Behavioral Effects

Cocaine administered intranasally produces stimulant effects similar to those of amphetamines, but with a much shorter duration of action (20–45 min), including feelings of having much energy, fatigue reduction, a sense of well being, increased confidence, and increased talkativeness. Intoxication includes a euphoric effect that has been described as exhilarating, with a kind of rush that “goes straight to one’s brain,” mild elation, and an enhanced ability to concentrate. Sigmund Freud wrote:

“The psychic effect of cocaine in doses of 50–100 mg consists of exhilaration and lasting euphoria, which does not differ in any way from the normal euphoria of a healthy person.”

“The psychic effect of cocaine in doses of 50–100 mg consists of exhilaration and lasting euphoria, which does not differ in any way from the normal euphoria of a healthy person.”

In a letter to his fiancée Martha, dated June 2, 1884, he wrote:

“ ... a small dose lifted me to heights in a wonderful fashion”

(Jones E. The Life and Work of Sigmund Freud. Basic Books, New York, 1961).

When taken intravenously or smoked, cocaine produces an intense euphoria, sometimes followed by a crash (a very sudden drop in mood and energy). William Burroughs wrote in 1959:

“When you shoot coke in the mainline there is a rush of pure pleasure to the head...Ten minutes later you want another shot...intravenous C is electricity through the brain, activating cocaine pleasure connections.”

(Burroughs WS. The Naked Lunch. Grove Press, New York, 1959).

Cocaine has many of the same stimulant effects as amphetamines, including sustained performance in situations of fatigue. A study with normal, healthy volunteers tested with a wide range of intravenous doses of cocaine or D-amphetamine showed that cocaine produced many of the same subjective and physiological effects as D-amphetamine, although D-amphetamine was more potent (Figure 4.4, Box 4.6).

Amphetamines in recreational dose ranges produce stimulant effects, but the most dramatic effects are observed in situations of fatigue and boredom. Such stimulant effects can translate into enhanced performance in these situations and include increased stimulation, improved coordination, increased strength and endurance, increased mental and physical activation, and improved subjective sensations of fatigue. Mood changes include boldness, elation, and friendliness. Amphetamines also enhance performance in simple motor and cognitive tasks, including measures of reaction time, speed, attention, and performance (Figure 4.5). Amphetamines can also improve athletic performance by small amounts (0.5–4%), and these superficially negligible improvements might be sufficient in highly competitive situations (Table 4.3).

Figure 4.4 Mean change in scores on five separate scales of the Addiction Research Council Inventory (ARCI). A short form of the ARCI was answered prior to drug or saline injection and again 15 min after the injection. The scales included amphetamine, benzedrine, and pentobarbital-chlorpromazine-alcohol.[Taken with permission from Fischman MW, Schuster CR, Resnekov L, Shick JFE, Krasnegor NA, Fennell W, Freedman DX. Cardiovascular and subjective effects of intravenous cocaine administration in humans. Archives of General Psychiatry, 1976, (33), 983–989.] These data show that cocaine and D-amphetamine are identified by subjects as euphoric, amphetamine-like, and not sedative. The morphine–benzedrine scale is a measure of euphoria. The pentobarbital–chlorpromazine–alcohol scale is a measure of sedation. The amphetamine scale is a measure of “amphetamine-like.” See page 247 of Martin WR, Sloan JW, Sapira JD, Jasinski DR. Physiologic, subjective, and behavioral effects of amphetamine, methamphetamine, ephedrine, phenmetrazine, and methylphenidate in man. Clinical Pharmacology and Therapeutics, 1971, (12), 245–258.

