Could it also improve Alzheimer’s, long-term memory?
Methylene blue, tried and tested to be “very safe,” has been used for more than a hundred years as a stain and to treat medical disorders like methemoglobinemia, cyanide and carbon monoxide poisoning. Recently published data suggest that it could also enhance short-term memory and attention.
This was the finding of a study published in the June 28 issue of Radiology using functional MRI (fMRI), after a single oral dose of methylene blue. An increased brain activity in the bilateral insular cortex, as well as the prefrontal cortex and parietal and occipital lobes, compared with placebo, has been demonstrated in the fMRI.
Timothy Q. Duong, PhD, from the University of Texas Health Science Center at San Antonio, said that no other clinically approved drug is used to improve memory, making methylene blue “unique and novel in that sense.”
The beneficial effect of methylene blue on memory has been researched since the 1970s, after it has been shown in rodents to have memory-enhancing effects. However, there were no sufficient data obtained in the underlying neuronal mechanisms and the drug’s impact on short-term memory and sustained attention.
This current study was a randomized, double-blinded, placebo-controlled clinical trial enrolling 26 healthy individuals aged 22 to 62 years, who were randomized to single-dose administration of methylene blue 280 mg or a blue food colorant as placebo.
A psychomotor vigilance task to test sustained attention and a delayed match-to-sample task to measure short-term memory were done while undergoing fMRI, both before and one hour after administration of the study drug or placebo.
In addition, the researchers tested the effect of methylene blue on cerebrovascular reactivity by determining cerebral blood flow during a carbon dioxide challenge before and after administration. During the psychomotor vigilance task, methylene blue was associated with significantly increased activity on fMRI in the bilateral anterior and posterior insular cortices during the attention phase (P = .01-.008).
Methylene blue was also associated with significantly increased fMRI activity during the short-term memory task in the bilateral occipital lobes, the basal ganglia, the thalami, the parietal lobules, the anterior cingulate gyrus, and the cerebellum (P = .03-.0003).
After orally taking methylene blue, an approximately 7 percent increase in the number of correct behavioral responses (P < .01) was noted, while no change was observed in the placebo group. There were also no significant changes in cerebral blood flow with placebo.
“The results support the notion that methylene blue enhances memory performance and functional MR imaging activity in brain regions associated with a visuo-spatial short-term memory task,” the researchers wrote in their paper. These findings are “consistent with behavioral measurements in the same subjects,” added the authors.
This current study was only for short-term memory and did not examine the impact of methylene blue on long-term memory. The same group of researchers are currently conducting a clinical trial of the drug in patients with mild cognitive impairment and Alzheimer’s disease. The trial is expected to be completed early next year. With reports from Radiology and Medscape
Vital Signs July 1-31 2016