Recent research sponsored by the medical group Northwest at Harvard University medicine using functional MRI scanners, to analyse the brains of young cannabis users, has shown that there is a marked increase in abnormal alterations in the brain.  Previous longitudinal ( long  term)  study  carried out in Sweden shown that regular cannabis use in young adults can affect the brain’s ability to produce the “reward chemical” dopamine, which is usually secreted in the brain during pleasurable experiences such as eating, social interaction and sex.  The Harvard University study carried out using a sample of 40 people aged between 80 and 25.Using state-of-the-art neuro-imaging techniques to analyse the brains of the research participants showed that an area in the brain called the nucleus ascumbens is unusually large in cannabis users.  While the amygdala, has notable abnormalities.  One has to take into consideration that the amygdala is often thought, as the centre of all emotions. The researchers unclear as to how these abnormalities will affect younger people, but in a 2013 longitudinal study in Sweden showed that there is a conclusive causal link between cannabis use and psychosis.  One has to bear in mind that hydroponically and selectively grown plants are now eight times stronger than the block marijuana use by the flower power generation in the 60s.  One striking fact is that whilst this study is taking place, states in the US are considering legalising cannabis use, with Colorado leading the way.  One has to ask, how long is it before legalise cannabis use is on the statute books in the UK.