EVIDENZE DALLE NEUROSCIENZE SUGLI EFFETTI DELL’USO DI CANNABIS E POSSIBILI CONSEGUENZE DELLA LEGALIZZAZIONE SULLA SALUTE PUBBLICA

Background: The discussion on the legalization of cannabis has assumed great resonance because of some American States, which, after legalizing the use for medical purposes 15 years ago, now have al-so authorized the use for recreational purposes. In Italy, in July 2015, some politicians submitted a leg-islative proposal advancing the legalization of cannabis for medical and recreational use. Objective: To make an examination of scientific evidences on the effects of cannabis use and an analysis of the possible impact of cannabis legalization on public health, in the light of US experience. Methodology: For the scientific evidences on the effects of cannabis on the human organism, we looked at the main literature of the last 15 years, coming from disciplines such as neuroscience of ad-diction, toxicology, behavioral science, genetics, psychiatry, etc. To assess the impact of legalization in the US, we took into account government reports, data from state and federal institutional investiga-tions and ad hoc surveys. Finally, we made a synopsis of the main positions in favor of legalization, in comparison with scientific evidences and other alternative positions. Results: Results of the main scientific researches confirmed that cannabis use is associated with struc-tural brain abnormalities of gray and white matter, impairment of cognitive functions, psychotic disor-ders, amotivational crisis, addiction, etc. There are consequences on organ systems, including respira-tory and heart diseases and impairment of the reproductive and immune systems. The influence on DNA damage and the resulting human epigenome impairment has also been highlighted. These nega-tive conditions are the more severe the earlier the substance onset. At social level, many issues related to the use of cannabis have been registered: drug-related road accidents, accidents at work, poor school performance and increased risk of criminal behavior. Several data have been collected from US States where cannabis has been legalized. Although data should be considered preliminary, the analysis showed: • An increase in cannabis consumption in all age groups considered, in particular in the range 18-26 years, where there has also been an increase in alcohol consumption; • An increase in acute poisonings registered at ED and increased hospitalizations in relation to can-nabis-intake; • An increase in THC positivity in road accidents and increase in the n. of cannabis-related road deaths; • An increase in the prevalence of THC positivity in workplace drug testing; • An increase in school dropout rate; • An increase in juvenile arrests for illegal possession and use of cannabis; • An increase in illegal trafficking of cannabis from the State that legalized its cultivation and con-sumption, towards neighboring States that have not legalized it; • An increase in tax revenue. However, revenues do not appear to have been allocated for preven-tion, treatment and research, as originally scheduled. Conclusion: Epidemiological data, combined with scientific neuroscience evidence, provide evidence based elements useful for the legislator to guide the future legislation in Italy. It is desirable that the lawmaker takes in greater account scientific evidences, especially from neuroscience, toxicology, be-havioral sciences and mental health. It is necessary that the legislator consider not only the economic and financial aspects of legalization, but also the health impact in the medium and long term.