Amsterdam - Occasional and moderate abuse of the drugs cannabis and ecstasy does not lead to long-term memory impairment or affect ability to concentrate, according to a study conducted at Utrecht University in the Netherlands.

The findings are contained in a doctoral thesis by Gerry Jager, who conducted her research in combination with the Academic Medical Centre in Amsterdam.

"Occasional use of ecstasy (an average of a total of two pills) or frequent cannabis use (several marijuana cigarettes a week over a period of an average of four years) does not lead to long-term abnormalities in memory or ability to concentrate, or related brain activity," Jager found.