Tobacco Marijuana consumption makes the brain shrink

Long-term effect: Gray matter in the brain shrinks by smoking

11/11/2014

Through years of regular smoking, certain parts of the brain can shrink. This was stated in a new US study. According to this, long-term marijuana consumption reduces gray matter.

Kiffen causes parts of the brain to shrink
A recent US study finds that long-term and regular marijuana use can shrink certain parts of the brain, while other areas become more active. According to a news agency dpa, the exact consequences depend on when the drug was first consumed and how long. The results of the study has now been published in the journal „Proceedings of the National Academy of Sciences“ („PNAS“) published.

Brain part responsible for emotions and impulses
It has been reported that magnetic resonance imaging (MRI) was used to record the brain, especially the orbitofrontal cortex. This part of the frontal lobe of the cerebral cortex is considered to be responsible for the control of emotions and impulses as well as so-called „reward center“ of the brain. There are a particularly large number of CB1 receptors in this area, to which THC (tetrahydrocannabinol), the main psychoactive constituent of the hemp plant, has an effect. For the study, researchers led by neuropsychologist Francesca M. Filbey of the University of Texas at Dallas examined 48 adults who had used marijuana at least four times a week in the previous six months. The comparison group was made up of 62 non-users who matched the first group in terms of age and sex distribution.

Essential component of the central nervous system
It was found that the volume of gray matter in the orbitofrontal cortex was much smaller among drug users than among non-users. The gray matter, which is an essential component of the central nervous system, forms in the brain above all the outer areas. As reported, a higher volume of gray matter is associated with higher intelligence levels, according to recent studies. However, in addition to the decreased gray matter, the researchers also found that in marijuana consumers, white matter had increased connectivity compared to non-users.

Positive effect on white matter
The white matter regulates the communicative exchange between the individual brain areas. It is composed of nerve fibers that connect individual brain regions. „Thus, cannabis may have a positive effect on the white matter in terms of regulation of mitochondrial activity, antioxidant processes, and the regulation of degradation processes that protect neurons at the molecular level.“ However, the increased connectivity is reduced again in long-lasting marijuana use. According to the study authors, the split development makes clear how complex the effects on the brain are.

Reduction of the intelligence quotient
How much regular killing harms the brain has already been shown in older studies. For example, scientists working with Madeline Meier from the Department of Psychology and Neuroscience at Duke University in Durhamn, USA, found in a long-term study years ago that cannabis is apparently irreversibly damaging the central nervous system and causing a reduction in the IQ (Intelligence Quotient). According to the study, negative effects became apparent, especially among consumers who started using drugs at an early age. (Ad)