Gateway drug effect

The gateway drug effect (alternatively, stepping-stone theory, escalation hypothesis, or progression hypothesis) is a comprehensive catchphrase for the often observed effect that the use of a psychoactive substance is coupled to an increased probability of the use of further substances. Possible reasons for the connection include environmental influence, impulsive people seeking both soft and hard drugs (meaning people who use one drug are likely to use another drug due to personality and that it's not the initial drug that leads to the use of another drug),^[1] alterations in the brain due to earlier substance exposure, as well as similar attitudes of people who use different substances, and therefore experience a "common liability to addiction".^[2] In 2020, the National Institute on Drug Abuse released a research report which supported allegations that marijuana is a "gateway"^[3] to more dangerous substance use; one of the peer-reviewed papers cited in the report claims that while "some studies have found that use of legal drugs or cannabis are not a requirement for the progression to other illicit drugs [...] most studies have supported the "gateway sequence"."^[4] However, a 2018 literature review conducted by the National Institute of Justice, which analyzed 23 peer-reviewed research studies, concluded "that existing statistical research and analysis relevant to the "gateway" hypothesis has produced mixed results",^[5] and that "no causal link between cannabis use and the use of other illicit drugs can be claimed at this time."^[5]