Alzheimer’s, the most common form of dementia, affects 6.2 million Americans 65 and older. It is one of the most feared diseases and also one of the most elusive in terms of treatment and cure.

On Monday, the Food and Drug Administration approved the first Alzheimer’s drug in nearly two decades, Biogen’s aducanumab, which will be sold under the brand name Aduhelm. The approval of the drug came after years of research and doubts over its effectiveness.

The approval is “a positive step in the right direction,” says Dr. Doraiswamy. It’s important, though, that clinicians and patients temper their expectations, he says, noting that not everyone with Alzheimer’s disease qualifies, and the benefits and effects are not “dramatic.”

Although the progressive brain disease has been difficult to fight, Dr. Doraiswamy is optimistic about advances in a variety of areas. Blood tests to detect Alzheimer’s at a doctor’s office are being developed and some home-based digital cognitive tools for tracking and possibly treating it have cleared the FDA. Researchers are finding ways to use sophisticated brain scans to detect Alzheimer’s-related proteins and have also identified how the seemingly unrelated condition of hearing loss is linked to higher risk of Alzheimer’s.

“I think it’s a hopeful time,” Dr. Doraiswamy says.

In this edited interview, he discusses promising tools for detecting Alzheimer’s, steps you can take to reduce risk, misconceptions about the disease and the impact of Covid-19 on dementia.

How do you tell the difference between memory issues in normal aging as opposed to Alzheimer’s and other dementias?

If you can’t remember what you forget, you have a problem. All of us forget stuff but it usually comes back a few hours later or when not so stressed or trying. Second is that it gets worse over time. Normal age-related memory loss usually doesn’t get substantially worse over time. Also with Alzheimer’s, cues rarely help. If you give other people a cue, they remember or give the right answer.

And while all of us have trouble learning new information and take a while to figure out a smart TV, Alzheimer’s patients find it impossible to use a new microwave or remote.

What are the most promising developments in detecting Alzheimer’s and treating mild memory problems?

Simple blood tests that appear to have reasonable diagnostic and predictive value. Instead of running a two-hour battery of tests or ordering complicated brain scans that cost thousands of dollars, a simple blood test can be done at a primary-care doctor’s office. They haven’t been approved by the FDA for routine clinical practice, but we are very close, and I expect within the next two years we will have several tests that can do that.

Also there are a number of digital-based cognitive tests. Some are free memory surveys and self-tests that anyone can take at home that provide a memory score, but require some expertise to interpret. One, the Self-Administered Gerocognitive Exam, includes simple math problems, a questionnaire and a drawing test. Some other digital-based cognitive tests, which have been cleared by the FDA, require a prescription and are used in memory assessments. One FDA-cleared test includes a series of brain games to assess five cognitive domains, including attention, working and episodic memory.

In the future, they could be coupled with digital therapeutics. So if you found that your memory, reaction time or concentration is weak, you would play specific sets of computerized cognitive games to strengthen those skills. These digital therapeutics have been approved for conditions such as ADHD and I see no reason why they can’t be available in the next year or so for treating mild memory problems.

What are some of the advances in brain research?

One big development is something called “Alzheimer’s in a Dish.” They’ve been able to form mini Alzheimer’s brains, with plaques and tangles, in a petri dish by using neurons from patients. That work was done at Massachusetts General Hospital and is a very big advance because you will be able to see if a drug works quickly. They can screen hundreds or thousands of drugs in months, compared to a more costly, time-consuming process using mice.

What are some preventive measures people can take on their own?

Diet. People on vegetarian or Mediterranean diets have cleaner brains in regards to Alzheimer’s pathology than those who eat a diet rich in saturated fat. A vegetarian diet has been associated with reduced amyloid pathology in the brain. Reducing vascular risks, controlling blood pressure, cholesterol, diabetes, weight—all of those have been shown to reduce your risk for developing dementia. Be mentally and socially active.

Hearing loss may be one of the biggest potentially reversible factors for Alzheimer’s risk. Studies have shown that if you have hearing loss for a long period, it causes shrinkage of brain regions that are very close to the memory centers. So hearing aids and regular hearing tests are very important.

What about sleep?

We know that sleep is when the brain boosts our immunity and archives our memories. We know that sleep is important for clearing toxic proteins from the brain. All those are crucial. So yes, it is important to get a good night’s rest for a healthy memory.

Much of the treatment and therapies seems to be targeted for those in the early stages. What about those in the middle or later stages?

We have medications on the market that treat symptoms of those in the middle stages, but we haven’t found anything to fix the damage in the brain once it has occurred. That is why there is so much urgency to develop preventive strategies.

What impact has the pandemic had on Alzheimer’s patients?

It prevented Alzheimer’s patients from getting proper care during the last 12-15 months. More people with Alzheimer’s died during the pandemic than with any other disease. There are some studies that have suggested there is an increased incidence of dementia among Covid survivors. We may end up with a new term, Covid dementia.

The research on Covid vaccine technology has really given a boost to the field in terms of rapid mobilization of resources and working with regulatory agencies. I’m hoping that will spill over into other fields, like ours.

What prevents people from getting tested?

Fear. Alzheimer’s is the most feared disease, even more so than cancer. People fear losing their independence, their identity and having to give up everything, from driving to managing their accounts. But a lot of patients who are diagnosed and in early stages can still drive and manage. It requires coordinated family planning around it to see what can and can’t be done.

Others think that it’s not worth getting evaluated because nothing can be done about it. But if you don’t get evaluated, you don’t know if it’s Alzheimer’s or something else. I had a patient who thought he had Alzheimer’s but it turned out to be a severe vitamin deficiency. We corrected it, and his cognition was back to normal.

It’s also important for people to get tested so they can make plans, including financial ones.

What do you do personally to keep your brain healthy?

I’m an academic. It helps that every day I’m doing challenging stuff from morning to night. I play tennis and exercise. I spend a lot of time socializing. I like chess and bridge. An occasional glass of wine 2-3 days a week. I’m a vegetarian, so I don’t have to worry about high saturated fat-related plaque build-up.

What do you expect to see in 10 years?

I think technology and brain science will be tightly integrated. I think we will have incredible tools to image the brain and detect early stages of disease pathology with a drop of blood.

We will probably have very sophisticated smartphone-based sensors and wearables that can predict the onset of Alzheimer’s.

I hope we will have a vaccine to prevent Alzheimer’s in 10 years, but it remains to be seen.

Write to Clare Ansberry at clare.ansberry@wsj.com