Course of SUDs
The courses of individuals’ SUDs vary by age of onset, severity, and chronicity4 and are shaped by personal and environmental influences. We consider separately the courses that AUDs and illicit drug use disorders can take.
Findings from three sets of longitudinal studies have contributed evidence about varying courses for AUDs: (1) how individuals are functioning at a long-term follow-up, (2) varying temporal trajectories based on retrospective data, and (3) trajectories over time for individuals who were studied prospectively. Because courses for treated and untreated individuals can differ,5 we consider separately studies of largely untreated community samples and treated samples that were followed for 8 years or more.
With regard to AUDs in community samples, Finney et al.6 provide information from seven long-term studies ofcommunity samples, all ofwhich included only men. Follow-ups ranged from 9 to 60 years, with remission rates varying from 27% to 69%. Dividing remission rates by the number of years of follow-up yields annualized remission rates. However, such rates could be calculated only for the two studies that had baseline samples of people diagnosed with current AUDs. In those studies, the annual remission rates averaged 3.9%. Within each study, remission was more frequent among individuals classified with alcohol abuse rather than alcohol dependence.7,8
In general, the definition of DSM-IV “abuse” used in these studies describes a pattern of substance use leading to significant problems or distress (e.g., failure to attend work or school, substance use in dangerous situations, such as driving a car, substance-related legal problems, continued substance use that interferes with friendships and/or family relationships), whereas DSM-IV “dependence” describes continued use of drugs or alcohol even when significant problems related to their use have developed. Signs ofdependence included an increased tolerance or need for increased amounts of the substance to attain the desired effect, withdrawal symptoms, unsuccessful efforts to decrease use, increased time spent in activities to obtain substances, withdrawal from social and recreational activities, and continued use of substances even with awareness of physical or psychological problems. It should be noted that DSM-V combines the DSM-IV categories of substance abuse and substance dependence into a single disorder measured on a continuum from mild to severe.
Retrospective data on trajectories of untreated AUDs have provided evidence of varying courses of AUDs. Four trajectories identified among 420
4 Course of Substance Use Disorders
middle-aged men in the Vietnam Era Twin Registry9 are depicted in Figure 4.1. For those exhibiting a “severe-chronic” course (13% of the sample), alcohol dependence diagnoses occurred at rates of 90-100% up to age 56. Men with a “severe-nonchronic” course (18%) were likely to have an alcohol dependence diagnosis up to age 41, after which diagnoses declined to less than 10-20% by age 51-56. The men in the “young-adult” group, comprising 44% of the sample, were diagnosed as dependent at a young age, but none had an alcohol dependence diagnosis at 42 years of age (although almost 10% had diagnoses later up to age 56). Finally, for those with a “late-onset” course (25%), alcohol dependence diagnoses increased to age 41, after which they declined to about 30% by age 56.
A later study of a non-twin sample of 323 Vietnam-era veterans replicated these trajectories.10 Both studies indicated that the course of AUD varies across individuals, with only a small percentage (13% of the men studied by Jacob et al.9) experiencing a chronic course. It should be noted, however, that by age 56, 28% of the latter sample9 met criteria for alcohol dependence. How well these findings can be generalized to women and to broader community samples is currently unknown.
Prospective data on the course of AUDs in community samples are less subject to the recall bias that may affect retrospective research. A classic
Figure 4.1 Trajectories of alcohol dependence diagnoses from age at first drink up to age 56. AD, alcohol-dependence; SC, severe chronic; S NC, severe nonchronic;
YA, young adult; LO, late onset. Reprinted with permission from Jacob, T., Koenig,
L. B., Howell, D. N., Wood, P. K., & Haber, J. R. (2009). Drinking trajectories from adolescence to the fifties among alcohol-dependent men. Journal of Studies on Alcohol and Drugs, 70(6), 859-869.
prospective study by Vaillant11 provided long-term follow-up data on two community samples—one comprising inner-city men (the “Core City” sample) and the other college men (the “College” sample). For Core City men, more than 25% met criteria for alcohol abuse by age 20. Although all of the Core City men were diagnosed with alcohol abuse at some point in the study, 51% also met criteria for alcohol dependence. Diagnoses of alcohol abuse and dependence in the Core City sample were highest at age 40, after which they declined. Forty was also the age at which the Core City men began to die, with more of those who died meeting criteria for alcohol abuse than being abstainers before their deaths. Among the survivors, about 60% resolved their alcohol abuse, either as abstainers or, less frequently, as controlled drinkers.
