Could Low Serotonin Levels Drive Alzheimer’s Disease?

Past studies have noted that people with Alzheimer’s disease have less serotonin in their brains than other adults. The chemical monitors and regulates appetite, mood, sexual function, sleep and more in the body. Recent studies now suggest that low serotonin levels may be more than a side effect of Alzheimer’s – it may actually drive the disease.Could Low Serotonin Levels Drive Alzheimer's Disease?

Learn more about the most recent study and how it may affect Alzheimer’s drug research.

The Relationship Between Alzheimer’s and Serotonin Levels

While the cause of Alzheimer’s is still unknown, researchers are dedicated to understanding the pathology of the disease and how genetic, molecular and neurological components contribute to its development and progression. Past studies have shown that people with Alzheimer’s have less serotonin in their brains a neurotransmitter which regulates appetite, mood, sleep and sexual function. Other past studies have shown that a decrease in monoaminergic neurons (the neurons that regulate serotonin and other neurotransmitters) are linked to an increase in beta-amyloid plaque in the brain. Researchers are not sure if the lack of serotonin and its regulators are a cause or effect of Alzheimer’s.

Now, a new study from the Johns Hopkins University School of Medicine in Baltimore confirms that serotonin levels play a crucial role in the pathology of Alzheimer’s, even suggesting the chemical may drive the disease and not just be a side effect of living with it.

The study used positron emission tomography (PET) scans to evaluate the brains of 56 participants. Researchers divided the participants into two groups one group with mild cognitive impairment (MCI) and one group with healthy adults (the control group). Using radioactive carbon, researchers were able to trace the activity of serotonin and its transmitters during the scans, finding that those with MCI had 38% less than their healthy counterparts.

Furthermore, researchers compared the results of cognitive testing with PET scan results and found that those with MCI performed 37% worse in verbal memory and had 18% less serotonin than the control group.

Targeting Serotonin Transmitters

Gwenn Smith, Ph.D., first and corresponding author of the study, and a professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine says:

“Now that we have more evidence that serotonin is a chemical that appears [to be] 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.”

While more research needs to be done to understand how serotonin behaves in a brain with Alzheimer’s, this study suggests that serotonin levels may be a therapeutic target for future drug trials.

Were you surprised to hear a loss of serotonin could affect Alzheimer’s? We’d like to hear your thoughts on the study in the comments below.

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  • Margaret Atienza

    My mother’s alzheimers is moderately advanced — almost all the time suffers from anxiety, very agitated, obsessive-compulsive moods. Recently her neurolgist prescribed seroquel in order to control these symptons. However I read that seroquel block serotonin, isn’t this contradictory to studies about low level of serotonin being or could be the cause of alzheimer’s? It will be most appreciated if anyone can share their knowledge on this.

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