View Full Version : What does this study suggest?


CBDialog
01-05-15, 01:17 AM
From what I understand this study is showing that stimulants seem to cause changes in the basal ganglia. But that doesn't mean the changes are good. Right?

http://www.ncbi.nlm.nih.gov/pubmed/20595414

namazu
01-05-15, 02:02 AM
No, changes (or larger vs. smaller) aren't uniformly good.


In this study, the authors report the following:
Effects of Stimulant Use

Within the ADHD group, analysis of conventional volumes in those treated with stimulant medication and those untreated did not discern significant effects of stimulant medication (main effects of stimulant use F41= 0.20; p=.67; stimulant use-by-nucleus interaction F90= 2.21; p=0.12). Volumes of the caudate (3681.0 ± 92 vs 3642.6 ± 129 mm3; p=0.63), putamen (4989.1 ± 101 vs 4838.1 ± 142 mm3; p=0.21), and globus pallidus (1728.3 ± 32 vs 1671 ± 45 mm3; p=0.51) did not differ significantly between those in the ADHD group on stimulants compared to those off stimulants. Surface analyses, however, revealed significant, localized outward deformations of the basal ganglia surface in the youth with ADHD treated with stimulants compared to those with untreated ADHD (Fig. 2). In addition, we detected a statistical attenuation of the main effect of diagnosis when comparing the control group to individuals in the ADHD group treated with stimulants (Fig. 2), whereas we detected a strengthening of the statistical significance of diagnosis when comparing to the control group those in the ADHD group who were untreated with stimulants (Fig. 2). These findings demonstrate the presence of exacerbated inward deformations of the basal ganglia surface in untreated compared with treated youth with ADHD.

Volume-wise, it sounds like there wasn't much detectable difference between the medicated ADHD youth and the unmedicated ADHD youth in any of the brain structures the researchers studied.

However, comparing structures on the surface of the basal ganglia, there were some differences. ADHD youth (both medicated and unmedicated) had more "inward deformations" than non-ADHD youth -- and the severity of ADHD was associated with the degree of inward deformation (more severe ADHD, greater inward deformation).

However, the ADHD youth who had taken medications had basal ganglia surfaces that appeared closer to "normal" brains than the unmedicated ADHD youth.

The authors conclude:
These findings potentially represent evidence of anatomical dysregulation in the circuitry of the basal ganglia of children with ADHD and suggest that stimulants may “normalize” morphological features of the basal ganglia in children with ADHD.

So they're suggesting that the brains of youth with ADHD are shaped a bit different from brains of typically-developing youth (especially in those with more severe ADHD and those who have not taken medications), but stimulants are associated with more "normal-looking" basal ganglia surface anatomy.

mildadhd
01-05-15, 02:59 PM
Surface analyses, however, revealed significant, localized outward deformations of the basal ganglia surface in the youth with ADHD treated with stimulants compared to those with untreated ADHD

BG no deformations (do not have ADHD)

BG inward deformations (ADHD not treated with medication)

BG inward deformations and outward deformations (ADHD treated with medication)



Maybe BG inward deformations are a result of having ADHD?

Maybe BG outward deformations are a result of BG tolerance to ADHD medication?




P

mildadhd
01-05-15, 10:50 PM
The scientists also found that parts of the brain reward system where cocaine exerts its actions (the basal ganglia) were significantly enlarged in cocaine users; but the size of the enlargement was not related to the duration of cocaine use.

The researchers believe this may suggest that alterations in the brain’s reward system predate cocaine abuse, possibly rendering these individuals more vulnerable to the effects of the drug.

- See more at: http://www.cam.ac.uk/research/news/abnormal-brain-structure-linked-to-chronic-cocaine-abuse#.dpuf


This article suggests that chronic cocaine use also "enlarges" areas of the basal ganglia.

And also that alterations in dopaminergic pathways prior cocaine use, may result in some people being more vulnerable to getting addicted to cocaine.





P

namazu
01-05-15, 11:30 PM
This article suggests that chronic cocaine use also "enlarges" areas of the basal ganglia.

And also that alterations in dopaminergic pathways prior cocaine use, may result some people being more vulnerable to getting addicted to cocaine.

It sounds like the chronic cocaine users had larger basal ganglia (BG) on average than non-users.

But the researchers suspect that it may not have been the cocaine that caused the enlargement. In the cocaine-using group, the researcher did not observe a link between basal ganglia size and intensity of cocaine use, which they expected if the cocaine were actually causing the enlargement.

(I'm not sure that's a good assumption, by the way. A pattern like that would be suggestive, but not a clincher.)

On the other hand, heavier / longer-term cocaine users had less gray matter than lighter / shorter-term cocaine users.

This study didn't look at the participants' brains over time, so they really couldn't determine which came first (BG enlargement, or cocaine use).

As you pointed out, some of the brain differences may predispose people to cocaine use, rather than the other way around.

Given the overlap of ADHD and substance abuse problems, sorting out these "chicken and egg" questions -- and probably feedback loops, too, just to keep things challenging! -- would be really useful.

mildadhd
01-06-15, 12:40 AM
I was thinking the researchers associated chronic cocaine use with the enlargement of the basal ganglia, but not only "related to the duration of cocaine use."

And that there are also other previous factors involving the development of the dopaminergic pathways that might be making continued cocaine use more attractive.

I am not sure if my interpretations are in the right ball park, but I am learning a lot from the discussion.


Thanks


P