For patients with no history of substance abuse, ADHD medications, when taken at medically-recommended dosages, are usually no more addictive than caffeine.
For patients who do have substance abuse issues, ADHD treatment can be more problematic, and these patients are at increased risk for abuse and misuse of prescribed ADHD medications.
Patients with ADHD are twice as likely to have problems with substance abuse as those without ADHD. The reasons for this are numerous and vary for each person, and usually include genetic risk factors. It is also often the case that patients with ADHD are more impulsive in most regards, including with the ability to modulate substance usage.
Even when patients feel that their substance use is related to their ADHD, substance use disorders are best addressed and treated as problems in their own right; treatment of ADHD does not by itself reduce rates of substance abuse.
Some forms of substance abuse, particularly regular marijuana usage, can present with symptoms similar to ADHD. Chronic cannabis usage is associated with neurocognitive effects that include deficits in attention and working memory, slowed mental processing, difficulties with decision making and impulsivity. These deficits have been documented to last up to several months past the last time of marijuana usage. Some patients report that they use marijuana or other substances to self-medicate their attentional difficulties. Given what is known about the effects of cannabis on cognition, it is difficult to postulate a physiologic mechanism whereby marijuana could treat a primary attentional deficit.
For these reasons, the ongoing usage of substances, particularly marijuana or stimulants (such as methamphetamine or cocaine), makes it extremely difficult to achieve diagnostic clarity prior to beginning treatment. Those substances also make it challenging to assess the true benefits of a medication once ADHD treatment has been initiated, since ADHD medications have reduced benefits while there is ongoing substance use.
In all cases it is recommended that patients be off all substances of potential abuse before starting medication treatment for ADHD.
If you think you may have ADHD but are still using excessive alcohol, marijuana or other drugs, I would be glad to provide you with some referrals to help you try to address your substance use before trying to treat your attentional difficulties.
Here is one good source for further information: The California Society for Addiction Medicine
There is quite a large medical literature on this topic. I list some examples here for those interested in reading deeper into the topic:
Health Effects of Marijuana Usage. New England Journal of Medicine. 370;23. June 5, 2014
Neural correlates of performance monitoring in chronic cannabis users and cannabis-naive controls. Fridberg DJ, Skosnik PD, Hetrick WP, O’Donnell BF. Journal of Psychopharmacology. 2013 Feb 20.
Neuropsychological deficits associated with cannabis use in young adults. Grant JE, Chamberlain SR, et al. Drug and Alcohol Dependence. 2011 Sep 13.
Adolescent substance abuse: the effects of alcohol and marijuana on neuropsychological performance. Thoma RJ, Monnig MA, et al. Alcohol Clinical and Experimental Research. 2011 Jan;35(1)
Chronic cannabis users show altered neurophysiological functioning on Stroop task conflict resolution. Battisti RA, Roodenrys S, et al. Psychopharmacology. 2010 Dec;212(4):613-24.
Executive function deficits in short-term abstinent cannabis users. McHale S, Hunt N. Human Psychopharmacology. 2008 Jul;23(5)
The influence of marijuana use on neurocognitive functioning in adolescents. Schweinsburg AD, Brown SA, et al. Drug Abuse Reviews. 2008 Jan;1(1)
The relationship between non-acute adolescent cannabis use and cognition. Harvey MA, Sellman JD, et al. Drug and Alcohol Reviews. 2007 May;26(3)
Neuropsychological deficits in long-term frequent cannabis users. Messinis L, Kyprianidou A, et al. Neurology. 2006 Mar 14;66(5)
Attributes of long-term heavy cannabis users: a case-control study. Gruber AJ, Pope HG, et al. Psychological Medicine. 2003 Nov;33(8)