THC Linked to Neuropsychiatric Aspect Results in Older Adults

Study data published on JAMA Network Open describe the potential adverse effects of therapeutic use of delta-9-tetrahydrocannabinol (THC) in older adults. In a meta-analysis of the literature, THC exposure was linked to an increased incidence of dizziness and lightheadedness in adults over 50 years of age. THC exposure was also associated with impaired thinking or perception, including dissociation.

While the association between THC exposure and psychotic symptoms in adolescents and young adults is well documented, the exact relationship in older adults is unknown. To clarify the possible side effects of THC exposure in older adults, the researchers conducted a systematic review of randomized controlled trials (RCTs) that reported the safety and effectiveness of various cannabinoid-based drugs (CBM) in adults over the age of 50. Studies published before November 2020 could be included.

The results of interest were all adverse events that occurred during exposure to CBMs. The pooled effect sizes were estimated for each adverse event and expressed as incident rate ratios (IRRs). The relationship between THC or cannabidiol (CBD) dose and the severity of adverse events was examined separately using meta-regression analysis.

A total of 30 studies examined the effects of CBMs with only THC on a total of 1417 people. The mean age in the pooled cohort was 59.5 years and 53.0% were men. Additionally, the researchers identified 24 studies describing the effects of combining CBD and THC. The pooled cohort from these studies comprised 1917 patients (mean age 58.2 years; 49.5% men).

In pooled analyzes of THC-only studies, a significant dose-response relationship was observed between THC and dizziness and lightheadedness. At a dose of 10 mg / d, the IRR of dizziness or lightheadedness was 2.04 (95% CI, 1.51-2.75). At a dose of 20 mg / d this IRR increased to 3.33 (95% CI, 2.43-4.58).

THC exposure was also associated with an increased risk of thinking or cognitive disorders, including dissociative disorders, in THC-only studies. In particular, at doses of 10 mg / d and 20 mg / d, the IRRs for impaired thinking or perception were 1.92 (95% CI, 1.32-2.80) and 3.84 (95% CI, 2.27), respectively -6.50). No other neuropsychiatric adverse events were significant in the pooled analyzes.

In this large-scale analysis of CBMs, higher THC exposure in older adults was associated with an increased incidence of dizziness, lightheadedness, and certain psychiatric symptoms. These associations were only present in RCTs that rated THC and not in studies that looked at the combination of THC and CBD.

More studies are needed to better understand the potential side effects of therapeutic CBM in older adults, particularly those over 65 years of age. In addition, the use of self-reporting metrics for adverse events instead of data from medical records may have resulted in bias.

“[T]These results suggest that CBMs containing THC should be used with caution in people aged 50 and over, particularly given the fact that dizziness or lightheadedness can increase the risk of falls in older adults, ”the researchers write.

Disclosure: A study author stated links to the pharmaceutical industry. For a full list of the authors’ information, see the original reference.


Velayudhan L, McGoohan KL, Bhattacharyya S. Assessment of THC-related neuropsychiatric symptoms in adults aged 50 and over: A systematic review and metaregression analysis. JAMA Netw Open. 2021; 4 (2): e2035913. doi: 10.1001 / jamanetworkopen.2020.35913.

This article originally appeared on Psychiatry Advisor

Related Articles