ADHD+and+Substance+Use

= [| ADHD and Substance Use]  =

ADHD has historically been a disorder surrounded by controversy. It has been known by several different names, people h ave questioned whether it is a real diagnosis, and some have viewed it as a condition that can only affect children (Baron & Bizamcer 2004). However, scientific inquiry around ADHD has recently shifted to include an acceptance of ADHD as a lifelong disorder, as well as a disorder surrounded by co-morbidities (Antshel, Faraone, & Kunwar 2008). Generally, it seems that co-morbidities are the rule rather than the exception, as ADHD is associated with high risk of learning disabilities, conduct disorders, mood disorders, anxiety disorders, and substance use disorders throughout the life span (Baron & Bizamcer, 2004).

There has recently been a dramatic increase in research regarding substance use among individuals with ADHD. Substance use disorders with an early age of onset are of particular concern as they are associated with significant social costs throughout the individual’s life or period of use. Recent research has shown that ADHD alone, and in combination with co-morbid psychopathologies such as conduct disorder, is a risk factor for the development of substance use disorders (FDA consumer, 2003). In fact, a study conducted by Molina and Pelham showed that teens diagnosed with ADHD reported episodes of drunkenness at a rate two times that of a non-ADHD control group. While both groups had similar responses when asked if they had ever tried alcohol, cigarettes or marijuana, the teens diagnosed with ADHD were three times more likely to have tried an illegal drug other than marijuana; individuals with ADHD were also more likely to have used two or more different types of illegal drugs than the control group (FDA Consumer, 2003). In a study conducted by Wilens et al., published in 1997, it was also found that girls with ADHD had an earlier age of onset of substance use disorders than their male counterparts, with a difference in age of onset of almost two years between the sexes (Wilens et al., 1997). The general trend in research around concurrent ADHD and substance abuse is congruent with the results of this study, showing that children with ADHD have a greater risk of substance use, with an earlier age of onset and a heavier pattern of use than non-ADHD controls. Interestingly, while ADHD is clearly linked with substance use, the disorder does not predispose the individual toward the use of a certain type of substance, although increased use of cocaine has been noted through anecdotal reports (Baron & Bizamcer 2004).

This trend of an increased rate substance abuse among individuals with ADHD does not only apply to adolescents. Elevated rates of substance abuse and dependence have also been consistently reported in adults with ADHD. In fact, it is estimated that 17-45% of adults diagnosed with ADHD have a history of either alcohol abuse or alcohol dependence. In comparison, 9-30% of the adult ADHD population has a history of drug abuse or dependence (Wilens, 2004). Furthermore, compared with non-ADHD controls, adults with comorbid ADHD and substance dependence display a greater severity of substance abuse with an earlier age of onset (Carrol & Rounsaville, 1993). When the lens is switched and researchers look at ADHD among substance users, an interesting trend emerges. Research indicates that ADHD is more prevalent among substance users than in the general population; prevalence rates of ADHD among substance users range from 15-25% (Spencer et al., 1998)

While the relationship between ADHD and substance use disorders is clear, the factors linking or underlying the connection between these two disorders have not yet been definitively elucidated. There are several theories that attempt to explain the link between ADHD and substance use disorders; one theory that is well known in the scientific community is the “Self-Medicating Hypothesis”. The “Self-Medicating Hypothesis” proposed originally by Khantzian suggests that individuals are predisposed to addictive disorders as a result of their psychiatric disturbances (Plume, 2006). Khantzian believed that an individual’s choice of drug was influenced by an interaction between their psychological state and the psychopharmacological effects of the drug they most liked using. Khantzian, working from a psychodynamic perspective, suggested that drug use would compensate for a defective or non-existent ego mechanism of defense (Plume, 2006). More recently, researchers have come up with a cocaine-specific “Self-Medicating Hypothesis”. According to this line of thinking, cocaine is used to help alleviate fatigue, to overcome depression, to decrease boredom, to increase self-esteem, and to alleviate impulsive or hyperactive affect states (Plume, 2006). Thus, it is thought that individuals with ADHD may be using cocaine to compensate for their ADHD problems (Alcoholism and Drug Use Weekly, 2007). The “Cocaine Self-Medicating Hypothesis” is supported by the high prevalence of cocaine addicts with ADHD (Alcoholism and Drug Abuse Weekly, 2007). The results of a recent study conducted by Whalen et al. are also congruent with the Self-Medicating Hypothesis, but are generalized to substances other than cocaine. In this study, one hundred fifty-three adolescents with low, medium, or high levels of ADHD characteristics were examined. Participants logged their behaviors, moods, and social contexts twice each hour across two 4-day periods. The results showed that those with high levels of ADHD characteristics, in contrast to those with low levels, recorded more negative moods and fewer positive moods and more tobacco and alcohol use (Whalen et al, 2002). Recently, there has also been a study that suggests that the link between ADHD and substance use may have biological underpinnings. The study examined dopamine levels in adults with ADHD versus a non-ADHD control group, in order to ascertain if dopamine levels are lower in the ADHD population, and if so, if this deficit results in inattention. The Dopamine System is often referred to as the ‘Pleasure Pathway’ in the brain, as it is very sensitive to the effects of psychoactive substances. Stimulants increase Dopamine levels in the brain by blocking dopamine transporters (Alcoholism & Drug Abuse 2007). The study, conducted by Volkow at the National Insitute on Mental Health used PET scans to show that adults with ADHD have a weaker response to ADHD medication Ritalin, (i.e. smaller increases dopamine levels in the brain) than a non-ADHD control group. This attenuated response on behalf of the ADHD group was linked with inattention and a greater enjoyment of the effects of the drug, suggesting both ADHD and substance use are linked and mediated via abnormalities in dopamine pathways (Alcoholism and Drug Abuse Weekly, 2007).

