Heavy marijuana use may cause poor memory and abnormal brain structure, study says | PBS NewsHour
Quote de um cara no reddit sobre esse artigo ae
It's been awhile since this was posted, but after reading the journal article I can summarize a few things.
This study aimed to look at visualizing subcortical circuitry rearrangement in schizophrenic vs non-schizophrenic subjects, and compare marijuana use between both. For you neuro-anatomists out there, subcortical includes the thalamus, globus pallidus, and corpus striatum. Here's a good website that explains the location and functions of these regions.
Four "sets" of people were compared:
- Control Clean - No schizo/no drug use - 44 people
- Control CUD - Cannabis Use Disorder - 10 people
- Schizo Clean - Clinically diagnosed schizophrenic/No drug use - 28
- Schizo CUD - Schizophrenic with CUD - 15
CUD is defined as 80% or higher percentage of daily use.
Clinical mental functions were assessed using SCID.
Working Memory (WM) was assessed using 4 clinical WM tasks.
Limitations to the study:
Three subjects did not complete the WM assessments (1 CON-CUD, 1 SCZ-Clean, and 1 SCZ-CUD). Two subjects completed only 2 subtests and were not included when computing the WM domain score (1 SCZ-Clean and 1 SCZ-CUD). Twelve subjects missed a single WM item, and a group-level mean imputation replaced the missing item
So with an already small n-value, now we have participants only partially completing tasks...
Other limitations, as stated by the authors:
- Detection of shape differences, but not volume
- No quantitative measurement of cannabis use
- No pharmacological treatment data, other than antipsychotic meds
- 3 control CUD members had history of other drug abuse
RESULTS
- Cannabis use disorder may be associated with differences in working memory-related subcortical morphology in both control and schizophrenia subjects.
- More severe “cannabis-related” striatal and thalamic shape differences were associated with more marked deficits in WM in both control and schizophrenia subjects. These areas are associated with a high expression of CB1 receptors and mediation of working memory.
- Further, the observed patterns of neuromorphological differences in subjects who used cannabis were also consistent with the known distribution of CB1 receptor expression across various subcortical regions.
- An earlier age of CUD onset was associated with greater “cannabis-related” shape differences in both CUD groups.
- IMO, a very weird observation was that CON-CUD were characterized by outward shape differences in the nucleus accumbens, while SCZ-CUD were characterized by inward shape differences in this region.
Final authors note:
Although our data may be compatible with a causal hypothesis, the cross-sectional data do not allow us to test causal relationships or reject alternative explanations.
This article a continuation of some interesting research suggesting a link between schizophrenia and marijuana use. It demonstrates some interesting initial results and sets up a proof-of-concept for follow-up experiments. Evidence suggests a causal relationship between heavy marijuana use and subcortical brain morphology changes, but more experiments are needed to confirm, especially at the molecular level. In no way is this groundbreaking news, nor does it tell us anything particularly conclusive.