Cannabis may hold a novel treatment for depression

The World Health Organisation recently declared that depression would be the world’s number one disabling affliction by 2030. Currently, nearly 20% of all US citizens will suffer clinical depression in their lifetime. Although multiple lines of treatment for depression exist, the majority of people who experience one depressive episode will unfortunately experience another subsequently. The hunt for novel treatments which can be tailored to a patient’s needs is on. For the last decade, research into the cannabinoid system has been prolific. Components of this neurotransmitter system, first scientifically explored thanks to the effect cannabis has on the brain, are expressed almost ubiquitously in the central nervous system. In fact, there are more cannabinoid 1 (CB1) receptors than serotonin, dopamine and noradrenaline receptors combined. Importantly, many CB1 receptors are found in areas of the brain associated with mood processing, such as the amygdala and prefrontral cortex. Hence, the activation of these receptors can influence emotional processing and mood in animals and humans. A vast array of animal studies investigating how manipulation of the cannabinoid system might lead to changes in mood has taken place. For instance, compounds such as THC and CBD, which act on the cannabinoid system, have been shown to reduce depression symptoms as measured by specific tasks that model depression in animals. Furthermore, chemicals that exclusively block CB1 receptor activation have the opposite effect, increasing anxious and depressive behaviour. These same drugs were trialled in humans to try and suppress hunger in obese people. Unfortunately, they had extremely unpleasant side-effects with many participants describing sadness and anxiety. It therefore seems, in a simple sense, that by decreasing the activity of the cannabinoid system, depressive symptoms emerge, and by increasing the activity, the opposite happens. Accordingly, 2011 and 2012 reviews of the cannabinoid data are calling for clinical studies to take place, so that manipulation of the cannabinoid system can become one of the potential options when treating depression. This is not to say that doctors will soon be prescribing stinking bags of dope to sufferers of depression, but that the scene is set for research into how THC, CBD and other related compounds may one day help sufferers.