THC Leads to Increased Neuropsychiatric Events in Older Adults

The use of cannabinoid-based medicines (CBMs) containing delta-9-tetrahydrocannabinol (THC) increased the risk of certain neuropsychiatric adverse effects in adults 50 years of age or older, according to a systematic review of randomized control trials (RCTs).

Those researchers, led by Latha Velayudhan, MD, Department of Old Age Psychiatry, Institute of Psychiatry, Psychology, and Neuroscience, Division of Academic Psychiatry, King’s College London, London, concluded that those RCTs demonstrated a significant positive association between THC dose and incidence rate ratio for dizziness, lightheadedness, and thinking or perception disorder. Their systematic review and metaregression analysis was published as a research letter in JAMA Network Open.

According to Velayudhan and colleagues, an increased risk of psychotic symptoms or disorders, as well as poor outcomes in those individuals with an established psychotic disorder, has been associated with the regular use of cannabis high in THC — an association “well recognized among young people, the age group most often affected by psychosis,” they noted. However, the questioned remained as to whether these associations were also true for older adults taking CBMs.

The authors performed a systematic review and metaregression analysis of RCTs published between 1990 and 2020, which included 30 RCTs using THC-only CBMs and 24 RCTs using CBMs with different combinations of cannabidiol (CBD) and THC.

They found there was a positive association between THC dose and incident ratios for dizziness or lightheadedness (estimate, 0.05; 95% CI, 0.02-0.08) and thinking or perception disorder (estimate, 0.07; 95% CI, 0.03-0.11) for THC studies. However, they found there was no association with other neuropsychiatric adverse events for THC or THC and CBD combination studies.

The authors noted that a key limitation of their analysis was the fact that there were only four studies in which all the participants were 65 years or older, and thus too few to conduct sensitivity analyses for patients that age. Other limitations included the use of self-reporting in the included studies, rather than structured questionnaires — which could result in underreporting of adverse effects — and incomplete tolerability reporting.

Velayudhan and colleagues suggested that CBMs should be used cautiously in patients 50 years and older, particularly since dizziness and lightheadedness could increase the risk of falls for older patients.

In a commentary accompanying the research letter, Donna M. Fick, PhD, RN, GCNS-BC, Penn State College of Nursing, University Park, Pennsylvania, noted that one of the problems with drug studies of older adults is the paucity of data on those 65 years or older. These are individuals most likely to be taking multiple medications for multiple comorbidities, and, therefore, are more likely to have complex medication issues.

“Clearly, more studies of safety and efficacy should be conducted with adults aged 65 years and older, who are looking for nonopioid solutions to chronic, persistent pain and other conditions for which CBMs are commonly prescribed,” wrote Fick. “Although this study reported important and critical information about psychotic AEs in older adults using CBMs, it contained too few older adults aged 65 years and older.”

Furthermore, Fick noted that the adverse events associated with THC — alterations in thinking, dizziness, and lightheadedness — could lead to falls or delirium, both of which can have poor outcomes for older patients. “We should not abandon best practices in the care of older adults by looking for simple solutions in pharmaceuticals that could be doing more harm than benefit,” she warned.

Fick added that more research on adults 65 years and older is essential because they could be taking CBMs without the necessary data needed to make decisions about using either THC or CBD. These studies should include more adults over the age of 65, those with multiple comorbidities, and THC formulations of various doses and duration, she wrote.

“Finally, as clinicians, we often feel the need to do something for patients, and medication can be an easy but harmful solution,” Fick noted. “Studies and education are also needed for nonpharmacologic approaches to such conditions as pain, for which CBMs are often given… Clinicians should use an individualized approach with these products that considers the potential of other drug-drug interactions, multiple comorbidities, and care aligned with the priorities of the older adults. Once again, less really is more for improving care in older adults.”

1. The use of cannabinoid-based medicines that primarily contain THC in older adults is associated with an increased risk of certain neuropsychiatric adverse events, including dizziness, lightheadedness, and thinking or perception disorder.

2. These medications should be used cautiously in adults 50 years and older, researchers concluded.

Michael Bassett, Contributing Writer, BreakingMED™

Cat ID: 192

Topic ID: 86,192,730,130,192,144,925