Stimulants, sometimes referred to as pschyoactive drugs, temporarily induce increased physical or mental function. They are frequently referred to as "speed" or "uppers". Stimulants to the central nervous system include a broad category of substances such as amphetamines, methamphetamine (commonly called ice or crystal meth), cocaine, caffeine, nicotine, and some herbal extracts. The availability of stimulants is through therapeutic prescriptions, over the counter (OTC) medications such as decongestants, or through illicit means for recreational abuse. Stimulants are classified by the US Drug Enforcement Agency (DEA) as controlled substances. Historically, stimulants were used to treat asthma and other respiratory problems, obesity, neurological disorders, and a variety of ailments. However, as their potential for abuse and addition became apparent, medical use decreased to the limited treatment of narcolepsy, attention-deficit disorder and hyperactivity (ADHD), and as appetite suppressants (NIDA, 2008). Stimulants, such as dextroamphetamine (Dexedrine and Adderal) and methylphenidate (Ritalin and Concerta), cause the release of neurotransmitters (norepinephrine and dopamine, and serotonin). These medications are commonly prescribed to treat ADHD in children by stimulating the areas of the brain that control impulses and attention, producing a calming effect on their behavior. Tolerance is not seen in children with ADHD. The calming effect of stimulants is not effective on children who do not have ADHD. Amphetamines are also used to treat narcolepsy in adults. Dosages vary due to the development of tolerance to the stimulants.

Methamphetamine, is highly addictive and causes psychotic behavior and brain damage due to the substances used to make it (Videbeck, 2004). Some stimulants that are used as appetite suppressants or weight control agents are different in structure but behave like amphetamine. Some examples include Adipex, Fastin, Ionamin, Didrex, Phendride, T-Diet, Teramine, Zantryl, Sanorex, Mazanor, Plegine Plelu-2, & Tenuate. Several over-the-counter medications such as Sudafed, Drixoral, and Triaminic preparations contain pseudoephedrine which also acts as a stimulant. Caffeine, the most common stimulant, is naturally found in coffee, tea and cocoa or chocolate. It is added to soft drinks, particularly energy drinks and some medications to enhance the effect. Cocaine, a white crystalline powder, is made from the coca leaves mainly in South American countries. Cocaine is used recreationally as a stimulant and its abuse potential is high. Therapeutically, it is used as a local anesthetic for eye and ENT surgery and is strictly controlled. Herbal stimulants, kola, damiana, Asiatic and Siberian ginseng, and gotu kola, have been used to reduce muscle tension and stresses associated with drug cravings. Ephedra, an herbal stimulant was marketed as a dietary supplement for weight loss, energy enhancement and body building purposes. However, it has been associated with death, causing heart attacks and stroke, by increasing pulse and blood pressure (Videbeck, 2004). It has been taken off the market in the US due to serious health concerns. Nicotine, the primary ingredient in tobacco products, acts directly on the brain causing an increase in heart rate and respirations and causes more glucose to be released into the blood. Studies show that this is why smokers feel more alert after smoking a cigarette. Nicotine also triggers release of dopamine in the brain's pleasure and reward circuit, giving the smoker intense feelings of pleasure. These effects last for approximately 40 minutes, urging the smoker to light another cigarette to get another dose of nicotine. This craving is what makes nicotine so addictive (http://teens.drugabuse.gov/facts/facts_nicotine2.php). For more information see Nicotine. The CNS effects of stimulants include alertness, with a sense of wellbeing and euphoria. The heightened sense increased energy and decreased fatigue can cause a psychological habituation to the drug. Many users experience insomnia and anorexia (loss of appetite) and some may develop psychotic behaviors. Stimulants increase the heart rate and blood pressure and cause dilation of pupils. Adverse symptoms include chest pain, nausea, abdominal pain, and headaches. Long term use may cause in tolerance, weight loss and adverse psychiatric symptoms such as irritability, aggression, impulsivity, hallucinations and delusions. Signs of stimulant toxicity include a tense attitude, agitation or restlessness, talkative nature, altered thought processes that may include flight of ideas, paranoia, grandiosity, impaired judgment, confusion, and delirium. Memory is affected depending on length of use as small doses may increase memory. Heavy use/abuse can lead to coma. (Divadeenam, 2008). Withdrawal from stimulants presents with the symptoms of sedated behavior, depression or irritability, suicidal ideation and drug craving. There is a potential for homicidal tendencies as well as paranoia. There is no antidote for stimulant intoxication, but medication may be necessary for treatment of hypertension, agitation, and hyperthermia. As drugs of abuse, CNS stimulants produce a sense of exhilaration, improved mental and physical performance, increased confidence, or are used to "get high" (Videbeck, 2004). The potential for abuse is high and drug dependence develops after prolonged periods of use. Due to the rapid development of tolerance requiring increases in doses, dependence is common (Herfindal & Gourley, 1996).

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