Long term effects of cannabis on brain structure

The effects of long-term marijuana use on brain structure may depend on the age of first use and the time span of use, a study suggests Francesca M filbey and colleagues studied changes in brain structure and connectivity, taking into account possible biases such as gender, age, ethnicity, age of first use of marijuana, and time span of use The authors studied 48 adult marijuana users and 62 sex - and age matched non users who reported several differences in brain gray matter capacity and white matter connectivity These findings suggest that long-term marijuana use may be associated with decreased gray matter volume and increased structural and functional connectivity in the orbitofrontal cortex (OFC) Additional tests revealed that the early emergence of regular cannabis use may be related to increased functional connectivity of white matter, while long-term cannabis use may be related to reduced structural connectivity This study provides a preliminary indication that in terms of δ - 9-tetrahydrocannabinol, the main component of marijuana for mental function, grey matter of orbital frontal cortex (OFC) may be more vulnerable than white matter The authors say the study suggests that long-term use of cannabis may regulate complex neuroadaptive processes, but further research is needed to determine whether these changes are reversible after the end of cannabis use Original search: Francesca M filbey, Sina Aslan, Vince D Calhoun, Jeffrey S Spence, Eswar damaraju, Arvind caprihan, and Judith Segal Long term effects of marijuana use on the brain PNAs, November 10, 2014; doi: 10.1073/pnas.1415297111