Whether it's the caffeine in your coffee, a medicine for a chronic condition or the use of a recreational drug like ecstasy, central nervous system stimulants all have potential risks and benefits. In the short term, stimulants generally increase alertness and exert physical effects such as constricting blood vessels and increasing heart rate. Different stimulants work in different ways, and they can be classified into 4 main groups accordingly: direct psychomotor stimulants, methylxanthines, nicotine and MDMA.
Cocaine, Amphetamines and Other Direct Psychomotor Stimulants
Direct psychomotor stimulants include cocaine, ephedrine, cathinone, amphetamine, methamphetamine and methylphenidate. These powerful stimulants induce a fight-or-flight state that is essentially the opposite of relaxation, with effects like increased heart rate and blood pressure. Parts of the brain involved in pleasure and arousal become activated, and a temporary sense of energy and euphoria follows, along with decreased appetite. Then comes the crash -- depression and tiredness, often accompanied by insomnia, anxiety and irritability. All psychomotor stimulants are addictive, and the risk of overdose is significant. If addiction takes hold, long-term effects can include mood disturbances, restlessness, paranoia and hallucinations.
Caffeine and Other Methylxanthines
Methylxanthines -- including caffeine, theophylline and theobromine -- are natural plant components that can be found in products like coffee, tea, cola and chocolate. Methylxanthines are also found in some medications that help breathing by opening the airways. They induce wakefulness and increase energy, but unlike the direct psychomotor stimulants, they do so by inhibiting brain processes that make you tired, rather than stimulating brain processes that make you feel energized. The result is a much milder stimulant effect with methylxanthines.
Nicotine, found naturally in tobacco, is traditionally thought of as a stimulant. Although nicotine activates brain pathways, leading to stimulant-like effects, it also reduces stress and anxiety. These actions in the brain are very different from those of the direct psychomotor stimulants and methylxanthines. Nicotine, however, is highly addictive, just like many of the stimulants. With addiction, continued exposure to toxic substances found in tobacco and its smoke affects nearly every organ, increasing the risk for cancer, lung disease, heart disease and stroke.
MDMA, or methylenedioxymethamphetamine, has properties that are similar to methamphetamine, but it also acts as a mild hallucinogen. Also known as ecstasy or Molly, MDMA has been associated with a unique emotional and social response, described as an increased sense of empathy and connection with others. Although some evidence supports a possible therapeutic use, significant health risks are associated with MDMA, including memory problems and hyperthermia -- a rare but very dangerous increase in body temperature.