Stimulants are a class of drugs that increase brain activity, producing gains in alertness, attention, and overall arousal, accompanied by elevations in blood pressure and heart rate. The most widely used stimulant in the world is caffeine, followed closely by nicotine. Stimulant drugs have been prescribed for a wide variety of problems, including asthma, obesity (as an appetite suppressant), and a range of other disorders, including narcolepsy, attention-deﬁcit/hyperactivity disorder, and even depression.
Most prescription stimulants belong to the category known as amphetamines, including dextroamphetamine (Dexedrine) and methylphenidate (Ritalin and Concerta are the best-known brands). In the world of illegal stimulants, methamphetamine (also called crystal meth) and cocaine are the most popular. All work by mimicking the action of the neurotransmitters known as monoamines, especially norepinephrine and dopamine, and by preventing reuptake (the process by which excess neurotransmitter molecules are reabsorbed into the neurons until they are needed again). In addition to the basic stimulant effect of increasing central nervous system (CNS) arousal and increasing blood pressure and heart rate, the elevation of dopamine levels is associated with a sense of euphoria— cocaine is especially good at this.
Stimulants are not associated with physical dependence and withdrawal to the same degree as opioids and depressants, but they can produce psychological dependence very quickly. In addition to the good feelings produced by the elevated dopamine levels, stimulants can also produce feelings of hostility and paranoia (the brain areas associated with these feelings are also stimulated). High doses of stimulants are also associated with heart arrhythmias and elevated body temperature, in addition to the obvious risks associated with elevated blood pressure.
Because of these well-established risks, stimulants are not prescribed very often anymore, with one odd exception: most stimulant prescriptions written today are for children with a diagnosis of attention-deﬁcit/hyperactivity disorder (ADHD). Most of these are for methylphenidate, but prescriptions for stronger amphetamines, including Dexedrine and Adderall, are rising steadily for children whose ADHD hasn’t responded well to methylphenidate. This is a curious development, since all of the side effects produced by amphetamines in adults are also potentially problematic for children. Other treatments for ADHD are effective, especially behavioral treatments, but they are expensive and time-consuming to implement.
Since stimulants work for about two-thirds of children with ADHD and are much easier and cheaper to use, they have become overwhelmingly popular, to the point that ADHD is probably being overdiagnosed in this country. This is supported by recent ﬁgures comparing U.S. consumption of stimulants to that of other countries. As of 1998, for example, the United States was consuming more than 350 million single doses of methylphenidate a year, as compared to less than 100 million in the rest of the world combined. It should be noted additionally that in the same year, about 40 percent of all methylphenidate prescriptions were written for children between three and nine years of age, with over 4,000 written for children two years of age or younger. This is important because the safety and efﬁcacy of the drug has not been established for children under the age of six, nor has the Food and Drug Administration (FDA) approved it. Because of its addiction potential, methylphenidate is listed by the U.S. Drug Enforcement Agency (DEA) as a controlled substance, and a thriving black market in methylphenidate has sprung up in many cities, as it has effects virtually identical to those of cocaine when similar quantities are consumed.
- MTA Cooperative Group. “National Institute of Mental Health Multimodal Treatment Study of ADHD Follow-Up: 24-Month Outcomes of Treatment Strategies for Attention-Deﬁcit/Hyperactivity Disorder.” Pediatrics, 113(4) (2004): 754–762.