Researchers explain the ‘amotivational syndrome’ in cannabis users
According to a study published in the journal Biological Psychiatry, cannabis leads to decreased motivation when consumed for a long time due to reduction of dopamine in the brain. It seems that researchers at Imperial College London, UCL and King’s College London, found that those who frequently consume cannabis or those who started using cannabis at a young age, have low levels of dopamine in the striatum (a subcortical part of the forebrain). This could be the explanation for the fact that cannabis is associated with a lack of motivation.
Although the study was done on a small number of patients (19 regular cannabis users and 19 non-users), the results showed low levels of dopamine in those who started consuming cannabis early. Using PET brain imaging, researchers were able to see how cannabis affects dopamine levels in the striatum. All cannabis users explained that, during smoking, they had experienced psychotic symptoms and strange sensations such as they had been threatened by an unknown force. Based on these data, researchers expected to find high levels of dopamine in these individuals, but the results showed that, on the contrary, dopamine levels were low.
First contact with cannabis (those included in the study) was between 12 and 18 years and it was found that those who started cannabis early, as well as those who consumed frequently, had lower levels of dopamine. The lowest levels of dopamine were found in those who met the criteria for dependence or abuse of cannabis, and this finding led researchers to think that dopamine levels may be a marker of addiction. Dr Michael Bloomfield, from the Institute of Clinical Sciences at Imperial, who led the study, said the results were not the ones they expected but they correlate with other studies that point out that substance abusers (cocaine, methamphetamine) have altered levels of dopamine. “It has been assumed that cannabis increases the risk of schizophrenia by inducing the same effects on the dopamine system that we see in schizophrenia, but this hasn’t been studied in active cannabis users until now,” said Dr. Bloomfield.
The effect of cannabis has been highlighted by other studies that have shown that people who consume this recreational drug have an increased risk of mental illnesses and episodes of psychosis (schizophrenia, for example). The first psychoactive effect of cannabis include euphoria and relaxation (caused by a compound called tetrahydrocannabinol), then it comes a state of introspection that can result in paranoia and anxiety.