A single oral dose of methylene blue results in an increased MRI-based response in brain areas that control short-term memory and attention, according to a new study published online in the journal Radiology.

Methylene blue is used to treat methemoglobinemia, a blood disorder in which oxygen is unable to release effectively to body tissues, and as a surgical stain.

Animal studies have shown a single low dose of methylene blue enhances long-term contextual memory--the conscious recall of the source and circumstances of a specific memory--and extinction memory, a process in which a conditioned response from stimuli gradually diminishes over time.

"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 study author Timothy Q. Duong, Ph.D., from 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."

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