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Researchers explore genetic roots, new diagnostic tools for early-onset dementia

Dementia is one of the most challenging medical and societal issues of our time, affecting memory, thinking and independence for millions of families worldwide. At UT Health San Antonio, researchers and clinicians are taking new steps to change that story through research, genetic insights and compassionate, integrated care.

At the heart of this mission is UT Health San Antonio’s new Center for Brain Health, which opened December 10, 2025, bringing together experts in neurology, genetics, neuropsychology and therapy under one roof. The center is the new home of the Department of Neurology and the Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases. The center’s mission is to better understand, diagnose and treat conditions like young-onset Alzheimer’s disease, which can strike decades earlier than typical onset of the disease.

Understanding a devastating diagnosis

“Dementia is a clinical syndrome in which a person develops progressive cognitive changes from their prior baseline,” said Jeremy Tanner, MD, PhD, assistant professor in the Department of Neurology at the Joe R. and Teresa Lozano Long School of Medicine and the Biggs Institute. “When these changes begin to affect daily function, that’s when mild cognitive impairment progresses to dementia.”

Jeremy Tanner, MD, PhD

While Alzheimer’s disease accounts for 60% to 80% of all dementia cases, early-onset Alzheimer’s, often defined as Alzheimer’s with symptoms appearing before age 65, is less common but can be more devastating. A 2021 report in JAMA Neurology estimated the prevalence of early-onset dementia to be 119 cases per 100,000 people, or about 3.9 million people ages 30 to 64 worldwide.

“When Alzheimer’s occurs earlier in life, people are often at the peak of their careers or raising young families,” Tanner said. “It’s something that can be missed or misdiagnosed, and by the time it’s recognized, the disease may already be advanced and progressing rapidly.”

For years, younger adults with cognitive symptoms were often told they had depression, anxiety or even post-traumatic stress disorder as the cause of severe cognitive impairment, Tanner said.

“I’ve seen patients misdiagnosed for years. Only recently are we beginning to identify early-onset Alzheimer’s disease and understand how important accurate diagnosis can be,” he said.

Dementia also carries a major economic impact, especially when it affects younger adults.

“If your brain isn’t healthy, you can’t engage fully in your work, with your family or your community,” Tanner said. “Optimizing brain health isn’t just a medical priority, it’s a social and economic one.”

New tools for early detection

Researchers now have more precise ways than ever before to detect Alzheimer’s disease earlier. Tanner’s research team is studying midlife testing with blood-based biomarkers, such as p-tau217, to see if these can detect disease activity up to 20 years before symptoms appear. These tests are available clinically and will soon be tested locally at the Biggs Institute, alongside advanced imaging such as amyloid and tau PET scans and cerebrospinal fluid testing.

“If a blood test is negative, that can be reassuring,” Tanner said. “If it’s positive, we follow up with confirmatory testing to ensure accuracy. The goal is to diagnose and begin treatment earlier in order to delay, or ultimately stop, the disease.”

While some forms of Alzheimer’s disease are linked to genetic mutations, called autosomal dominant Alzheimer’s, this represents less than 10% of early-onset cases. Most diagnoses of early-onset dementia are sporadic, meaning the cause is unknown. Tanner said this underscores the importance of continued research into lifestyle, environmental and lesser-known genetic risk factors for early-onset dementias.

“We only get one brain, and our goal is to help the brain function as well as it can for as long as it can. Research is how we get there,” he said.

The genetic perspective

Julia Castro, ScM, CGC

That’s where Julia Castro, ScM, CGC, a genetic counselor with the Biggs Institute, comes in. Her work helps families understand inherited risks and emerging genetic treatments for dementias including early-onset Alzheimer’s.

Gene therapy approaches vary depending on the problem. For example, if a gene is overactive or harmful, therapy may aim to neutralize it. If a gene is not functioning properly, therapy may introduce a healthy copy. Delivery methods, dosage and frequency all depend on the specific therapy and gene involved.

“While we don’t yet have FDA-approved gene therapies for Alzheimer’s, there are multiple clinical trials underway for various types of dementia, including frontotemporal,” Castro said. “Seeing these trials move forward is exciting because they’re paving the way for other dementias.”

Genetic testing can help families plan and make informed health decisions, but it’s not always easy news to deliver.

“It’s hard to tell someone their genes put them at higher risk when we don’t yet have a cure,” Castro said. “But knowledge is power, and with lifestyle modifications and early monitoring, we can make a meaningful difference.”

Beyond single-gene mutations, the latest genetic testing is exploring polygenic risk — the combined effect of multiple genes that each slightly increase risk.

“For families with a history of dementia, these medium- and low-risk genes that add up may explain more than the rare high-risk ones. Polygenic risk scores could allow us to monitor at-risk individuals earlier and guide lifestyle interventions proactively,” Castro said.

The role of lifestyle and prevention

Genetics is only part of the story when it comes to dementia risk. Lifestyle factors such as cardiovascular health, stress management, sleep, diet and social engagement play a significant role in brain health across the lifespan.

“Some genes increase dementia risk indirectly by affecting blood vessels and heart health,” Castro said. “That’s why what’s good for your heart is usually also good for your brain.”

In her counseling sessions, Castro helps patients make small, realistic changes.

“I tell people to pick an area or two where they’re already doing well and one or two in which they could improve. Then we make a game plan,” she said. “It’s important for people to have agency over their health.”

Personalized medicine and future therapies

Anti-amyloid drugs, which target abnormal amyloid protein buildup in the brain associated with Alzheimer’s disease, are offering new treatment possibilities for Alzheimer’s disease. But Castro notes that genetic factors can affect how patients respond.

“For example, people who carry the APOE e4 gene are more likely to develop Alzheimer’s, but they’re also at higher risk of side effects from these therapies. That’s why a personalized approach is so important,” she said.

The goal of the Center for Brain Health is to provide a place of progress and possibility.

“These families carry a legacy of dementia,” Castro said. “With advances in genetics, early detection, lifestyle interventions and new therapies, we can give them knowledge, tools and hope for a life less defined by inherited risk.”

A new model for care

The Center for Brain Health represents a major step forward for dementia care in South Texas. By bringing specialists together, the center aims to deliver truly comprehensive care.

“These diseases are complex, and it takes a multidisciplinary approach to provide the highest quality care,” Tanner said. “Having everything under one roof makes it easier for patients and families while allowing us to integrate multidisciplinary care with critical research.”

The center will offer state-of-the-art testing, including PET and MRI imaging, cerebrospinal fluid analysis and advanced biomarker testing. But its impact will go beyond diagnostics.

“Our goal is to integrate testing, care and research so that every clinical evaluation can also help us learn,” Tanner said. “Research is how we figure out what protects the brain and how to keep it healthy over a lifetime.”

Local footprint, global impact

South Texas has one of the highest rates of Alzheimer’s and dementia in the country, making the work of the Biggs Institute and the Center for Brain Health especially vital.

“We don’t know exactly why this is, but we’re determined to find out,” Tanner said. “By studying risk and protective factors here, we hope to generate insights that can be applied globally.”

 



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