New research by a Japanese team has revealed that people’s long-term memories can be improved by taking a large dose of a dizziness medication that boosts the amount of histamine in the brain.
The conclusion of the research, which appeared in the American journal Biological Psychiatry on Tuesday, may have future implications for treating memory disorders such as Alzheimer’s disease.
Histamine in the central nervous system is linked to learning and memory, with long-term memory defined as memory prior to 48 hours ago.
The medication is usually prescribed at low dosages to treat those who suffer from dizziness. But in the memory experiment participants were given higher dosages to boost their histamine levels.
The trial was conducted on 38 men and women who were asked to study images of 128 objects. Their memory was then tested a week later and again two days after that, where they were asked if they had seen the items before.
Half of the test subjects were given an oral placebo while the other half were given the drug 30 minutes before the first test started. In the second test, those who had received the placebo earlier received the drug, while those who had initially received the drug were given the placebo.
The ratio of correct answers provided by those who responded after taking the drug stood at 46 percent, a 3 point increase over their scores when they did not take the medication.
Experiments showed that the test scores also varied significantly according to original memory capability.
Those who originally had a poor memory improved their scores from 28 percent to 55 percent after taking the drug.
In contrast, those who had a naturally good memory struggled after taking the drug. The percentage of correct responses declined from 61 percent to 39 percent.
Researchers suspect that for the latter group, the extra histamine may have added too much “noise” and excessive nerve signaling that hindered recall.
However, the trial does not suggest that improved long-term memory is always beneficial.
“There are still uncertainties surrounding the use of this medication, and people could recall bad memories from the past,” cautioned Yuji Ikegaya, a University of Tokyo professor who was part of the research team. “People shouldn’t take the medication based on their individual judgment.”