Nonetheless, stimulants such as the amphetamines and cocaine can also fail to improve performance in well-functioning, motivated subjects, and little evidence suggests that amphetamines can enhance intellectual functioning in complex tasks or tests of intelligence. One study found that methamphetamine failed to improve performance on a complex attention task, although it did increase the rate at which a visual display was scanned. An inverted U-shaped dose–response function that inversely relates stimulant dose to cognitive performance has been hypothesized, in which lower doses may improve performance, but higher doses decrease performance (Figure 4.6). As the dose of stimulant increases, behavior becomes progressively more constricted and repetitive, resulting in both cognitive and behavioral perseveration. However, the effects of the drug depend on initial conditions. The memory-enhancing effects of methylphenidate (or Ritalin, a stimulant used to treat attention-deficit/hyperactivity disorder), for example, depend on healthy subjects’ baseline performance on the same memory task in an undrugged state, such that greater improvement was observed in subjects with lower baseline memory capacity.

Other acute actions of amphetamines and cocaine include a decrease in appetite, for which these drugs have been used therapeutically and to which tolerance develops (Table 4.4). Trials over 4 weeks reported significant weight loss; trials over 6 months reported no significant effects. Amphetamines also decrease sleepiness, increase the latency to fall asleep, increase the latency to the onset of rapid-eye-movement (REM) sleep, and reduce total REM sleep.

Figure 4.5 Performance on a cycle ergometer in humans after treatment with the psychostimulant methedrine. [From: Cuthbertson DP, Knox JAC. The effects of analeptics on the fatigued subject. Journal of Physiology, 1947, (106), 42–58.] This very early study showed that administration of methedrine (methamphetamine) to a human sustained performance on a stationary bicycle long past when a placebo-treated individual fatigued.


Comparative Effects of Amphetamine Sulfate and Placebo on Swimming Performance Times in Subjects∗ Under Rested and Fatigued Conditions

Three subjects performed each of the swim tasks specified, under both the rested (1st swim) and fatigued (2nd swim) conditions. The 2nd swim occurred 15 min after the 1st swim.

[Data from Smith GM, Beecher HK. Amphetamine sulfate and athletic performance: I. Objective effects. Journal of the American Medical Association, 1959, (170), 542–557.]

BOX 4.6


A 19-year-old white male had been experimenting with a variety of drugs, including snorting cocaine, for approximately two years. He had used cocaine exclusively in a recreational setting and indicated that he found nothing but pleasure in the drug experience and never had any problem, nor had he escalated his dose. One day a group of friends were injecting cocaine and they persuaded him to try this route of administration. As he had had no difficulty with cocaine previously, and as a result of curiosity and peer group pressure, he decided that he would experiment with injection. Following the intense stimulation and rush he became acutely anxious and frightened. Upon arrival at the Medical Section of the Haight-Ashbury Free Medical Clinic, he was found to have a very rapid pulse rate as well as a hyperventilation administered anxiety. He was treated with 10 mg of i.v. Valium(R) administered slowly with reassurance. To cease the carpopedal spasms he had developed as a consequence of his hyperventilation syndrome, he was told to breathe into a paper bag which increased his carbon dioxide levels. The acute anxiety and its subsequent sequelae faded in approximately three hours. Follow-up indicated no recurrences or further experimentation with intravenous injection of cocaine by this individual. This use of intravenous sedative hypnotic medication is controversial and some critics of this approach use oral medication only while others stress reassurance alone without medication. We would recommend intravenous Valium(R) only after nonpharmacological intervention has failed. Wesson DR, Smith DE, Cocaine: its use for central nervous system stimulation including recreational and medical uses. In: Petersen RC, Stillman RC (Eds.), Cocaine: 1977, (series title: NIDA Research Monograph, vol. 13), National Institute on Drug Abuse, Rockville MD, 1977, pp. 137–152.

Finally, amphetamines and cocaine have long been reported to heighten sexual interest and prolong orgasm. In some instances, such delays in ejaculation have led to marathon bouts of intercourse that last for hours and may reflect some of the behavioral psychopathology produced by these drugs. However, with chronic amphetamine and cocaine abuse, psychostimulants can lead to significant decreases in sexual performance with prolonged use of the drug.

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