Cocaine’s Psychostimulant Effects
The intensity of cocaine’s impact on the central nervous system depends largely on dose. At low doses, cocaine’s effects are fairly similar to those of caffeine: it combats drowsiness and fatigue, increases energy and alertness, and enhances mental acuity.[20] With increasing doses, most users begin to experience negative effects such as nervousness, jitteriness, sleeplessness, and agitation and at very high doses, feelings of suspicion, hypervigilance, and paranoia are common (Cohen, 1989; Erickson et al., 1987; Spotts and Shontz, 1980; Waldorf et al., 1991).
Extremely high does of cocaine like extremely high doses of many stimulant drugs can produce a toxic psychosis, with symptoms similar to the delirium of high fever. However, toxic psychoses appear to be rare among cocaine users, probably because of the body’s protective mechanisms referred to previously. In addition, because cocaine is relatively short acting, when psychosis does occur, it tends to be short-lived (Weil, 1986). Permanent psychosis is found occasionally among cocaine users (Washton, 1989; Weiss and Mirin, 1987), but there is no evidence of a causal link, and, for most people, even heavy and prolonged use appears to have no permanent impact on mental health, personality, mood, cognition, memory, or perception.
Among people predisposed to behave violently, cocaine may increase the likelihood of their involvement in violent episodes, but there is no evidence that cocaine causes generally nonviolent people to behave violently. Some researchers have identified crack as more violence producing than cocaine powder (Peterson, 199l; Washton, 1989), and journalists have been prone to attribute increases in violent crime to the pharmacological properties of crack.[21] However, a growing number of social scientists refute these claims.[22]
Crack use by women has also been blamed for rising rates of child abuse (Peterson, 199l). However, to the extent that crack users seem to “lose their mothering instinct” and begin abusing or neglecting their children, it is probably due less to the pharmacology of the drug than to the lifestyle that accompanies heavy involvement in the street drug scene regardless of the drug (Rosenbaum et al., 1990). In fact, research on a variety of drugs shows that the same drug is associated with very different behaviors in different cultures, which indicates that there is no direct link between any specific drug and any specific behavior (see, e.g., MacAndrew and Edgerton, 1969; Zinberg, 1984). In this culture, crack like alcohol is associated with violence primarily because it is often used by people already at high risk for behaving violently and because it is often used in social settings in which violence is already common (Williams, 1992). No drug directly causes violence simply through its pharmacological action.
Cocaine’s Physiological Effects
Because it constricts blood vessels and speeds up the heart, cocaine has the potential to produce cardiovascular disease. However, at low doses, the increases in blood pressure and heart rate caused by cocaine are fairly similar to those associated with over-the-counter appetite suppressants and are less dramatic than those experienced by most people during aerobic exercise, urban driving, or sex. With larger doses, cocaine’s cardiovascular effects become more pronounced, and users face an increased risk of harm to the heart through coronary artery constriction or arrhythmia. High-dose users also face an increased risk of adverse stimulant effects in the central nervous system, including seizures, convulsions, and strokes (Cregler and Mark, 1986).
Because intravenous injection allows the rapid delivery of a large dose of cocaine, injectors are more likely to experience adverse physiological effects. Rapid consumption of multiple doses increases the risk associated with other routes of administration, but the body’s capacity quickly to diminish cocaine’s effects protects even most high-dose smokers, sniffers, and swallowers from serious harm. Oral ingestion clearly has the greatest safety margin, although an extremely large dose swallowed can be dangerous, as indicated by the death of “body packers” people who swallow balloons or condoms filled with cocaine to smuggle it across borders (Amon et al., 1986; Suarez et al., 1977).
Although most people can consume a fairly high dose of cocaine with out serious harm, even a low dose can be dangerous for people with preexisting central nervous system or cardiac abnormalities (Isner et al., 1986; Mittleman and Wetli, 1987). People with enzyme deficiencies that interfere with cocaine’s biotransformation may also be at higher risk (Devenyi, 1989). There is recent evidence that consuming alcohol with cocaine may be risky, especially for persons with heightened sensitivity to cocaine’s effects (Karch, 1992).[23]