Smoking cannabis certainly escalates the risk of depression and anxiety, a new study has deduced.

U.S. researchers discovered the brains of users lost the ability to respond to dopamine – the feel-good chemical that kindle a spirit of get-up-and-go.

The study adds up to earlier research indicating marijuana can cause people to become withdrawn, lethargic and apathetic.
Psychiatrist Dr Nora Volkow, of the National Institute on Drug Abuse in the U.S., employed the stimulant Ritalin to discern the effect cannabis produced on the brain.

Like cocaine, Ritalin escalates levels of dopamine in the brain.This made it apt for the study, published in the journal Proceedings of the National Academy of Sciences.

In total 48 people participated in the study. 50% consumed the drug — and the rest acted as a control group.

Personality and brain scans indicated that cannabis consumers had markedly blunted dopamine responses versus the controls who never had the drug.

This could bring on drug-craving and negative emotions, an inclination towards depression and anxiety which are strong indicators of cannabis addiction.

Dr Volkow explained the phenomenon cannot be completly attributed to depletions in dopamine release.

They feel there is a downstream effect towards the end of the process in a section of the brain named the striatum – the reward and motivation region.

In fact, one year back a study from Imperial College London discovered that prolonged consumption of cannabis destroys dopamine.

Levels in the striatum – located to the side of the brain – were found to be lower in regular cannabis users.

Dr Michael Bloomfield, of Imperial College London, said: ‘Dopamine is involved in telling the brain when something exciting is about to happen – be it sex, drugs or rock ‘n roll.