Medical scientist studying the effects of marijuana use are currently reporting findings of alterations of brain regions involved in motivation and emotion, and are also looking forward to studying how alterations in brain regions are related to memory impairments and Cannabis use disorder.
According to a study to be published April 16 in The Journal of Neuroscience, the size and shape of two brain regions involved in emotion and motivation may differ in young adults who smoke marijuana at least once a week. The nucleus accumbens — a brain region known to be involved in reward processing — was larger and altered in its shape, density and structure in the marijuana users compared to non-users. The amygdala — a brain region that plays a central role in emotion also differed in shape and density.
President Barack Obama talks to CNN’s Jake Tapper about marijuana legalization in an exclusive interview.
The research findings suggest that recreational marijuana use may lead to previously unidentified brain changes, and highlight the importance of research aimed at understanding the long-term effects of low to moderate marijuana use on the brain. The release from the Journal of Neuroscience Tuesday did not mention a dysfunctional connection with the altered brain regions, but did report that the findings highlight the need for greater understanding of the long-term effects of low-to-moderate marijuana use on the brain.
In the current study, Jodi Gilman, PhD, Anne Blood, PhD, and Hans Breiter, MD, of Northwestern University and Massachusetts General Hospital/Harvard Medical School used magnetic resonance imaging (MRI) to compare the brains of 18- to 25-year olds who reported smoking marijuana at least once per week with those with little to no history of marijuana use.
Recently Hans Breiter, MD has been involved in another research study that may have greater significance than the above study picked up by the media this week. A study released in March 2014 in the Schizophrenia Bulletin
Cannabis use is associated with working memory impairments; however, the relationship between cannabis use and working memory neural circuitry is unclear. Researchers examined whether a Cannabis Use Disorder (CUD) was associated with differences in brain morphology between control subjects with and without a CUD and between schizophrenia subjects with and without a CUD. Researchers also studied whether these differences related to Working Memory and CUD history.
Subjects group-matched on demographics included …
44 healthy controls,
10 subjects with a CUD history,
28 schizophrenia subjects with no history of substance use disorders,
and 15 schizophrenia subjects with a CUD history.
Large-deformation high-dimensional brain mapping with magnetic resonance imaging was used to obtain surface-based representations of the following brain structures …
striatum,
globus pallidus, and
thalamus
The structures were compared across groups, and correlated with Working Memory and CUD history.
MRI surface maps were generated to visualize morphological differences. There were significant cannabis-related parametric decreases in Working Memory across groups.
Similar cannabis-related shape differences were observed in the striatum, globus pallidus, and thalamus in controls and schizophrenia subjects.
Cannabis-related striatal and thalamic shape differences correlated with poorer Working Memory and younger age of CUD onset in both groups.
Schizophrenia subjects demonstrated cannabis-related neuroanatomical differences that were consistent and exaggerated compared with cannabis-related differences found in controls.
The cross-sectional results suggest that both CUD groups were characterized by Working Memory deficits and subcortical neuroanatomical differences. Future longitudinal studies could help determine whether cannabis use contributes to these observed shape differences or whether they are biomarkers of a vulnerability to the effects of cannabis that predate its misuse.
Hans Breiter, MD works in the Department of Psychiatry and Behavioral Sciences at Northwestern University. He participates in studies involving MRI, Brain Mapping, the Amydgala, cocaine, Obsessive Compulsive Disorder, cocaine-related disorders, and short-term memory.
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