CBD combined with the chemotherapy drug temozolomide produced antidepressant-like effects in an animal model, according to a study published in Frontiers in Pharmacology, suggesting potential for treating depression associated with glioblastoma.

Researchers from the University of the Balearic Islands examined whether CBD could help address depression associated with glioblastoma, an aggressive form of brain cancer commonly treated with temozolomide.

The study involved 241 adult male and female rats. Researchers administered temozolomide, CBD or the antidepressant fluoxetine alone and in combination before evaluating the animals using a forced-swim test, a behavioral screening tool frequently used in preclinical antidepressant research.

Temozolomide administered over two treatment cycles produced antidepressant-like responses among the rats when males and females were analyzed together, including reduced immobility and increased climbing and swimming behavior.

CBD alone also produced antidepressant-like effects, but the results depended on the animals’ sex. Male rats receiving either 10 or 30 milligrams of CBD per kilogram of body weight showed reduced immobility and increased climbing, while the same effects were not observed in females.

When CBD was combined with temozolomide, male rats again displayed reduced immobility and increased climbing compared with males receiving temozolomide without CBD. The combination did not produce a statistically significant benefit when male and female rats were analyzed together.

Fluoxetine produced dose-dependent antidepressant-like effects when administered alone. However, combining fluoxetine with temozolomide did not provide a measurable improvement over the effects associated with the drugs individually.

Researchers said the findings suggest CBD could eventually offer a way to address depressive symptoms among patients receiving temozolomide for glioblastoma, potentially providing both antidepressant-like and previously reported antitumor benefits.

However, the researchers emphasized that the experiment involved healthy rats without glioblastoma. Additional studies using animal models of the disease are needed before determining whether the results could apply to humans. Future research will also be needed to examine why the CBD combination was effective only among male rats and whether different doses could produce benefits in females.