Scans show lower brain serotonin levels linked to dementia

Roughly 5.5 million people in the United States have Alzheimer's disease related dementia.

By Amy Wallace

Aug. 14 (UPI) -- Researchers at Johns Hopkins School of Medicine found that lower levels of serotonin transporter in the brain are linked to dementia.

Serotonin transporter is the brain chemical responsible for appetite, sleep and mood. Previous research has shown that people with Alzheimer's disease and other severe cognitive decline have severe loss of serotonin neurons.


Researchers examined brain scans of patients with early signs of memory decline and found that lower serotonin transporters may be the driving force of dementia, not a byproduct.

The study, published in the September issue of Neurobiology of Disease, found that targeting the loss of serotonin or using a substitute neurotransmitter may slow or halt the progression of Alzheimer's disease and other dementias.

"Now that we have more evidence that serotonin is a chemical that appears affected early in cognitive decline, we suspect that increasing serotonin function in the brain could prevent memory loss from getting worse and slow disease progression," Dr. Gwenn Smith, a professor of psychiatry and behavioral sciences and director of geriatric psychiatry and neuropsychiatry at the Johns Hopkins University School of Medicine, said in a press release.


Researchers conducted MRI and PET scans of 28 participants with mild cognitive impairment, comparing the scans to 28 healthy controls. The study participants were an average of 66 years old and 45 percent female.

During the PET scans, participants were given a chemical similar to an antidepressant labeled with a radioactive carbon, which binds to the serotonin transporter and is detected through radioactivity.

Participants also took learning and memory tests, including the California Verbal Learning Test and the Brief Visuospatial Memory Test.

Researchers found when they compared the brain imaging tests to the memory tests, lower serotonin transporters were associated with lower scores on the tests.

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