Liddle and colleagues (2001) found that Multidimensional Family Therapy (MDFT) resulted in the greatest and most consistent improvements in adolescent substance abuse and associated behavior problems.
The MDFT group had the greatest number of youth with a clinically significant reduction in drug use—45 percent versus 32 percent in Adolescent Group Therapy (AGT), and 26 percent in Multifamily Educational Intervention (MFEI).
There were no differences between groups in problem behaviors.
Only adolescents in the MDFT group reported significant improvements in grade point average. One year after treatment, 76 percent of MDFT youth had a C average or better (only 25 percent of youth had a C average or better when they were assigned to the MDFT group). For MFEI youth, 36 percent had a C average or better at program entry, which increased to 40 percent 1 year after treatment. For AGT youth, 43 percent had a C average or better at treatment entry, which increased to 60 percent 1 year posttreatment.
Only adolescents in the MDFT group reported significant improvements in family competence, moving from the behaviorally incompetent to the competent range. AGT families showed no change, while MFEI families demonstrated deterioration of the family functioning scales.
While Liddle and colleagues (2008) found that both group cognitive-behavioral therapy (CBT) and MDFT were effective in reducing cannabis and alcohol use, these reductions did not differ significantly between groups during treatment. However, MDFT participants reported significantly less substance use problem severity at the 6- and 12-month follow-up assessments than CBT participants, with larger effect sizes at 12 months than at 6 months. This result indicates that MDFT youth were better able to retain their treatment gains than CBT youth.
Both treatment groups experienced statistically significant reductions for other drug use, with results favoring MDFT.
Sixty-four percent of MDFT youth reported minimal or no substance use at the 12-month follow-up, while 44 percent of CBT youth reported minimal or no substance use—a statistically significant difference. This result indicates that MDFT youth were better able to retain their treatment gains than CBT youth.
Substance Use Problems and Frequency
Liddle and colleagues (2009) found that both the MDTF and peer group intervention groups showed reductions in the number of youth reporting substance use problems during the 1-year follow-up. MDFT participants experienced a more rapid decrease in substance use problems over the 12-month period (effect size d = .74). In a test of clinical significance, MDFT participants reported an average number of substance problems at 12 months comparable to a low-risk sample.
The proportion of youth abstaining from alcohol and drug use increased overall in the 12-month follow-up period. MDFT youth reported fewer days of substance use (effect size d = .77).
Although the overall sample did not significantly improve in either the proportion abstaining from delinquent behavior or frequency of delinquency behavior, youth receiving MDFT decreased their (log) delinquent behavior more rapidly than youth receiving peer group treatment (effect size d = .31). MDFT participants were less likely to be arrested or placed on probation during the 12-month follow-up.
MDFT youth demonstrated reduced scores on internalized distress more rapidly than group treatment participants (effect size d = .54).
Family Functioning, Peer Delinquency, and School Functioning
Overall, MDFT youth and group therapy youth did not report statistically significant increases in positive family interactions. However, MDFT youth reported greater improvement in youth-reported positive family interactions during treatment that were maintained in the follow-up period (effect size d = .27). They also reported greater decreases in negative family interactions during treatment that were maintained during the follow-up period (effect size d = .53).
Youth in both conditions showed decreases in affiliation with delinquent peers, but MDFT youth more rapidly decreased their affiliation during treatment, and maintained those gains during the follow-up period (effect size d = .67).
Academic performance of group treatment youth declined over time, while MDFT participants improved significantly. Conduct grades improved for MDFT youth and declined for group treatment youth (effect size d = .35).
Liddle and colleagues (2001) used an experimental design to assess the impact of three programs on adolescent drug use, antisocial and delinquent behaviors, and family functioning.
One hundred and eighty-two clinically referred marijuana- and alcohol-abusing adolescents were randomized to one of three treatments: Multidimensional Family Therapy (MDFT, n=47), Adolescent Group Therapy (AGT, n=53), or Multifamily Educational Intervention (MFEI, n=52). Thirty adolescents refused treatment. The amount of treatment in all three treatment conditions was controlled so each treatment consisted of 14 to 16 weekly, office-based therapy sessions. A theory-based multimodal assessment strategy measured symptom changes and prosocial functioning at intake, termination, and 6 and 12 months following termination.
Participants were drug-using adolescents who had, on average, a 2 ½-year history of drug use at the time of intake. The age range of participants was 13 to 18 years, with a mean age of 15.9 years. Eighty percent were male. Fifty-one percent were white non-Hispanic, 18 percent were African American, 15 percent were Hispanic, and 16 percent were of other ethnicities. Forty-eight percent came from single parent households, 31 percent came from two-parent households, and 21 percent lived with a stepparent. Median yearly family income was $25,000. Youth were primarily polydrug users, coupling near-daily use of marijuana and alcohol with weekly use of cocaine, hallucinogens, or amphetamines. Sixty-one percent were on juvenile probation.
Treatments were delivered by experienced community clinicians trained in model-specific competence. Attrition was 30 percent from MDFT (n=14), 35 percent from MFEI (n=18), and 47 percent from AGT (n=25).
Liddle and colleagues (2008) used an experimental design to examine effects of MDFT in comparison with cognitive-behavioral therapy (CBT) on drug use.
Two hundred and eighty-seven youth from a community-based drug abuse clinic were referred to the study; 224 completed an intake interview and agreed to participate. These adolescents were randomly assigned to one of two treatments (MDFT or individual CBT). Youth were between the ages of 12 and 17.5 years. The final sample was primarily male (81 percent), African American (72 percent), from single-parent households (58 percent), and had low income (38 percent reported total yearly family income of less than $10,000; 23 percent reported income between $10,000 and $20,000)—with 41 percent of families receiving public assistance. Forty-eight percent were referred by the juvenile justice system, 36 percent were from child welfare services agencies, 11 percent were from schools, and 5 percent were from other sources. All youth were drug users.
Five measures of drug use or abstinence (substance use problem severity, 30-day frequency of cannabis use, 30-day frequency of alcohol use, 30-day frequency of other drug use, 30-day abstinence) were assessed at intake, at the end of treatment, and again at 6 and 12 months following treatment termination. The analyses employed latent growth curve modeling (LGM) to assess individual client change.
Liddle and colleagues (2009) used an experimental design to assess the impact of MDFT and a peer group intervention with young teen substance users.
One hundred and thirty adolescents were referred to the study—45 percent by the juvenile justice system, 41 percent by schools, 2 percent by substance abuse/mental health facilities, and 12 percent by other sources (e.g., parents). Eighty-three were eligible and consented to participate. Seventy-four percent of participants were male; 42 percent were Hispanic, 38 percent were African American, 11 percent were Haitian or Jamaican, 3 percent were white non-Hispanic, and 4 percent were of other ethnicities. Forty-seven percent were involved in the juvenile justice system. Fifty-three percent lived in single parent homes, and median family income was $19,000. Youth ranged from 11 to 15 years of age; the average age was 13.73 years.
Youth and parents were assessed at intake, at 6 weeks post-intake, at discharge, and at 6 and 12 months following intake. Measures included the primary outcomes of substance use, delinquency, and internalized distress, and the secondary outcomes of family functioning, peer delinquency, and school functioning. Treatment lasted 4 months and was delivered by community agency therapists. Analyses used LGM. Ninety-seven percent of MDFT youth completed treatment; 72 percent of group therapy participants completed treatment.