Depressive symptoms, anxiety, and cannabinoids in patients with a primary brain tumor

The overall aim of this thesis was to gain a deeper understanding of mental health symptoms in patients with a primary brain tumor and to investigate a potential treatment for these symptoms. Depressive and other mental health symptoms are common and burdensome in patients with a primary brain tumor. Among patients in the stable phase of disease, fatigue, memory problems, reduced physical fitness, difficulty concentrating, and drowsiness were among the most frequent and burdensome symptoms. Depressive thoughts, anxiety, irritability, stress, and worrying about the future were also frequently reported. Several factors were associated with depressive symptoms. In patients with diffuse glioma, depressive symptoms were related to sex, tumor and resection location, fatigue, language dysfunction, and pre-existing depressive symptoms. Both the presence and absence of depressive symptoms were associated with tumors in specific brain regions, suggesting that local tumor effects may contribute to mood symptoms. After surgery, depressive symptoms remained common, and resection location was also associated with postoperative depression scores. Baseline depressive symptoms, greater fatigue, and worse language function were associated with more depressive symptoms one year after surgery. Beyond brain tumor-specific factors, sexual distress was independently associated with depressive symptoms in adolescents and young adults with or after cancer. The second part of this thesis investigated cannabis and cannabinoids as a potential treatment for symptoms. Cannabis use was relatively common among Dutch patients with a primary brain tumor: 14% were active users, while 19% had used cannabis currently or previously for tumor-related reasons. Symptom relief was the most frequently reported reason for use, particularly for sleep problems, anxiety, worrying, and depressive symptoms, although some patients also used cannabis because of presumed tumor-inhibiting effects. Cannabidiol (CBD) was generally preferred over Δ9-tetrahydrocannabinol (THC). Despite these patient-reported experiences, a meta-analysis of patients with neurologic or oncologic diseases found no evidence that cannabinoids improve health-related quality of life or mental well-being, although the available evidence was generally of limited quality and predominantly concerned THC. Finally, a randomized trial of CBD for anxiety in patients with a primary brain tumor was terminated early because of insufficient recruitment and was therefore underpowered. Within this small sample, however, there was no evidence of a beneficial effect of CBD on anxiety. Overall, this thesis highlights the substantial burden and multifactorial nature of mental health symptoms in patients with a primary brain tumor, while currently providing little evidence to support CBD as a treatment for anxiety in this population.