Treatment with highly purified cannabidiol among epilepsy patients is associated with increases in neural activity in prefrontal brain regions related to verbal memory and attention, according to new research published in Epilepsy & Behavior. But the treatment does not appear to significantly impact working memory performance.
“We were interested in better understanding highly purified CBD’s effects on working memory for several reasons,” said study author Tyler E. Gaston of the University of Alabama at Birmingham.
“First and foremost, with the FDA approval of Epidiolex, neurologists who may prescribe this medication for their epilepsy patients need to know if there are any untoward effects on memory that could be attributed to the medication. This is important because people with epilepsy already can suffer from memory difficulties.”
“Further, there have been some documented negative effects of other cannabis products on cognition, Gaston said. “We wanted to determine if purified CBD had any effects such as this.”
In the study, the researchers examined the brain activity of 20 patients with treatment-resistant epilepsy prior to initiation of CBD treatment and after reaching a stable dosage. Gaston and his colleagues also recruited 23 healthy volunteers, who served as a control group.
“Our study used a tool called functional MRI (fMRI) to look at changes in brain activity as a result of starting treatment with CBD. The participants did a working memory task while they were being scanned, and this is how we can determine any changes or differences in neural activity for working memory,” Gaston explained.
As expected, working memory performance tended to be worse among the epilepsy patients compared to the control group. The researchers also found no evidence that CBD treatment resulted in significant changes in working memory performance. But they did observe increases in activation of the inferior frontal gyrus and insula after CBD treatment.
The findings provide some preliminary evidence that may CBD can help to “normalize” attentional and memory processing.
“Purified CBD does not have a significant effect either positively or negatively on working memory performance in people with epilepsy. We did, however, note that after CBD treatment that there some increases in brain activity in regions of the brain important for verbal memory and attention,” Gaston told PsyPost.
The study — like all research — includes some limitations.
“There were several things we could not control for in our study, including type of epilepsy, number and type of other seizure medications taken, and some variability in the dose of CBD taken by participants at the time of their follow up fMRI,” Gaston explained. “Therefore, we cannot comment on whether any of these specific aspects may influence the effects of CBD on working memory and fMRI activity. Our study also just investigated adult patients, it will be helpful in the future to investigate if there are differences in brain activity in adolescents and children.”
“It is important to note that these data/results can only be applied to the FDA-approved product which is highly purified CBD, and cannot be extrapolated to other cannabis products,” he added.
The study, “Effects of highly purified cannabidiol (CBD) on fMRI of working memory in treatment-resistant epilepsy“, was authored by Tyler E. Gaston, Jane B. Allendorfer, Sangeeta Nair, E. Martina Bebin, Leslie P. Grayson, Roy C. Martin, and Jerzy P. Szaflarski.