Why boosting dopamine backfires in the Alzheimer's brain

Brandeis Stories

Why boosting dopamine backfires in the Alzheimer's brain

By David Levin
March 17, 2026

Dopamine is best known as the brain's reward chemical, a molecule that floods the nervous system when a person experiences something positive - yet also plays a central role in memory, helping the brain lock in new information and store it for the long term.

As the brain ages, dopamine-producing cells and receptors gradually disappear, but surviving cells can ramp up dopamine production to compensate. It's a kind of biological workaround - and, as Brandeis neuroscientist Anne Berry notes, plenty of research shows that older adults who maintain higher dopamine levels tend to have sharper memories.

That implication seemed hopeful: Maybe boosting dopamine could help protect aging brains, including those with Alzheimer's disease. A new study by Berry's lab, however, is putting a big caveat in that claim. In healthy older adults, they found, higher dopamine did indeed show better memory, as expected. But in adults with early signs of Alzheimer's disease, the relationship reversed: more dopamine seemed to make memory worse. The paper was published in February in the Journal of Neuroscience.

During the study, Berry and her colleagues used PET scans to track a group of older adults over time, tracking how much dopamine their brains created, and whether they contained the tau protein tangles and amyloid-beta protein "plaques", that are a hallmark of Alzheimer's. Her team also asked the study's participants to do a series of memory-intensive tasks in an fMRI machine to determine how well their memory recall worked.

"We think the extra dopamine is actually too much to handle for the system that consolidates memories," Berry says. "It's kind of like overdosing the system."

The stakes are practical. Drugs like Ritalin, which enhance dopamine levels in the brain, initially seemed promising as a cognitive aid for aging adults - yet Berry's work suggests that whether such drugs help or harm depends entirely on a patient's underlying brain health.

"It really informs precision medicine," she says. "You really need to be accounting for these other factors."