MONTREAL, July 14, 2020 – A new study has observed structural brain alterations associated with addiction that are similar or great than those reported for other psychiatric disorders.

Smaller brain volumes were observed in alcohol and cannabis dependent patient, relative to age and sex-matched non-dependent individuals, in regions that have also been shown to characterize patients with other psychiatric conditions, such as schizophrenia, bipolar disorder, major depressive disorder and attention deficit hyperactivity disorder (ADHD), reports the study, published online in July 2020 in Human Brain Mapping.

These results are consistent with previous studies on the structural alterations related to alcohol and cannabis use disorder in adults. “Our findings suggest that alcohol use disorders are associated with significantly smaller volumes in a number of brain regions, which have also been shown to be affected in patient with schizophrenia, bipolar disorder, and major depression.  The effects of alcohol on some brain regions were similar in magnitude to those reported for schizophrenia,” explains the study’s lead author, Xavier Navarri, master student at UdeM’s Department of Psychiatry and Addiction. The effects reported for cannabis were similar in magnitude, but the authors cautioned that the findings comparing heavy cannabis users to non-users showed high variability within studies, suggesting that there are large individual variations the relationships between cannabis misuse and brain structure.

“These results could have major clinical implications for promoting health equity across how we treat psychiatric conditions,” said Patricia Conrod, senior author and professor at UdeM’s Department of Psychiatry and Addiction. “Our results suggest that the relative impact of addiction on the brain is similar in magnitude to alterations reported for other major psychiatric conditions. Yet substance use disorders are seriously undertreated in society and lead to substantial societal and human costs,” further explains Conrod. “A better understanding of the brain-related impairments in addiction is important to promote health equity and better access to addiction rehabilitative services.”

Brain structures

Dr Conrod’s team is part of the ENIGMA-Addiction working group, an international collaboration of researchers who combined their imaging data to perform powerful statistical analyses on large sample sizes. The study combined data from 435 participants with alcohol use disorders when compared to 363 controls from seven site and  200 participants reporting heavy cannabis use or cannabis use disorder compared to 247 non-using controls from seven different sites. A meta-analysis was performed to observe shared brain abnormalities across the sites in alcohol- and cannabis-dependent patients. The analyses were performed to estimate effect sizes for the different regions of the brain using identical methods used to identify brain correlates of  schizophrenia, bipolar disorder, major depressive disorder and ADHD by other working groups within the ENIGMA Consortium.

This study attempted to compare effect sizes in volumetric differences across psychiatric conditions. Results suggest that alcohol use disorder is associated with brain alterations that are similar in size to those reported for schizophrenia, and larger than those reported for major depression, in several brain regions. The regions of the brain that were most able to differentiate recently detoxified patients with alcohol use disorders from controls were subcortical regions that are part of the neurocircuitry of reward, habit formation, memory and stress reactivity. Reduced cortical thickness was observed between alcohol and cannabis dependents, as well as subjects with major depressive disorder. Most of the reduced cortical thickness in alcohol dependent patients were also observed in patients with schizophrenia or bipolar disorder. Cannabis use disorders were associated reduced volumes in some regions of the brain, which were similar in size to those observed for alcohol and other psychiatric conditions, but results for cannabis were more variable and require further study.

“Our research suggests reduced structural volumes in alcohol and cannabis use disorders are equivalent in magnitude to those reported previously for schizophrenia and bipolar disorder, and  greater than those observed for major depression and ADHD”. Such structural brain findings provide strong justification for increasing  access to addiction treatment and rehabilitative services. “People who suffer from addiction are less likely to receive treatment compared to people who suffer from other psychiatric conditions.  The results of this study argue for more equity across mental health and addiction services”, said Conrod.

Findings likely reflect the role of the brain in addictive behaviours and the impact of substance use in brain structures. The study demonstrates the need for cognitive remediation in recovery services for alcohol dependent patients, as well as other rehabilitative services.

About this study

Navarri X., Afzali M.H., Lavoie J., Sinha R., Stein D.J., Momenan R., Veltman D.J., Korucuoglu O., Sjoerds Z., van Holst R.J., Hester R., Orr C., Cousijn J., Yucel M., Lorenzetti V., Wiers R., Jahanshad N., Glahn D.C., Thompson P.M., Mackey S. and Conrod P.J. “How do substance use disorders compare to other psychiatric conditions on structural brain abnormalities? A cross-disorder meta-analytic comparison using the ENIGMA Consortium findings”, published in Human Brain Mapping, July 9 , 2020. Doi: https://doi.org/10.1002/hbm.25114.

This is study was supported by the following project grants: National Institutes of Health (NIH) Grant U54 EB 020403 with funds provided for the trans-NIH Big Data to Knowledge (BD2K) initiative; R01 MH116147 to PT, NJ, and PC; NIDA 1R01DA047119-01, awarded to Hugh Garavan and PC, and a Canada Research Chair, awarded to PC. Data collection: OK received support for the Neuro-ADAPT study from VICI grant no. 453.08.01 from the Netherlands Organization for Scientific Research (NWO) awarded to Reinout W Wiers. DV received funding for the TrIP study from ZonMW grant no. 31160003 from the Netherlands Organization for Scientific Research (NWO). DV received funding for the NESDA-AD study from ZonMW grant no. 31160004 from the Netherlands Organization for Scientific Research (NWO). RvH received funding for the ADPG study from ZonMW grant no.91676084 from the Netherlands Organization for Scientific Research (NWO). DV received funding for the DABIS study from VIDI grant no.016.08.322 from the Netherlands Organization for Scientific Research (NWO) awarded to Ingmar H A Franken. JC received funding for the Cannabis Prospective study from ZonMW grant no.31180002 from the Netherlands Organization for Scientific Research (NWO). RS received funds from NIH/NIDA: PL30-1DA024859 -01 and NIH/NCRR: UL1-RR24925-01. MY was supported by a National Health and Medical Research Council Fellowship (#1117188) and the David Winston Turner Endowment Fund.