A new study has identified a genetic variant that increases the risk of a damaging brain pathology found in many Alzheimer's patients, potentially explaining why some people experience faster cognitive decline than others. The discovery could eventually lead to more personalized approaches for diagnosing and treating Alzheimer's disease.

What Is TDP-43 and Why Does It Matter in Alzheimer's?

Alzheimer's disease is typically defined by the buildup of amyloid plaques and tau tangles in the brain. However, scientists increasingly recognize that many patients also develop additional pathologies that influence how the disease progresses. One of the most important is TDP-43, a protein that accumulates abnormally in nerve cells.

TDP-43 pathology is associated with faster cognitive decline, greater brain atrophy, and poorer outcomes in Alzheimer's disease. Researchers found that TDP-43 is present in 40% of Alzheimer's cases, and its presence has been linked to increased memory loss and lower cognitive performance. In fact, previous research has suggested that the absence of TDP-43 pathology may be one of the strongest predictors of cognitive resilience in older adults.

How Did Researchers Identify This Genetic Link?

Scientists at the University of Miami Miller School of Medicine conducted a study published in Alzheimer's & Dementia, examining postmortem brain tissue from 2,604 individuals with neuropathologically confirmed Alzheimer's disease. The research team, led by Leonard Petrucelli, Ph.D., and Mercedes Prudencio, Ph.D., evaluated the presence of various brain pathologies while performing detailed genetic analyses.

The researchers discovered that a specific variant in the TMEM106B gene, known as rs3173615, was significantly more common in Alzheimer's patients who had TDP-43 pathology. Carriers of this variant had increased odds of developing TDP-43 pathology even after accounting for age, sex, disease severity, and other genetic risk factors.

Notably, TMEM106B did not increase the likelihood of developing other co-pathologies like Lewy body pathology or vascular lesions. This finding suggests the gene acts through a specific biological pathway rather than broadly increasing vulnerability to all forms of brain pathology.

What Makes This Discovery Significant for Patients?

The study also examined different forms of TDP-43 pathology and found that TMEM106B was strongly associated with TDP-43 subtype alpha, a form characterized by more widespread distribution of abnormal protein inclusions throughout the brain. Patients carrying two copies of the risk variant were particularly likely to develop this subtype.

Although the exact mechanism remains under investigation, the findings point toward disruptions in lysosomal pathways, the cellular systems responsible for processing and clearing proteins. Previous studies have shown that TMEM106B variants can promote the formation of TMEM106B fibrils and alter protein-clearance mechanisms, which may create conditions that facilitate TDP-43 aggregation.

The findings do not immediately change patient care, but they contribute to a growing understanding that Alzheimer's disease is biologically diverse. Rather than a single disorder defined solely by amyloid and tau, Alzheimer's increasingly appears to be a collection of overlapping disease processes influenced by distinct genetic factors.

Can Blood Tests Detect Memory Risk Years in Advance?

In related research, scientists at the Miller School also discovered that a blood biomarker may reveal subtle signs of future memory vulnerability long before memory problems can be detected through standard cognitive testing. In a study of 1,170 older adults, researchers found that higher levels of phosphorylated tau 181 (p-tau181), a blood biomarker associated with Alzheimer's-related brain changes, were linked to poorer memory performance six years later, even when memory appeared normal at the time blood samples were collected.

The study participants completed extensive cognitive evaluations in 2016 and again in 2022. At the start of the study, 931 participants were cognitively normal, 206 had mild cognitive impairment, and 33 had dementia.

"p-tau181 was not associated with memory at the initial assessment, but it was associated with memory performance six years later. That suggests these blood markers may provide information about future cognitive vulnerability that is not apparent from cognition measured at the same point in time," explained Deirdre O'Shea, Ph.D., assistant professor of cognitive neurology at the Miller School.

Deirdre O'Shea, Ph.D., Assistant Professor of Cognitive Neurology, University of Miami Miller School of Medicine

The researchers examined four emerging blood markers associated with Alzheimer's disease and neurodegeneration:

• Phosphorylated tau 181 (p-tau181): A biomarker increasingly viewed as a promising indicator of Alzheimer's-related brain changes, particularly linked to future memory decline.
• Glial fibrillary acidic protein (GFAP): A marker associated with brain inflammation and linked to multiple cognitive domains including memory and executive function.
• Neurofilament light chain (NfL): A marker of neuronal damage that showed broad associations with memory, executive function, and overall cognition at baseline.
• Amyloid beta 42/40: A ratio of proteins associated with Alzheimer's pathology, though its association with cognitive outcomes weakened over the six-year period.

The analysis revealed that different biomarkers were associated with different aspects of cognition. Six years later, p-tau181 remained independently associated with lower memory and global cognition, while GFAP was linked to poorer memory, executive function, and overall cognition.

How Can People Protect Their Brain Health Before Symptoms Appear?

Research increasingly suggests that Alzheimer's-related changes can begin decades before symptoms appear, sometimes as early as a person's 30s. The good news is that lifestyle factors may be modifiable before symptoms begin.

Experts emphasize that preserving memory begins before cognitive problems are noticeable. Here are evidence-based approaches to support long-term brain health:

• Regular Physical Activity: Exercise can improve cognitive reserve, support the growth of new neurons in the hippocampus (a brain region critical for memory), increase Brain-Derived Neurotrophic Factor (a protein that supports brain health), reduce inflammation, and improve blood flow and oxygen delivery to the brain. Resistance training may be especially important, as people with greater leg strength and muscle power consistently show larger brain volume and better-preserved cognitive function later in life.
• Quality Sleep: Even one night of poor sleep may increase amyloid-beta accumulation, a hallmark protein associated with Alzheimer's disease. Over time, chronic sleep deprivation can contribute to lost neuron connections, shrinking gray matter volume, slower processing speed, and memory decline.
• Consistent Movement Throughout the Day: For desk workers, simple habits like 10 air squats every hour can counter prolonged sitting and improve circulation, glucose regulation, muscle activation, and neurological stimulation.
• Cognitive Stimulation: Activities such as reading, handwriting, and meaningful conversation help strengthen the neural connections that support memory, focus, and processing speed.

The brain's roughly 87 billion neurons form connections for memory, movement, focus, processing speed, and emotional regulation. Those connections strengthen with consistent stimulation, especially through physical activity.

While these findings cannot predict whether a specific individual will develop Alzheimer's disease, mild cognitive impairment, or dementia, they suggest that subtle biological changes detectable in a blood sample may precede measurable memory changes by years. For researchers seeking earlier ways to understand Alzheimer's disease progression, that window could provide valuable insight into the earliest stages of cognitive vulnerability.

The convergence of genetic discoveries and blood biomarker research points toward a future where doctors may be able to identify individuals at higher risk for cognitive decline and tailor interventions accordingly, potentially slowing or preventing the progression of Alzheimer's disease before symptoms become apparent.