Alcohol abuse began at a later age for many men in the College sample, and a smaller percentage (38%) of the College men ever met criteria for alcohol dependence (although all met criteria for abuse at some point). Diagnoses of alcohol abuse and dependence peaked at a later age (50 years of age) than for the Core City men and continued later in the lives of many of the College sample men. Overall, roughly 2% of alcohol-dependent individuals became stably abstinent every year, and, after age 40, roughly 2% died every year.
More recent studies have covered less extended time periods and have provided less in-depth information relative to Vaillant’s study. However, there is consensus in prospective community studies that rates of AUDs tend to peak in late adolescence and decrease substantially into the mid-20s.12 In one study covering 9 years,13 21% of 134 adult men met diagnostic criteria again for an AUD after their initial baseline diagnosis, and another 23% had 3-year periods of recovery by the 6- or 9-year follow-up points. Although more than half (56%) of the men were not in recovery at the 9-year follow-up, only about 40% had exhibited a chronic course over the entire 9-year period.
A study by Schuckit and colleagues focused on an initial sample of 453 mainly white and highly educated men who had experience with alcohol and had been assessed at ages 18-24 and then every 5 years for the next 30 years. Of those, 63% never subsequently met criteria for an AUD, 17% had an AUD before age 30 and then a chronic course, 7% developed an AUD at or after age 30 followed by a chronic course, and 14% had an AUD before age 30 but maintained remission for more than 5 years before the 25-year follow-up.14 Of the 129 men who had an AUD at ages 28-33, 60% experienced a remission of 5 or more years by the 30-year follow-up, and 45% had sustained remission with no subsequent AUD diagnosis.15 Those with diagnoses of both alcohol and drug use disorders were more likely to have a chronic course than were those with either condition alone.16
With respect to long-term outcome of treated AUDs, providers of specialty alcohol-related treatment services are especially interested in what happens to patients in the long run after a treatment episode. Finney et al.6 summarized findings from 14 studies with 8- to 20-year follow-ups. Remission was variously defined as abstinence, non-problem drinking, substantially improved drinking, or no longer meeting diagnostic criteria for an AUD.
Rates of remission ranged from 21%17 to 83%.18 The average annual remission rate in the 14 studies was 4.7%, which is higher than the unweighted 3.9% average from the two community samples noted earlier. However, the higher annualized remission rate in treated samples cannot be attributed with confidence to the effect of treatment. The comparison between community and treated samples does not control for severity of disorder (which may have a curvilinear relationship with positive outcomes; that is, low- and high-severity individuals may have more positive outcomes than moderate-severity individu- als11) or differences in other risk factors, and it does not take into account differences in mortality rates. Analyses by Timko, Finney, and Moos19 yielded an annualized abstinence rate of 6.2% over 8 years among individuals without prior treatment when they initially contacted an alcohol information and referral or a detoxification center. This remission rate is higher than the average found in studies of community or treated samples and may reflect a more positive prognosis for these individuals given their lower initial problem severity and their motivation to seek help.
Women are underrepresented in long-term studies of AUDs. In particular, very few studies have investigated gender differences in long-term drinking outcomes among treated patients. A 16-year study of initially untreated women and men with alcohol problems found that women were more likely than men to participate in treatment and 12-step groups, and they experienced better alcohol-related and life context outcomes.20 These results were supported by a study of female and male outpatients in Spain who were followed prospectively for 20 years.21 Women had more early symptoms of dependence, started treatment earlier, and received more early treatment. They also consumed less alcohol than men did at follow-ups, but had similar levels of stress and psychosocial functioning. Women may also be more likely than men to initiate and sustain abstinence.22