Researchers in Norway have rejected the theory that heavy cannabis use during teenage years may lower the intelligence of a person.
A study conducted by New Zealand researchers last year found that regular use of cannabis before 18 years of age reduced the IQ of the user. However an analysis of the study conducted by economist and researcher Dr Ole Rogeberg in Norway revealed that the link between lowered IQ and cannabis use found in the study can be explained by socio-economic factors.
However his findings were questioned by Professor Richie Poulton from Otago University who was part of the original study. Professor Poulton said that while the IQs of the participants did increase when they went to schools, it dropped back to its former mark when they dropped out. Professor Poulton added that while Dr Rogeberg's findings were based on simulations, the study's findings came from real data.
"Many of the adolescent cannabis users in the [New Zealand] study were from slightly lower socio-economic homes, though not all. However, their IQs were not boosted by schooling, because their IQ scores are the same from the time they began school to adolescence", he said.