Long-term exposure to cannabis has never been demonstrated through statistically significant data to pose any risk of irreversible cognitive impairment in children and pre-pubescent adolescents or adults as data for these types of studies does not exist and rat models using synthetic cannabinoids are not translatable to human exposures nor demonstrable in current legal climates. Acute cannabis intoxication causes alterations in attention, psychomotor task ability, and short-term memory however a dose-response relationship has not been formally established through blinded randomized placebo controlled trials which represent the gold standard by which these factual relationships are determined. While structural changes have been shown, studies have not demonstrated causation between cannabinoids and functionally significant long-term central nervous system effects of the drug or negative changes to brain composition. Misrepresentation of data as demonstrating significance particularly regarding cannabinoids is a rampant issue in the scientific community and many of the studies that demonstrate brain structural changes have deluded confounding variables and selection bias that renders much of their data useless with which to draw meaningful conclusions. Acute intoxication is often misrepresented as long term cognitive effects however data has demonstrated that chronic cannabis exposure requires longer to "wash out" of users and thus the acute intoxication affects appear to persist. Adequate time for wearing off produces data that demonstrates no difference in users performance of cognitive tasks.
In large enough doses, THC can induce auditory and visual hallucinations. Acute effects while under the influence can include both euphoria and anxiety.Cannabidiol (CBD), another cannabinoid found in cannabis in varying amounts, has been shown to alleviate the adverse effects of THC that some consumers experience.
Research about medical benefits of cannabis has been hindered by United States federal law. Smoking any substance will carry the same risk as smoking marijuana due to carcinogens in all smoke, and the ultimate conclusions on these factors are disputed.
... have got me worried about the long-term health implications of dope. I'm a 39-year-old woman and recently have had quite unpleasant bouts of anxiety and insomnia - might this be caused by my smoking? Can you have a delayed reaction, and are there any other long-term effects?.
But this does not remove all doubt over the harmful effects of prolonged cannabis use. A recent study by the National Institute on Drug Abuse in the United States found that the long-term effects of cannabis included the destruction of nerve cells in the hippocampus - the part of the brain that is crucial for learning and memory.