Medical Bulletin 1/December/2023

Here are the top medical news of the day:

Cannabis reduces long term opioid use no evidence found

A 20-year Australian study has found no evidence to suggest cannabis reduces illicit opioid use, and it may not be an effective long-term method of reducing harm for those with an opioid use disorder or problematic use of opioids.

Published in the American Journal of Psychiatry, the University of Sydney led study is one of the longest of its kind. Between 2001 to 2022, the study involved a group of 615 people with heroin dependence, many of whom also used cannabis.

Opioid use is currently responsible for more death and disability than any other illicit drug. Opioid and cannabis use disorders make up approximately 77 percent of all illicit drug disorders. The researchers say clinicians and policymakers should be cautious about relying on cannabis to reduce problematic opioid use or as a potential strategy to help manage the opioid crisis, especially given a global shift towards cannabis legalisation and recognition as a therapeutic product.

To examine the impact of cannabis on opioid use, and vice versa, researchers used a recently developed statistical technique. This allowed them to account for influential factors on opioid and cannabis use in the data such as age and made it possible to focus on individual changes in substance use over time.

“Our investigation shows that cannabis use remains common among this population, but it may not be an effective long term strategy for reducing opioid use ,” says lead author Dr Jack Wilson, from The Matilda Centre for Research in Mental Health and Substance Use, at the University of Sydney.

Reference: The long-term relationship between cannabis and heroin use: An 18-20-year follow-up of the Australian Treatment Outcome Study (ATOS); American Journal of Psychiatry

Connections between neuroinflammation and Alzheimer’s disease finds new study

Immune-regulating brain cells known as microglia are known to play a role in the progression of Alzheimer’s disease (AD). Study by Brigham investigators revealed how genetic changes in certain types of brain cells may contribute to the inflammatory response seen in Alzheimer’s disease

A new study by investigators from Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system, explores how the genetics of microglia contribute to neuroinflammation and, in turn, AD.

The team revealed that a reduction of INPP5D, a gene found in microglia, results in neuroinflammation and increases the risk for AD. Their results, which have important implications for the design of microglia-centered therapeutics for Alzheimer’s disease and related disorders, are published in Nature Communications.

They found lower levels of INPP5D in the tissues of patients with AD and when INPP5D was reduced, it activated inflammation. In parallel, they used living human brain cells derived from stem cells to study the intricate molecular interactions within microglia that mediate inflammatory processes with a reduction of INPP5D. These studies identified specific proteins that could be inhibited to block inflammasome activation in microglia.

“Our results highlight an exciting promise for INPP5D, but some questions still remain,” said Young-Pearse. “Future studies examining the interaction between INPP5D activity and inflammasome regulation are essential to improve our understanding of microglia in AD and to help develop a comprehensive toolbox of therapeutics that can be deployed to treat each of the molecular roads that lead to AD.

Reference: Chou, V et al. “INPP5D regulates inflammasome activation in human microglia” Nature Communications. 

Addiction cravings reduced by 'vivid imagery'

Since cravings are maintained and heightened by sensory imagery stored in memories, with more vivid imagery predicting higher craving intensity, one of the goals of the FAU study was to transform dysfunctional memories stored in the brain through processing and integration. Addiction memory, assumed to be episodic, resembles the maladaptive traumatic memory formation commonly seen in post-traumatic stress disorder.

New research shows promise in treating addiction cravings by combining eye movements and guided instructions to process memories. Researchers transformed dysfunctional memories stored in the brain through processing and integration. EMDR was as effective as cognitive behavioral therapy for cravings with the combination of both resulting in more reduction in craving than cognitive behavioral therapy (CBT) alone. Both groups (experimental group and control group using only CBT) had clinically significant reductions in cravings, repetitive negative thoughts, and irrational cognitions, with the experimental group showing greater decreases overall.

Results of the study, published in the Journal of Evidence-based Social Work, showed a significantly high participant retention rate. Addiction-focused EMDR was as effective as cognitive behavioral therapy for cravings with the combination of both resulting in more reduction in craving than cognitive behavioral therapy alone. Both groups (experimental group and control group using only cognitive behavioral therapy) had clinically significant reductions in cravings, perseverative thoughts, and irrational cognitions, with the experimental group showing greater decreases overall.

Currently, individuals with substance use disorder are encouraged to attend inpatient treatment that employs group therapy to educate patients on addiction, coping skills, and thought-stopping techniques, and cognitive behavioral therapy, along with pharmacological options such as anti-craving drugs.

Reference: Elizabeth Woodruff, Juyoung Park, Heather Howard, Manny Gonzalez, Talib Jaber. Feasibility and Efficacy of Addiction-Focused Eye Movement Desensitization Reprocessing in Adults with Substance Use Disorder. Journal of Evidence-Based Social Work, 2023; 1 DOI: 10.1080/26408066.2023.2271927