Journal Article Annotations
2019, 3rd Quarter
Annotations by Franklin King IV, MD and Nicholas Kontos, MD
September 2019
Findings:
Cannabis use is common in patients with epilepsy. Epilepsy patients were found to demonstrate a significant and independent association between cannabis use and negative patient-reported outcomes, specifically, depression, quality of life, perceived disability due to epilepsy, and satisfaction with anti-epileptic drug treatment; this association remained significant after controlling for clinical, medical, social, and psychological variables. In addition, cannabis use exerted a significant mediating effect on the relationship between a positive history of a psychiatric disorder and self-reported depression severity and quality of life.
Strengths & Weaknesses:
The study benefits from a moderate sample size of 300 patients seeking epilepsy care at a tertiary academic medical center, with a robust quantity of data points collected relevant to the study aims. Weaknesses include failure to determine additional details on cannabis use such as motivation for use (ie, recreational vs medical), and dose-response relationships and tetrahydrocannabinol:cannabidiol ratio of products consumed. Clinical assessments of depression severity would also be useful to corroborate patient-reported outcome measures.
Relevance to Consultation-Liaison Psychiatrists:
With cannabis use on the rise, it is important for CL psychiatrists to be aware that not all medical sub-populations may be equal when it comes to negative versus positive effects of cannabis on psychiatric and medical conditions. The present study suggests that patients with epilepsy — a group commonly encountered by CL psychiatrists and one at a greater risk of depression than the general population — may be selectively more vulnerable to negative psychiatric effects from cannabis use, which has implications both for treatment of psychiatric conditions in this population as well as other behavioral elements, such as adherence to anti-epileptic drug treatment.
Type of study: Cross-sectional study
Findings:
Slowed processing speed is a core feature of cognitive impairment in traumatic brain injury and previous work has found that this may relate to deficits in dopaminergic functioning. Treatment with methylphenidate significantly improved processing speed (measured by a reaction time task) in TBI subjects who showed abnormal/low dopamine transporter (DaT) binding on SPECT, but not in those with normal DaT binding. In addition, methylphenidate improved apathy, but only in subjects with low DaT binding.
Strengths & Weaknesses:
The study benefits by a crossover trial design. Weaknesses include mainly the (relatively) small sample size of 40 subjects, and lack of examination of other neurotransmitter systems that might be impacted by methylphenidate therapy, such as the noradrenergic system.
Relevance to Consultation-Liaison Psychiatrists:
Long term cognitive difficulties are common in TBI patients and CL psychiatrists are often called upon as to whether a psychostimulant might be beneficial as a “cognitive enhancer”. Despite their frequent use, the evidence supporting psychostimulants is mixed and treatment response to stimulants when used for this purpose is highly variable. This study finds that among TBI patients, only those with low levels of striatal dopamine responded to stimulant treatment. While obviously not ready for “primetime”, these findings, if replicated, might offer a means of determining appropriate TBI candidates for stimulant therapy, while protecting those with a low likelihood of response from potential side effects.
Type of study: Randomized Controlled Trial