Smoking pot just once might be linked to changes in young brains, a new study suggests.
Adolescents who smoked marijuana one or two times had increased amounts of gray matter – a combination of neuron bodies and cells that feed them – in brains compared with those who had not, according to a new study published yesterday (Jan. 14) in the Journal of Neuroscience.
A bigger brain volume may sound like a benefit to adolescents, but it may not be said lead study author Catherine Orr, a lecturer in the department of psychological sciences at Swinburne University of Technology in Australia. [7 Ways Marijuana May Affect the Brain]
That's because, in adolescence, the brain typically undergoes a process called pruning, Orr said. During this process, which goes on through a person's early 20s, the brain chips away from its existing gray matter, and increases the amount of white matter, which consists of the long tails of neurons called axons that connect cells, and their protective coating called myelin
Though it's not absolutely clear why the brain does this, the best explanation to date is that the brain is more efficient, cutting away unnecessary or redundant components, and also makes the brain more complex by building more connections, Orr said.
That's why interfering in the process ̵
Measuring gray matter
In their study, Orr and her team looked at brain scans from 46 teens , age 14, from Ireland, France, England and Germany. Some reported having smoked marijuana once or twice while others have never used the drug at all. The researchers controlled for other factors such as cigarette smoking and alcohol-use that could have also driven these changes.
The study found that those who smoked pot had higher volumes of gray matter in areas of the brain that had cannabinoid receptors, compared with those who reported never using the drug. Compounds in marijuana bond to cannabinoid receptors, which are found in areas including the amygdala (which is involved in emotion and threat processing), the hippocampus (which is involved in memory and learning), and the nucleus accumbens (which is involved in reward and learning). addiction).
The researchers also found that those who had increased gray matter in their brains also had lower perceptual reasoning and had a better ability to work with normal levels of gray matter
"I personally was surprised The results were found, "Previous studies had found marijuana affecting similar areas of the brain, however, these studies have had inconsistent results. For example, some studies in adults have found that marijuana-use was linked to an increase in gray matter, while others found the opposite. It is difficult to find the potential effects of other substances such as alcohol.
Even so, increasing evidence shows that adults use marijuana at higher rates or for longer amounts of time or time. those who started earlier in life showed greater changes in the brain, she said.
Still, said that more research is needed to say what the effects of marijuana are on the brain. The small sample size of the study makes it difficult to disentangle the effects that other activities may also have on the brain, she added.
It's also unclear whether these changes in the brain are long-loading, Or said, adding that it would be good to do a follow-up study to explore this question. Ultimately, the researchers hope to find out who people are at risk of these brain-based effects and [let] people know what [these effects] are, "Orr said.
Originally published on  Live Science