Walk down the supplement aisle in your local drugstore and you’ll find fish oil, ginkgo, vitamin E, and ginseng, all touted as memory boosters that can help you avoid cognitive decline.
You’ll also find melatonin, which is sold primarily in the United States as a sleep supplement.
It now looks like melatonin marketers might have to do a rethink.
In a new study, researchers found that melatonin and two of its metabolites help memories stick around in the brain and can shield mice, and potentially people, from cognitive decline.
The research was conducted by a team at Tokyo Medical and Dental University (TMDU) in Japan.
One of the easiest ways to test memory in mice is to rely on their natural tendency to examine unfamiliar objects.
Given a choice, they’ll spend more time checking out unfamiliar objects than familiar ones. The trick is that for something to be familiar, it has to be remembered.
Like in people, cognitive decline in mice manifests as poor memory, and when tested on this novel object recognition task, they behave as if both objects are new.
In the study, the team was curious about melatonin’s metabolites, the molecules that melatonin is broken down into after entering the body. They suspected that they might promote cognition.
To test their hypothesis, the researchers familiarized mice with objects and gave them doses of melatonin and the two metabolites 1 hour later. Then, they tested their memory the next day.
They found that memory improved after treatment and that one metabolite called AMK was the most effective.
All three metabolites accumulated in the hippocampal region of the brain, a region important for turning experiences into memories.
The researchers also found that long-term memory formation could not be enhanced after blocking melatonin from being converted into AMK in the brain.
The study shows that melatonin’s metabolite AMK can facilitate memory formation in all ages of mice.
Its effect on older mice is particularly encouraging and the researchers are hopeful that future studies will show similar effects in older people.
If this happens, AMK therapy could eventually be used to reduce the severity of Mild Cognitive Impairment and its potential conversion to Alzheimer’s disease.
One author of the study is Atsuhiko Hattori.
The study is published in the Journal of Pineal Research.
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