Finally, some researchers propose that the link between ADHD and Substance Use Disorders is mediated by psychological or environmental factors. Molina et al examined the association between the combined effects parental alcoholism and offspring with ADHD within a family, on substance use. This study suggested that higher levels of stress in these families contribute to higher rates of drinking in parents; also, the teens with ADHD have inefficient or a lack of coping skills that can result in their own heavy drinking behaviors (Mental Health Weekly, 2007). In another studied conducted in 2001, examining the link between ADHD, learning disorders and substance use, Molina and Pelham found children with higher IQs and higher levels of academic achievement in childhood were more likely to try cigarettes, to smoke daily and to have their first drink of alcohol or first cigarette at an early age. In this case the authors suggested that a pathway may exist for “at-risk” children, in which a higher intellectual capacity and performance lead to earlier experimentation with adult behaviors such as smoking and alcohol use. The authors also suggested that as a function of peer relationship difficulties experienced by children with ADHD, smoking was used to identify with peers (Molina & Pelham, 2001). Finally, others believe that conduct disorder, a common comorbidity with ADHD mediates between ADHD and substance use, as conduct disorder leads to a greater risk of early substance use over and above the risk associated with ADHD; however, the exact mechanism here has not been identified.

With the vast majority of research validating a link between ADHD and substance use, there has been recent concern regarding the use of ADHD medications such as Ritalin to treat young children; it is thought that exposing children to stimulants at a young age may in increase the risk of later illicit drug use, including stimulants such as cocaine. In order to examine the possibility of a link between the treatment of ADHD with stimulants early in life and later substance use disorder, Wilens et al,. conducted a longitudinal, case controlled study at the Massachusetts General Hospital in Boston (Wilens et al., 2008). One hundred and fourteen adolescents with ADHD were recruited, ninety-four o whom were treated with stimulants. All risk factors outside of stimulant treatment were controlled for, other than a family history of ADHD. After a five year follow-up, the authors found that those treated with stimulants were NOT at an increased risk for the later development of ANY substance use disorder, including cigarette smoking. In fact, that authors found early stimulant treatment actually had protective effects, as stimulant treated adolescents were 73% less likely to manifest a substance use disorder at follow-up than those who had not been treated with stimulants (Figure 1). Those treated with stimulant medications also had a 72% lower risk, and later onset of cigarette smoking relative to those who were not treated with stimulant medications (Figure 2). No significant association was discovered between age at onset or length of stimulant treatment and later risk of substance use disorder or cigarette smoking.



 Although this study presents a very clear connection between stimulant treatment and a decreased risk of later substance use disorders, the results may be limited by a small sample size in the non-treatment control group, and the lack of a randomized design What Wilens et al., were able to find through an earlier literature review, was that the protective effect of childhood or adolescent stimulant treatment tends to 'wear off' having only neutral effects on adults with ADHD (Wilens et al., 2003). Also, through this specific study, the authors were not able to elucidate the underlying mechanism through which early stimulant use decreases the risk of later substance use (Wilens et al., 2008).

However, a study conducted by Augustyniak et al in which rats were exposed to methylphenidate during the pubertal period suggests early exposure to Ritalin may diminish sensitivity to the incentive effects of cocaine in adulthood. The exact mechanism here is also not known, but the authors did ascertain that no permanent changes occurred in the rats' mesolimbic response to cocaine (Augustyniak et al., 2005). Wilens suggests psychosocial explanations must also be considered; it is possible that those individuals who showed a decreased risk of substance use disorders may be parts of families that sought out appropriate AHDH treatment, or that children who were administered stimulants for the treatment of ADHD were supervised more closely by their parents or guardians, decreasing the risk of the development of substance use disorders (Wilens et al., 2008).

Overall, it seems that although individuals with ADHD may be at an increased risk of developing substance use disorders in general, early treatment with stimulant medications does not appear to be a causal factor. Instead, stimulant medications appear to have a protective effect when it comes to the later development of substance use disorders or cigarette smoking.