A new study found that the recreational use of marijuana alters the size and shape of the brain region responsible for emotions and motivations. This finding strongly opposed earlier studies that casual use of marijuana does not have negative effects.
According to the National Survey on Drug Use and Mental Health (NSDUH), about 18.9 million in the United States are using or have used marijuana recently, making it the most illicit drug in the continent. Some medical experts argue that the occasional use of it does not pose bar health effects, but this study proves otherwise.
Researchers from the Northwestern University and Harvard Medical School's Massachusetts General Hospital found that even occasional use of marijuana in young adults can have significant effects in the size and shape of their nucleus accumbens and amygdala -- parts of the brain responsible for emotion and motivation.
They recruited young adults aged 18 to 25 years old who have reported marijuana use about once a week. The participants underwent magnetic resonance imaging (MRI) to get a vision of their brain and compared them with the MRI results of young adults who have never used marijuana. They were also interviewed about their consumption and length of use of marijuana.
Their analysis revealed that the nucleus accumbens -- part of the brain responsible in reward processing -- of marijuana users are bigger than those who have not smoked marijuana. Its shape was also altered.
Additionally, they found that the more marijuana consumed; more irregularity is observed in the nucleus accumbers and amygdala -- part of the brain mainly responsible for one's emotions.
"This study suggests that even light to moderate recreational marijuana use can cause changes in brain anatomy. These observations are particularly interesting because previous studies have focused primarily on the brains of heavy marijuana smokers, and have largely ignored the brains of casual users," said Carl Lupica, PhD, in a press release. Lupica is not part of the study but he studies drug addiction at the National Institute on Drug Abuse.
Further details of this study can be read in the April 16 issue of The Journal of Neuroscience.
