International study finds young teenage pot users risk IQ loss

This widely publicised study found that younger teenagers who regularly use marijuana could face a significant drop in their IQ. Over 1,000 New Zealand children were tested at 13 and then 38 years of age and regularly interviewed. Those classed as dependent suffered an average 8 point drop in IQ, even if they later quit. Those who became dependent after 18 years did not suffer the same decline. Although the findings are not definitive they highlight the importance of this field of research.

Links:

• Teen pot use linked to later declines in IQ - Associated Press

• NIH-funded study links long-term marijuana use, especially when started during adolescence, with decreased IQ and impaired cognitive function - NIDA

• Persistent cannabis users show neuropsychological decline from childhood to midlife - Abstract via PNAS