In 2005, Canadian researchers made a groundbreaking discovery that would forever discredit the myth that marijuana causes brain damage. What they found was an opposite effect. That is, THC – the main chemical in marijuana and the reason why users get ‘high’ – can actually cause new brain cells to grow.
The process of brain growth is called neurogenesis and does not usually improve with drug use. Marijuana use is a different story, explained Xia Zhang, M.D, Ph.D., associate professor at the University of Saskatchewan and lead author of the study: “Most ‘drugs of abuse’ suppress neurogenesis. Only marijuana promotes neurogenesis.”
Still, THC is not the only chemical found in marijuana and, eight years later, a team from Brazil is giving marijuana users more reason to celebrate. Their study, published in the July issue of The International Journal of Neuropsychopharmacology, shows that cannabidiol (CBD) can help your brain grow too.
Looking to investigate the effects of CBD on anxiety and depression in rodents, the researchers went to the source – a part of the brain called the hippocampus. The hippocampus regulates emotion and cognitive function and is also the only area of the adult brain that can grow.The hippocampus plays a role in emotion, memory, and learning.
While previous studies have found CBD to have beneficial effects on anxiety and depression, the new study is the first to explain why. What the scientists found was that CBD, just like THC, also causes brain cells in the hippocampus to grow. This, they say, could explain why previous studies identified CBD as an effective treatment for mood disorders.
“Our results indicate that chronic CBD administration, by promoting neurogenesis, favours a similar anxiolytic response in stressed mice.”
Likewise, other studies have linked depression, anxiety and stress – and even problems with learning and memory – to a lack of adult neurogenesis. Although this can be brought on by frequent substance use (expect for marijuana), neurogenesis also slows down naturally as you age.
But now there is hope, says the team from Brazil. A new understanding of how the brain reacts to CBD, along with other compounds in marijuana, “opens the door for their use to manage psychiatric symptoms in disorders such as ageing, stress and neuroinﬂammation.”
The study was led by Ismael Galve-Roperh of the Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Universitario de Investigacion en Neuroquımica (IUIN) and Instituto Ramon y Cajal de Investigacion Sanitaria (IRYCIS)