Scientists may soon be able to reverse age-related memory decline in seniors.
It is a known fact that a person's memory tends to decline with age. Between 15 and 20 percent of people over the age of 65 years have mild cognitive impairment (MCI) — a condition that is no cause for concern on its own but that raises the risk of Alzheimer's disease.
Misplacing things once in a while or having trouble finding one's words can be a natural part of the aging process. However, researchers may now have found a way to reverse this form of age-related memory loss.
Joel Voss, who is an associate professor at the Northwestern University Feinberg School of Medicine in Chicago, IL, is the lead investigator of the new study.
Voss and his team used a noninvasive form of brain stimulation called transcranial magnetic stimulation (TMS) to improve memory in older adults. The researchers published their findings in the journal Neurology.
Using TMS to target the hippocampus
TMS works by applying magnetic fields to specific brain areas, thus affecting the central nervous system. The technique operates completely outside of the body, which means that it is noninvasive.
In this case, Voss and team applied TMS to the participants' hippocampus — a brain area that shrinks with age and that previous research has linked with age-related memory loss.
The hippocampus is "the part of the brain that links two unrelated things together into a memory, like the place you left your keys or your new neighbor's name," explains the lead researcher. "Older adults often complain about having trouble with this."
In the current study, Voss and team recruited 16 adults aged between 64 and 80 years and used functional MRI to locate the hippocampus in each participant.
As the hippocampus is too deep in the brain for the magnetic fields to reach it, the researchers targeted a superficial brain area in the parietal lobe that connects with the hippocampus instead. Doing this made it possible to use TMS to affect the hippocampus indirectly.
"We stimulated where brain activity is synchronized to the hippocampus, suggesting that these regions talk to each other," explains Aneesha Nilakantan, the study's first author.
The researchers applied high-frequency magnetic stimulation to this brain area for 20 minutes each day for 5 consecutive days. Before and after the intervention, the researchers tested each participant's memory using standard memory tests.
The tests involved remembering random associations between a variety of things, such as objects, places, or words. Usually, young adults get 55 percent of these associations correct while older adults score below 40 percent.
Memory restored to young adult level
After receiving the TMS intervention, the seniors in the study scored the same as young adults typically would in the standardized memory tests.
Voss and team also carried out a sham intervention, which did not yield the same results.
"Older people's memory got better up to the level that we could no longer tell them apart from younger people. They got substantially better."
The lead researcher comments on the uniqueness of the study, saying, "There is no previous evidence that the specific memory impairments and brain dysfunction seen in older adults can be rescued using brain stimulation or any other method."
In the near future, the researchers plan to test this approach in people with MCI.