Alzheimer’s disease and dementia affect millions of older adults, and while treatments are advancing quickly, many people still have questions about prevention and daily life. Brain health isn’t just about medicine; it’s also about lifestyle choices like exercise, sleep, and diet, which can make a real difference in how we age.

Leading efforts in both research and patient care is Dr. Jessica Rexach, physician-scientist and specialist in neurogenetics at UCLA Health. Her work brings together cutting-edge research with hands-on care for patients living with memory loss, movement disorders, and other age-related conditions.

I sat down with Dr. Rexach to talk about the latest breakthroughs in Alzheimer’s research, why exercise is so powerful for the brain, and how everyday habits can help keep us sharp and resilient as we grow older.

Tell us about your background.

I’m a physician-scientist. I did my PhD at Caltech, and then a postdoctoral fellowship in functional genomics and systems biology at UCLA. Now I both see patients and run a research lab using human data and stem cell models to study disease pathways. I chose clinical areas that synergized with my research, which led me to genetics. But targeting dementia was my goal since I was a teenager, after watching my grandfather go through Alzheimer’s disease. It felt profoundly unfair and something worth fighting against. His vulnerability inspired me to focus on this field. Over time, opportunities kept aligning, and now we’re at the precipice of revolutionary progress in Alzheimer’s and dementia.

That’s amazing. What kind of progress is being made in understanding Alzheimer’s?

For a long time, we didn’t know what caused Alzheimer’s disease. Genetic profiling helped us identify modifier genes, but we didn’t understand mechanisms. Recent technology allows us to measure how these genes affect people in real time. We’re now crystallizing our understanding of what’s going wrong. With that precision, we can use powerful tools—cell therapies, immune therapies, gene editing, and nucleic acid–based treatments. We already have the first approved gene therapy for a degenerative disease. The tools exist. Now it’s about applying them precisely.

How does precision medicine work with lifestyle changes like exercise?

Working with individuals is always precision. Medicine is catching up with more tools like pharmacogenetics, where we profile enzymes that metabolize drugs. That helps us predict which drugs will work best with fewer side effects. But lifestyle choices remain the foundation. The body is constantly repairing itself. Healthy habits keep the balance of injury and repair tilted toward resilience. That’s why people who exercise and eat well often manifest disease later, less severely, and recover better. Lifestyle doesn’t prevent everything, but it improves resilience and outcomes.

I see patients in two different clinical practices at UCLA Health: the UCLA Memory Clinic, or Alzheimer’s/dementia clinic, and the UCLA Neurogenetics Clinic. I actually see more patients in neurogenetics, including movement disorders and cognitive decline. In both cases, I spend about half my time counseling patients and encouraging them to exercise.

Why is exercise important for brain health as we age?

The reason for this is the neuroprotective aspects of exercise against aging and disease. Animal models show that if they exercise more, they age better. The recent Alzheimer’s-related POINTER study demonstrating the benefits of a healthy lifestyle, including regular exercise. It highlighted the recommended threshold of exercise for patients with cognitive impairment and Alzheimer’s. I tell patients with mild cognitive impairment that even 10–15 minutes of exercise in the morning can improve focus and memory that day.

Another important piece is modalities. When patients have deficits in one part of the brain and other parts are healthy, it’s important to use multiple modalities of brain function. A classic example is Parkinson’s patients moving to music. Dance classes help because auditory cues improve movement. The same applies to degenerative disorders. Brains don’t degenerate uniformly, so utilizing preserved areas is important. Multimodal interventions can be powerful. For patients with cerebellar ataxia and other movement disorders, data shows the most important factor in their function is exercise. We also emphasize core work to prevent falls.

When patients have balance problems, strengthening spinal muscles reduces fall risk for the next 48 hours by improving reflexes and tone. For older adults with serious diseases, exercise isn’t about looking perfect. It’s about achievable goals. Weight loss can be difficult due to slower metabolism with age, so I emphasize strengthening core and joint muscles for immediate impact, and also talk about the neurohormonal benefits for cognitive decline. These short-term goals help patients. Most of my patients don’t have cures, so we spend a lot of time on this.

My clinical practice keeps me grounded and inspired. My goal is to provide treatments, information, and resources to patients, most of whom are really good people. That’s the joy of being a doctor.

How does exercise boost focus?

We all know how much better we feel and focus after exercise. Sometimes you don’t need a $10 million placebo-controlled trial. I pull a lot from personal experience. Patients tell me they benefit too. Physiologically, one of the drugs we use for Alzheimer’s boosts cholinergic tone in the brain, and exercise does something similar. I’m extrapolating from exercise physiology to brain chemistry. Alzheimer’s treatments like Lecanemab and anti-amyloids are great, but I also coach on exercise and sleep, which are important for brain “cleaning.” Exercise clears lactate and toxins from the brain into circulation for removal. These observations in the labs help explain why people feel better, but we can easily see and feel the improvements we gain from regular exercise.

I base this more on human physiology than disease physiology. Alzheimer’s drugs like donepezil boost neurotransmitter function, helping alertness and memory retrieval. Exercise mirrors some of those changes naturally. I want to achieve similar benefits through exercise as a complementary modality. We know for sure that it won’t hurt the brain, and there is a lot to guide people on safe exercise when they need extra guidance because of another medical condition that might require adaptive exercise.

When we exercise, what happens in our body and brain with hormones?

During exercise, adrenaline and dopamine increase. Mood improves, and focus centers in the brain are activated. It’s like the fight-or-flight response, but in exercise you can also get parasympathetic activity, the rest-and-digest system. This happens when you include more mild-moderate intensity with factors that give us joy, like community, music or beautiful spaces, or exercises with calming breath like Tai Chi or certain types of yoga. So you get both alertness and calm, which drugs can’t replicate. That’s why exercising with external stimuli (like music, nature, and social interaction) enhances benefits. If you exercise in isolation with no stimulation, you lose some of that calming effect.

Research also supports this. For example, studies on “awe walks” show patients with anxiety feel calmer and more focused when as they walk they engage with their environment to find and describe things that inspire “awe”. Exercise engages the body and external world, raises epinephrine for focus, while it can also calm through parasympathetic input. It’s a powerful combination.Gyms and exercise classes provide community, taking you outside your head. Because modern life is sedentary, we need structured ways to recreate the natural activity and social connection our ancestors had. Physiology supports why these things make us healthier as we age.

What challenges do people face when trying to make changes, like exercising more?

I do a lot of one-on-one coaching, but success is limited because patients lack resources. Many face financial, mobility, or time barriers. Insurance rarely covers exercise programs, though it should. Many want help but don’t want to burden their families.  Programs like yours that partner with insurance are impressive. We need more community investment to make exercise accessible, especially for older adults.

You may be eligible for Bold’s online exercise classes at no cost through your health plan. Check your eligibility and get moving to experience the benefits of movement for your brain and body today.