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Research from the University of Warwick shows that there is a link between cannabis use and mania Reuters

There is a 'significant' link between the onset and exacerbation of mania symptoms and cannabis use, a leading institution has claimed.

Cannabis has typically been associated with the onset of depression but research from the University of Warwick shows that it is also heavily linked to mania – symptoms of which include prolonged states of elatedness, difficulty to sleep and hyperactivity, but it can also make sufferers experience bouts of aggression.

Dr Steven Marwaha, author of the study published in the Journal of Affective Disorders, said: "Previously it has been unclear whether cannabis use predates manic episodes. We wanted to answer two questions - does cannabis use lead to increased occurrence of mania symptoms or manic episodes in individuals with pre-existing bipolar disorder?

"But also, does cannabis use increase the risk of onset of mania symptoms in those without pre-existing bipolar disorder?

"The observed tendency for cannabis use to precede or coincide with rather than follow mania symptoms, and the more specific association between cannabis use and new onset manic symptoms, suggests potential causal influences from cannabis use to the development of mania. It is a significant link.

"Our review suggests that cannabis use is a major clinical problem occurring early in the evolving course of bipolar disorder."

Cannabis is the most common drug used among people under the age of 18 when the brain is at a critical stage of development, and Marwaha added that this could lead to manic episodes later in life.