• Stay mentally and socially active.
• Get 7 to 9 hours of sleep.
• Consider a multivitamin. (At a minimum, you’ll get vitamins B-12 & D that you can’t get from food.)
• Don’t bother taking DHA, ginkgo, Prevagen, or vinpocetine.