Strong cannabis causes one in four cases of psychosis

Strong cannabis causes one in four cases of psychosis | Daily Mail Online:

Strong cannabis causes one in four cases of psychosis: 
Users three times more likely to have an episode than those who have never tried it

• Scientists at King’s College London say youngsters must be told of risks
• Study will add weight to calls for a tougher stance on cannabis users
• More than 1 million 16-24-year-olds in England and Wales smoke the drug
• Those who use weaker 'hash' over potent 'skunk' less affected by episodes