Teenagers who smoked marijuana daily for three years performed poorly on memory tasks and showed abnormal changes in brain structure, according to a Northwestern Medicine study. Researchers in Chicago observed the brains of teenagers who were heavy users of marijuana. In those individuals, memory-related structures in the brain appeared to shrink and collapse inward, possibly indicating a decrease in neurons.
These abnormalities were recorded two years after the teens stopped using marijuana, possibly indicating long-term effects, and look similar to schizophrenia-related brain abnormalities.
The brains were shaped more abnormally for individuals who began marijuana use at a younger age, according to the reports, which suggest that memory regions of the brain are more susceptible to the drug at earlier ages.
The research was published in the December issue of Schizophrenia Bulletin.
Participants in the study spent close to a half-hour every day meditating or practicing some other mindfulness exercise (notable because most people associate meditation with sitting and thinking quietly, and that’s not the only type of exercise done in the study) for about eight weeks. They got MRIs of their brains before and after the eight week exercise, and when the study was over, many of the study’s 16 participants showed significant changes in the areas of the brain associated with behavior, memory, and stress. For more click the link below.
New NIDA-funded research shows that heavy marijuana use (at least four times per week over the past six months) is linked to adverse changes in the function and structure of brain areas associated with reward, decision making, and motivation. Heavy marijuana use can also enhance some brain circuits – possibly to compensate for reduced function in specific brain regions. This effect was more pronounced in those who started using at a young age, indicating that developing brains are particularly vulnerable to marijuana’s effects.
Although further long-term studies are needed to determine whether marijuana caused these effects, these scientific findings add to the growing literature showing that heavy marijuana use may harm the brain.
For a copy of the abstract (published online November 10), go to www.pnas.org/content/early/2014/11/05/1415297111.abstract.