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New study: No link between cannabis and cognitive decline in seniors

New study: No link between cannabis and cognitive decline in seniors

Frequent cannabis use does not necessarily result in cognitive decline in seniors, according to the findings of a new study.

The researchers found that medical marijuana patients and non-users “did not significantly differ in terms of cognitive performance measures. Furthermore, none of the MC (medical cannabis) use patterns associated with cognitive performance.” 

The report, published in Drug and Alcohol Review, was meant to “assess the relationship between long-term medical cannabis use and cognitive function in a sample of middle-aged and old chronic pain patients.”

The cross-sectional study looked at chronic pain patients aged 50 and up who had medical marijuana licenses, and compared them to a group of people the same age who do not use marijuana. The researchers used psychomotor reaction, attention, working memory, and new learning using CogState computerized brief battery, and regression models and Bayesian tests to compare their cognitive performance.

The researchers concluded that the results of the study “suggest that use of whole plant MC does not have a widespread impact on cognition in older chronic pain patients,” and that their research “could be a first step towards a better risk–benefit assessment of MC treatment in this population.”

According to Dr. Galit Weinstein, one of the researchers who compiled the report, “in addition to comparing users and non-users, we also focused on the cannabis users only and tested whether doses (i.e. strength) and frequency of use were related to cognitive function. We found no statistically significant association, which further supports the main message of the study, that cannabis use in old age may not have effects on cognitive function.”

Of course there is a difference between the cognitive effects one experiences when under the influence of cannabis and any potential lasting effects. “Individuals who are acutely intoxicated tend to demonstrate deficits in cognitive performance, particularly in memory and the ability to learn new information,” Weinstein told the Cannigma. “However, these effects subside together with the ‘high’ sensation. In the current study we focused on the non-acute, or long-term implications of cannabis use on the brain. This is particularly important in the older population who is prone to brain degeneration, cognitive decline and dementia, including Alzheimer’s disease.”

The medical cannabis patients had on average used marijuana for four years with an average consumption of 31 grams per month, and 33 dosages/sessions per week. The most common mode of intake was smoking (68.6%) followed by oil extracts (21.4%), and vaporization (20%). The average THC level of the cannabis used was 15.9 ± 6.2% and the average CBD level was 2.7 ± 3.7%.

The study was carried out by researchers from the Technion University and Haifa University in Israel, where 25% of the medical cannabis patients are over 65 years old, according to the study. Chronic pain is the most common condition cannabis is prescribed for in Israel, with an average monthly prescription of 34 grams. 

Dr. Weinstein said that “we chose to focus on chronic pain because it is a common condition and among the first in terms of medical indications for cannabis prescriptions. Future studies are indeed warranted to assess the effects of cannabis use in elderly patients who use cannabis for other medical conditions.”

The test population for the study was a group of 63 medical cannabis patients and 62 patients who do not have a medical cannabis license. The researchers excluded anyone diagnosed with Parkinson’s disease, anxiety or serious mental illness, post-traumatic stress disorder, clinical dementia, multiple sclerosis, brain tumor, traumatic brain injury, stroke and cancer patients who currently receive chemotherapy, and individuals who do not understand Hebrew. All of the medical cannabis patients were required to have been using cannabis for at least one year prior to the study.

The average of the total sample population was 61 years old and 48.8% of the subjects were men. And while the medical cannabis patients were on average three years older (63 years vs. 60 years) and were more likely to have depression (21% vs 7%) or cardiovascular disease (21% vs 3%), they otherwise had very similar gender distributions, education levels, and alcohol and cigarette use patterns, according to the researchers.  

One limitation of the study, the researchers write, was that they were not able to test the subjects’ cognition prior to starting marijuana use, and therefore cause and effect inferences weren’t able to be made.

Also, they did not collect information on what cannabis chemovars were used, or on other analgesics or psychoactive medicines used by the test subjects.

The researchers stated that the cognitive assessment they used “was a brief battery and may have limited sensitivity” and that “it is possible that cannabis affects cognition in domains other than the ones examined in the current study.”

In their conclusion, they state that “considering the accumulating evidence showing efficacy of cannabis use for multiple health conditions common in older individuals, the lack of adverse effects on the brain in the current sample of individuals with chronic pain who were older than 50 years can contribute to a better risk–benefit assessment of MC treatment in this population.”

This is by no means the first study to look at cognitive decline and cannabis use, although its design appears more meticulous than previous studies. 

A 2012 study found that persistent cannabis use “was associated with neuropsychological decline broadway across domains of functioning, even after controlling for years of education.”

Another study that looked at a total of 856 individual twins from 428 families “found little support for a potential causal effect of cannabis use on cognition, consistent with previous twin studies.”

Meanwhile, a systematic review published earlier this year looked at decades of research on mothers who use cannabis while pregnant and found that “the evidence does not support an association between prenatal cannabis exposure and clinically relevant cognitive effects.”

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