Long-term heavy marijuana use has only “minimal” impact on brain, cognition

London, United Kingdom–(ENEWSPF)–July 30, 2009. The consumption of cannabis, even long-term, has a “minimal” impact on brain function, according to a systematic literature review published online this week by the journal Psychological Medicine.

An international team of investigators from the United Kingdom, Spain, Brazil, Australia, and Switzerland conducted a systematic review of the effects of cannabis on brain structure and function.

Authors wrote, “We reviewed literature reporting neuroimaging studies of chronic or acute cannabis use published up until January 2009. … Sixty-six studies were identified, of which 41 met the inclusion criteria. Thirty-three were functional (SPECT/PET/fMRI) and eight structural (volumetric/DTI) imaging studies. … Only three of the structural imaging studies found differences between users and controls.”

Investigators concluded, “Minimal evidence of major effects of cannabis on brain structure has been reported,” noting that cannabis users and controls perform similarly on cognitive tasks.

According to a 2001 study published in the journal Archives of General Psychiatry, long-term cannabis smokers who abstained from pot for one week “showed virtually no significant differences from control subjects (those who had smoked marijuana less than 50 times in their lives) on a battery of 10 neuropsychological tests.” Investigators added, “Former heavy users, who had consumed little or no cannabis in the three months before testing, [also] showed no significant differences from control subjects on any of these tests on any of the testing days.”

While this is great news, what if the tests had shown chronic marijuana use does cause severe brain damage to long term users?  Do we determine whether adults should be locked up for what they ingest based on the harms of long-term heavy use?  If so, why are alcohol and tobacco allowed — we know they cause severe damage to lungs, heart, kidneys, liver, skin, and brain!

I’m all for religious use of ganja, medical use of cannabis, and the fact that social use of marijuana is safer than alcohol.  Whatever reason is fine by me, because I believe from the borders of my skin inward that territory is mine and only I can make laws to govern it.  If I want to put drain opener in my body, that is my right (well, not for long, as I would die quickly…); if I want to slam my head against a brick wall, that is my right; if I wish to inhale the smoke of a smoldering flower, that is my right.  If I am allowed to hurl my body out of an airplane while wearing a parachute, or jump off a tall bridge with a rubber band around my feet, or walk across fiery hot coals barefoot to get my kicks, why can I not smoke marijuana in the privacy of my home?