Washington, DC: The results of a recent study reporting hippocampal volume reductions in long-term, heavy users of cannabis are based on only 15 cases, and are inconsistent with previously published research, NORML Deputy Director Paul Armentano said today.
The widely reported study, published this week in the journal Archives of General Psychiatry, found that chronic cannabis smokers (who averaged at least five joints per day for a period of 20 years) experience a measurable (via structural magnetic resonance imaging) reduction in the hippocampus and amygdala compared to non-users.
Commenting on the new study, Armentano said that although the exceptionally heavy use of cannabis may pose unique yet subtle health hazards, these potential risks are likely irrelevant to the overwhelming majority of cannabis consumers who use the drug in moderation.
"While these preliminary results are a cause of concern, they must be replicated in a much larger sample size before we can begin making any determinations regarding whether there may exist a cause-and-effect relationship, or whether these results may hold any significance for the millions of Americans who consume cannabis on a far more limited basis," he said.
Armentano added that a previous assessment of long-term cannabis use on hippocampal volume found no adverse effects associated with marijuana use.
Numerous studies of cannabis use on neurocognitive abilities have also failed to indicate that marijuana use has residual adverse impacts on cognition.
Armentano concluded: "While we have known for decades that chronic alcohol use is toxic to the brain, this fact is not a justification for arresting and incarcerating the millions of Americans who enjoy a glass of wine or beer with dinner. As is the case with alcohol, the findings of this study – even if we are to take them at face value – are an argument in favor of legalization, education, and moderation – not criminal prohibition."