Posting this antidote to magical thinking to stoke the indignation of the Web’s marijuana fan club. Always entertaining.
About 9% of adults who use marijuana develop an addiction to it. Among people who begin smoking before the age of 18, this number is as high as 17%. Although addiction to marijuana does not cause dramatic physical dependence, it can lead to substantial problems in education, work and relationships. In fact, addiction to marijuana is defined by the inability to stop using despite recognition of harmful consequences. Without harmful consequences, there is no diagnosis of addiction.
The short-term effects of marijuana intoxication are well established. As part of the high produced by marijuana, intoxication impairs memory and learning. Marijuana use also impairs driving, causing a twofold to threefold increase in accidents. Though not as dramatic as the fifteenfold increase in accidents caused by alcohol intoxication, marijuana’s impact on traffic safety does have significance.
The long-term effects of marijuana are not often recognized because they are subtle, but they can have a cumulative impact over time. In people with preexisting vulnerabilities, marijuana use can unmask psychiatric problems such as schizophrenia. Many people with anxiety and depression use marijuana to soothe their symptoms; however, there is evidence that over time it may actually make these problems worse.