Recent decades have seen a marked increase in awareness of the importance of gender in medical treatment and research. In the complex field of drug abuse research, scientists have helped us understand that there are genetic, physiological, psychosocial, and environmental dimensions to drug abuse and addiction. Male and female differences in any of these dimensions can give rise to gender differences in the causes, effects, and consequences of drug abuse. Researchers and clinicians have developed a repertoire of effective treatment and prevention principles that can now be enhanced through their adaptation for the differing needs of men and women and boys and girls.
NIDA's National Drug Abuse Treatment Clinical Trials Network adheres to the overall National Institutes of Health requirement for analysis of data by gender and supports gender-specific protocol development. NIDA recently issued a Program Announcement for support of dissertation research in five areas, one of which is women and gender. A new Program Announcement on Women and Gender Differences will be issued soon to fund research specifically in the areas of epidemiology, prevention, and treatment. These efforts will build on NIDA-sponsored research that has established that important gender effects exist in biological and behavioral responses to drugs, risk for drug abuse, and treatment response.
Response to drugs: The neurobiological basis of drug abuse and addiction is essentially the same, regardless of the drug taken or the person taking it. Still, males and females may differ in their biological and behavioral responses to drugs. Laboratory studies have revealed sex-related differences in the ways that male and female animals metabolize drugs, the amount of drug they will self-administer, how soon after their first exposure they begin to administer drugs, and their vulnerability to relapse after abstinence. Preliminary results from studies of human drug abusers appear to be consistent with the findings from animal studies of gender differences in the patterns and the biological impact of drug use. For example, women typically progress from first use of cocaine, heroin, or marijuana to dependence more quickly than men. Additionally, cocaine-induced cognitive impairments and risk for stroke have been found to be more severe in men than in women.
Risk for drug abuse: While risk factors related to drug abuse vulnerability in males and females largely overlap, a variety of differences exist. Depression is much more common among women than men in the general public. This gender difference is much less pronounced among drug abusers. Possible explanations are that depression is a more potent risk factor for drug abuse among men than among women, or that drug abuse itself is more likely to cause depression among men than among women. Other risk factors that appear to be stronger for one gender than the other include conduct disorders, which correlate more with drug abuse by adolescent females, and aggression, which correlates with drug abuse by adolescent males.
Along with these differences, studies of gender and risk have revealed an unexpected and important similarity between males and females. Most experts long assumed that females were less attracted to or more wary of drug abuse than were males. That seemed a straightforward conclusion based on the fact that the percentage of women who abuse drugs is lower than the percentage of men who abuse drugs. However, the conclusion turns out to be not true. A recent study found that the lower rate of drug abuse for females is largely a matter of opportunity. (See "Gender Differences in Prevalence of Drug Abuse Traced to Opportunities to Use".) During the youthful ages when most drug abuse initiation occurs, more boys than girls receive offers of drugs. When drug offers are made, both genders are equally likely to accept. Once having accepted, males and females generally are equally likely to become dependent. This underscores the importance of drug refusal skills in prevention efforts with both genders.
Response to treatment: Success in drug treatment is directly associated with the length of time spent in treatment: The more time in treatment, the better the outcome. Science-based drug treatments are equally effective for men and women, but women often spend less time than men in treatment. In part, this could reflect differences in social and economic circumstances. Women entering treatment are more likely than men to be custodial parents and to have fewer economic resources; they are less likely than men to have graduated from high school, to be employed, or to have sufficient supportive social networks. Studies also indicate that males and females tend to relapse to drug use for different reasons. For example, among men relapse is more likely to be associated with anxiety and positive feelings, while among women depression and negative feelings appear to be more common triggers. All these differences suggest that it may be possible to enhance the effectiveness of treatment by tailoring it for the patient's gender.
The area of nicotine addiction is one in which our understanding of gender effects is relatively advanced, although still far from complete. Research has shown that different aspects of smoking more strongly influence addiction to nicotine in men and women. For men, the compulsion to smoke is driven more strongly by nicotine's pharmacological effects on the brain, while women's addiction owes more to the visual, tactile, taste, and olfactory sensations involved in smoking. Because of these differences, men tend to get more relief overall from nicotine replacement therapy, and women who use nicotine replacement do better with nicotine inhalers than the nicotine patch. Recent NIDA research also suggests that women can increase their chances for quitting by timing their attempt to coincide with the first half of their menstrual cycles, since nicotine craving and withdrawal symptoms are generally more severe during the second half of their cycles.
Although the focus on gender is relatively new in drug abuse science, we already know that gender's impact is far reaching and complex. A comprehensive and detailed picture of gender-related effects can lead to improvements in treatment and prevention efforts that bring us closer to the goal of individualized interventions that best meet the distinct needs of each patient. When it comes to reducing the tremendous burden of drug abuse and addiction, gender most certainly matters