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Drug Effects on Sexual Arousal

Aphrodisiacs are mostly-mythical sub­stances that supposedly increase sexual desire and arousal. Most traditional aphrodisiacs are ineffective, and some can be toxic. If they work at all, it is due to placebo effects.

Viagra (sildenafil) is the most widely known medicine influencing sexual behavior. It successfully treats erectile disorders in men, although it has little effect on women.

Viagra does not improve sexual responsiveness or pleasure in healthy young people without sexual problems. If it does, it is a placebo effect.

What are aphrodisiacs?

Pleasure generally involves dopamin­ergic circuits of the limbic system. Those areas are strongly activated by orgasm.

Cocaine and other stimulant drugs also activate those areas, and those drugs can have a strong aphrodisiac effect for a beginning user. For a hard-core addict, stimulants may replace sex rather than enhancing it.

A woman who was injecting 4 to 6 grams of cocaine a day (and wrote an essay reproduced in Chapter 14) said at the peak of her addictoin she felt no sexual desire. Her "pleasure centers" could only be turned on by large amounts of cocaine.

Methamphetamine has a similar effect. Initially it activates sexual behavior, but over the long term it tends to replace sexual behavior.

Dopaminergic neurons of the limbic system, implicated in sexual cravings, are affected in Parkinson's Disease. When L-Dopa was discovered as a way of treating Parkinson's' Disease, re­searchers quickly discovered a serious side effect in some people: they became hypersexual.

What part of the nervous system is involved in sexual cravings?

Oliver Sacks (1976) wrote in his book Awakenings about one patient (Mr. L., age 49) who went from a 24-year state of semi-paralysis into a sexual frenzy. Given L-Dopa, his paralysis disappeared and he became mobile again. It seemed like a miracle, but trouble signs appeared:

...He wanted to touch and kiss all the nurses on the ward... Very rapidly, in May, relationships became strained, and Mr L. passed from a gentle amorousness to an enraged and thwarted erotomania.

Early in May he asked me if I could arrange for various nurses and nursing aids to "service" him at night, and suggested–as an alternative–that a brothel-service be set up to meet the needs and hungers of DOPA-charged patients.

...Driven at this time by libidinal force, he started to masturbate–fiercely, freely, and with little concealment–for hours each day. (Sacks, 1976, 246-256)

How did one of Oliver Sacks patients respond to L-Dopa?

Eventually Mr. L's condition turned into a psychosis with sexual hallucinations and paranoid delusions. This continued after reduction of his L-Dopa medication to a fraction of the original dosage. Finally, in August of the same year (1969) he was taken off L-Dopa entirely, whereupon he reverted to his original paralysis.

Mr. L's response illustrates the tie be­tween dopaminergic areas of the brain and so-called libido–energy derived from or related to sex. It also illustrates the relationship of excessive dopamine production to psychosis. Hypersexuality as a reaction to L-Dopa is common, although usually not this extreme.

What did the chemist who formulated Andron think about its effect?

Do humans react to odors as sexual attractants? In the late 1970s, several perfumes used androstenol, a substance found in armpit sweat of men, to stimu­late animal instincts of sexual attraction.

The makers of one cologne–Andron by Jovan–claimed to use human phero­mones (distance hormones common in the animal world) to stimulate sexual arousal. However, the chemist who form­ulated Andron did not believe in it.

He pointed out that sexual arousal in humans was always mediated by other cues (White, 1981). Other researchers failed to find any sex-attractant phero­mones for humans, using double-blind studies.

The role of alcohol in reducing sexual inhibition is notorious. In some people, alcohol "dis-inhibits" animal-like behaviors controlled by the limbic system, notably sex and aggression.

Alcohol leads to a distinctive mental state that researcher Claude Steele called alcohol myopia. Future events fade into insignificance while present stimuli dominate attention.

This is perhaps why alcohol encourages irresponsible sexual behavior. One AIDS counselor described alcohol as "the single most important risk factor in AIDS" because people who normally would protect themselves sometimes engage in unprotected sex when drunk.

Sexual inhibitions may be loosened by alcohol, but male sexual responsiveness is not improved. Farkas and Rosen (1976) used a penile plethysmograph, a pressure-sensitive ring, to measure the erectile response of young men who watched erotic films after consuming mixtures of orange juice and vodka.

As alcohol levels went up, response to the films first increased slightly (perhaps showing the anxiety-reducing effects of alcohol at low dosages) then went down. At very high levels of intoxication none of the men could sustain an erection. As Shakespeare put it, alcohol "provokes the desire, but takes away the perfor­mance." (Macbeth, Act 2, Scene 1)

How does alcohol affect sexual response?

Marijuana also releases sexual inhibitions (Koff, 1974) but does so through a chemical effect different from alcohol. Experiments with mice show that a dose of THC, the active ingredient in marijuana, produces a six-fold rise in testosterone within a few minutes (Greenberg, 1981) then a fall in testosterone after 20 minutes. Kolodny, Masters, and Johnson (1979) wrote:

How does marijuana affect testosterone levels in mice?

In our own research with more than 1,000 men and women aged eighteen to thirty-five who had used this drug as an accompaniment to sex, 83 percent of the men and 81 percent of the women said that marihuana improved their sexual experience. (p.412)

What did Kolodny, Masters, and Johnson report?

Normally, this kind of finding would be subjected to closer scrutiny through controlled research, but not in this case. A government-funded proposal for controlled experimentation on marijuana and sexual response was halted when legislators got wind of the research.

Part of the research involved showing arousing filmstrips to male volunteers, who had smoked marijuana or a placebo, while penile response was measured with a pressure-sensitive ring. Headlines ridiculed government sponsorship of "pot and sex research."

Under pressure from Congress, the federal grant was withdrawn (Holden, 1976). According to Masters, Johnson, and Kolodny (1982), this was the first time in United States history when a scientific project, approved and funded, was stopped due to public ridicule.

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References:

Farkas, G. M. & Rosen, R. C. (1976) Effect of alcohol on elicited male sexual response. Journal of Studies on Alcohol, 37, 265-272. doi:http://dx.doi.org/10.15288/jsa.1976.37.265

Greenberg, J. (1981, July 25). Marijuana use tied to changes in sex drive. New York Times, p.6.

Koff, W. C. (1974) Marijuana and sexual activity. Journal of Sex Research, 10, 194-204.

Masters, W. H., Johnson, V. E. & Kolodny, R. C. (1982) Human Sexual­ity. Boston, MA: Little, Brown & Co.

Sacks, O. (1976) Awakenings. New York: Vintage.

White, D. (1981, September). Pursuit of the ultimate aphrodisiac. Psychology Today, pp.9-12.


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