Study 1
Campbell and colleagues (2002) conducted a long term study, evaluating the impact of the Abecedarian Project on young adults (aged 21 years) who had received the program when they were children. The pilot research began in 1971, and enrollment of participants into the program began in 1972 and lasted until 1977. The eligibility criterion was based on 13 sociodemographic factors that were weighted and combined to determine if a child and his/her family was considered high-risk. Moreover, to be eligible, infants could not have a biological condition associated with mental, sensory, or motor disabilities.
Four cohorts of families were randomized into preschool treatment or control status. A total of 109 families, which included 111 infants (1 pair of twins, and 1 sibling pair) were enrolled in the study. Fifty-seven infants (28 girls and 29 boys) were assigned to the treatment group and 54 infants (31 girls and 23 boys) were assigned to the control group. All families met poverty guidelines. The typical mother was young and had less than a high school education, was unmarried, and reported no income. Although ethnicity was not a selection factor, 98 percent of the sample was African American. The treatment and control groups received supportive social services as needed. Control infants had nutritional supplemental for the first 15 months of the treatment. Additionally although control group children did not receive the educational intervention, a number of them did attend other daycare centers.
The follow up study occurred when participants were 21 years old and included 105 of the original 111 infants. Contact with the young adults and their family was made via letter. Most participants were assessed within 1 month, on either side, of their 21st birthday. Young adults were contacted by letter inviting them to participate in the follow-up; telephone calls were a secondary form of contact, which also allowed for the scheduling of appointments. Of the original 111 participants, 105 were living and eligible for inclusion, of which 104 agreed to participate. All travel expenses were paid for those located outside of the study area, and participants were reimbursed $100 for their participation.
Data was collected through standardized tests, questionnaires, and an interview. The areas of interest included: intellectual level and academic skills, educational attainment, skilled employment, self-sufficiency, and social adjustment. To measure intellectual level and academic skill, the Wechsler Adult Intelligence-Scale Revised was used to evaluate intellectual levels (i.e., verbal and performance IQ scores), while the Woodcock-Johnson Psychoeducational Battery-Revised was used to evaluate academic skills in reading and mathematics. Educational attainment and skilled employment was evaluated through the young adult interview, where the youth would describe all educational attainment post high-school, as well as his/her current and previous employment. The responses were coded according to the Hollingshead Four-Factor Index of Socioeconomic Status, which rates skilled employment as 4 or higher (Hollingshead 1975). Self-sufficiently was gathered through the youth adult interview and rated on the Scale of Independent Living, which evaluated self-sufficiency in terms of economic support, living arrangements, transportation, and medical care. Finally, social adjustment was measured through the young person interview. Interviewees provided information on the number of convictions for misdemeanors or felonies, as well as the amount of time incarcerated or on probation. Additionally, substance abuse history was taken from the Youth Risk Behavior Survey provided to young adults.
General Linear Models were used to examine the treatment effects on the outcome variables. No subgroup analysis was conducted.
Study 2
Using the same sample as Study 1, McLaughlin and colleagues (2007) conducted a follow-up study to determine the impact of the Abecedarian Project on later depressive symptoms of young adults (at age 21) who had received the program when they were children. Participant’s included young adults who had enrolled in the Abecedarian Project as infants, including both the experimental and control groups. Young adults were contacted by letter inviting them to participate in the follow-up; telephone calls were a secondary form of contact, which also allowed for the scheduling of appointments. Of the original 111 participants, 105 were living and eligible for inclusion, of which 104 agreed to participate.
Data on participants’ depressive symptoms was collected through the Brief Symptom Inventory (BSI). The inventory provides three summary scores: Global Severity Index, Positive Symptom Total, and Positive Symptom Depressive Index. The scale consists of six items, which required respondents to rate the degree to which each problem applied to them within the last 7 days (e.g. “feeling blue,” “feeling no interest in things”).
Additionally, for both the treatment and control groups, home visits were conducted during the preschool years when children were approximately 6, 18, 30, 42, and 54 months old. During each visit, the age-appropriate version of the Home Observation for Measure of the Environment was completed. This scale is used to score observations of the parent and child at the home, as well as parents’ responses to questions about the family. Overall, this measurement was used to ensure that the home environment did not impact treatment effects.
A series of analyses were conducted to examine the impact of the Abecedarian program on young adult depression. To determine if the program predicted clinical levels of depression, the sample was dichotomized into “cases” and “noncases” based on the BSI clinical cutoff score of T=63.Logistic regressions with the home environment, preschool intervention group, and their interaction as predictors were then conducted to determine the impact of the Abecedarian program on young adult depression. No subgroup analysis was conducted.
