Evidence grows that heavy marijuana use may harm the brain

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.

October 2014

Dr. Kevin M. Gray discusses why it’s the perfect time for discovering new evidence-based treatments for marijuana dependence. In an accompanying podcast, he discusses a clinical trial that examines NAC’s potential as a treatment for marijuana dependence among adults.

Regular marijuana users may have impaired brain reward centers

New research shows that regular marijuana users show impairments in the brain’s ability to respond to dopamine – a brain chemical that is involved in reward, among other functions.

Although this research can’t determine if regular marijuana use causes deficits in brain reward centers – or if users take marijuana to compensate for less reactive dopamine systems – these results could help explain why regular marijuana users are more prone towards depression, anxiety, irritability, and increased sensitivity to stress.

July 2014

Interventions that bolster self-control in childhood and early adolescence might shield ethnic and racial minority adolescents and young adults from the burden of both drug use and depressive mood.

July 2014

Within the 2 weeks prior to responding to a nationwide survey, 28 percent of high school seniors were in a vehicle whose driver had been using marijuana or another illicit drug, or had drunk 5 or more alcoholic drinks.

Social media can influence teens with pro-drug messages

Girl texting on her cell phone

A new NIDA-funded study analyzed the content and demographic reach of a popular pro-marijuana Twitter handle in 2013 and found that only ten percent of the messages mentioned any risky behaviors associated with marijuana use.

Study compares effectiveness of oral drug tests for recent marijuana use

A variety of oral drug testing devices are available to determine recent marijuana use. For the first time, a new NIDA study compares the ability of these devices to accurately detect specific cannabinoids – the chemical compounds found in marijuana. The researchers looked at diagnostic sensitivity, specificity, and efficiency of the tests. In particular, the study identified devices that perform better at determining cannabinoid concentrations within certain time periods of detection in occasional and frequent users.

May 2014

Driving under the influence of marijuana is a dangerous public health concern. NIDA researchers have discovered that breath expelled into a Breathalyzer-style collection device contained measurable amounts of THC for up to 2 hours after participants in a recent clinical trial smoked the drug.

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