Autism and Alzheimer's Share Surprising Biological Links That Could Transform Treatment

Genetic Discoveries Challenge Medical Assumptions

For decades, autism and Alzheimer's disease have been viewed as completely separate conditions — one affecting brain development in children, the other causing decline in older adults. But recent research is revealing startling biological connections that could revolutionize how we understand and treat both conditions.

A 2025 review published in the International Journal of Molecular Sciences identified at least 148 genes in common, many of them tied to the same fundamental processes that shape and sustain the brain over time. These shared genes, including MECP2, ADNP, and GRIN2B, are deeply involved in how brain cells connect, signal and adapt over time.

Joseph Buxbaum, a professor at Mount Sinai's Icahn School of Medicine, initially dismissed the connection. "I didn't want to believe it," he said, noting how one condition affects early brain development while the other drives decline in old age. But the evidence kept mounting.

Brain Cleanup Systems Show Similar Problems

Scientists have discovered that both conditions may involve problems with the brain's waste disposal system. Researchers described possible commonalities in MRI findings between autism and Alzheimer's, particularly involving the glymphatic system — a brain-wide network that helps clear metabolic waste, especially during sleep.

Obstruction of the CSF's normal nasal lymphatic drainage results in abnormal processing of the waste proteins tau and amyloid in the brain in both of these disease states. This discovery is particularly intriguing because the brain's cleanup system is closely linked to smell — and smell problems occur in both conditions.

In Alzheimer's, people often lose their sense of smell before memory problems begin — and although smell issues have been reported in autism, they have largely been overlooked. This connection could provide early warning signs and new treatment targets.

Research Gaps Create Opportunities

The timing of this research is crucial. Autism has long been treated almost exclusively as a childhood condition, with little attention paid to how it evolves with age. An analysis published last year found that just a tiny fraction of the more than 40,000 autism papers published between 1980 and 2021 included people over 50.

This research gap exists partly because autism was first formally recognized as a distinct diagnosis in 1980, and went largely unidentified in older generations. Now, as the first large diagnosed cohort reaches middle age, scientists are finally studying how autism affects people throughout their lives.

Treatment Breakthroughs on the Horizon

Both conditions remain mysterious and difficult to treat, and studying them together may open new paths for intervention. The shared genetic and biological pathways suggest that treatments developed for one condition might benefit the other.

Researchers are particularly excited about the therapeutic possibilities. The recognition of overlapping pathophysiologic and genetic features between the two disease states not only furthers understanding of these complex conditions, but could also pave the way for novel therapeutic avenues.

While much of the research remains preliminary, the implications are profound. Understanding how the brain develops problems early in life might reveal why it breaks down later. This paradigm shift could lead to earlier interventions, better treatments, and ultimately hope for millions of families affected by these challenging conditions.