Methylene blue appears to improve short-term memory

by Bruce Sylvester: One dosing with methylene blue appears to increase MRI-based response in brain areas that control short-term memory and attention, researchers reported on June 28 in Radiology. Methylene blue is currently used to treat methemoglobinemia.

“Although the memory-enhancing effects of methylene blue were shown in rodents in the 1970s, the underlying neuronal changes in the brain responsible for memory improvement and the effects of methylene blue on short-term memory and sustained-attention tasks have not been investigated,” said investigator Timothy Q. Duong, Ph.D., professor of ophthalmology, radiology, and physiology  at the University of Texas Health Science Center at San Antonio, Texas. “Our team decided to conduct the first multi-modal MRI study of methylene blue in humans.”

The researchers enrolled 26 healthy subjects, ages of 22-62 years, in the  double-blind, randomized, placebo-controlled clinical trial.  

The subjects underwent functional MRI (fMRI) both prior to dosing and one hour after dosing with low-dose methylene blue or placebo. The researchers evaluated effects of methylene blue on cerebrovascular reactivity during specifically designed tasks. They also measured mean cerebral blood flow pre- and post-treatment.

They reported that methylene blue increased response in the bilateral insular cortex, a brain region associated with emotional responses, during a task evaluating reaction time to a visual stimulus.

MRI results also indicated increased response during short-term memory tasks involving the prefrontal cortex, which controls processing of memories, the parietal lobe, primarily associated with the processing of sensory information, and the occipital cortex, the visual processing center of the brain.

Methylene blue treatment also correlated to 7 percent increase in correct in responses during memory retrieval.

“This work certainly provides a foundation for future trials of methylene blue in healthy aging, cognitive impairment, dementia and other conditions that might benefit from drug-induced memory enhancement,” Duong said.