Sample 2: Substance Abuse Study (“Sample 2”)

This cohort was selected to be at high risk for developing substance use disorders, for the purpose of study the etiology of substance use disorders from the preschool years until the time of greatest substance use involvement (Zucker et al, 2000).

The second sample consisted of parents from families who participated in the Michigan Longitudinal Study (Substance Abuse Study), an ongoing longitudinal study of the development of alcohol and other substance use disorders (Zucker et al., 2000). Families were recruited from the community based upon the alcoholism status of the father during the period of 1985 to 1993, when their target child was in preschool and the parents (focus of the present study) were aged 20 to 53. The recruitment community was the same as the first study above. Data were collected at the initial recruitment (Wave 1) and at 3-year intervals thereafter. At Wave 5 (12 years following recruitment), neuropsychological testing was administered to all parents participating in the study, including 30 stepparents who joined the study when they married a participant, and is the focus of the current report when the parents were aged 26 to 66, during the years 1996 to 2005. The battery used the same measures due to close collaboration among the investigators on the two studies (below). Examiners traveled to the families’ homes in order to administer the neuropsychological test battery. Privacy and minimal distractions were ensured throughout testing.

Court alcoholic families (n=159) were recruited when the father was convicted of drunk driving and had a high blood alcohol content, but was not currently undergoing litigation. A Certification of confidentiality was obtained to further support veridical reports of behavior and substance use. Control families (n=91), in which neither parent had a current or former diagnosis of substance use disorder were recruited using door-to-door canvassing in the neighborhoods of the court alcoholic families. Canvassing also uncovered community alcoholic families (n=61) in which the father met criteria for probable or definite alcoholism but had no recent drunk driving or drug-involved arrest. Both parents participated in nearly all instances. The participants sample thus comprised 607 men and women from these 311 families but not all were included here as described under “final sample.” Because parents were not genetically related and we had no evidence of assortative mating patterns that would affect our modeling, we treated these as independent observations for present purposes.

The SMAST (Selzer, Vinokur, & van Rooijen, 1975), the Drinking and Drug History Questionnaire (DDHQ;(Fitzgerald, Zucker, & Noll, 1990)), the Antisocial Behavior Inventory (ASB; (Zucker, Ellis, Bingham, & Fitzgerald, 1996; Zucker, Ellis, Fitzgerald, Bingham, & Sanford, 1996; Zucker, Noll, Ham, Fitzgerald, & Sullivan, 1993)) and the Diagnostic Interview Schedule, Version III (DIS; (Robins, Helzer, Croughan, & Ratcliff, 1981)) were completed and DSM–IV alcohol-related and ASPD diagnoses were established by two masters-degree or higher clinical raters with excellent inter-rater reliability (Zucker, Ellis, Bingham, et al., 1996; Zucker, Ellis, Fitzgerald, et al., 1996). For other disorders, the DIS diagnosis was utilized. Lifetime diagnoses were created by combining the retrospective data and information gathered at these five different time points (i.e., Wave 1 – Wave 5) for the disorders of interest in the present study. “Current” diagnoses were those for which the participants met criteria within one year of the neuropsychological assessment. ADHD was assessed by retrospective reporting of ADHD symptoms in childhood, using the DIS-IV Lifetime Form (Robins et al., 2000)

IQ was estimated with a four subtest short form of the WAIS-R(Wechsler, 1981)), current at that time: Picture Completion, Information, Arithmetic, Block Design. The WAIS R and WAIS-III have a full scale estimated IQ correlation > .90 (Wechsler, 2003).

We counted total disorders (below). Secondly, interviewers scored the Global Assessment of Functioning scale (GAF) on a scale from 0 (severely impaired) to 100 (high functioning). A subset of cases rated by two clinicians yielded acceptable agreement (intraclass r > .9).

Any participants who met criteria for lifetime diagnoses of psychosis, bipolar disorder, and IQ < 75 at any time point were removed from the data set. In reality, this led to exclusion for these criteria of approximately 2% of those who would otherwise qualify. In addition, participants were not allowed to have drunk more than two alcoholic beverages during the hour prior to testing, nor to be drunk from earlier alcohol use during the day. Information was collected on medication and drug use prior to testing but medication status was free to vary.

607 men and women from 311 families participated in some part of the substance abuse study. Since neuropsychological tests were administered only at Wave 5, individuals who had not completed at least half of the four tasks included in this study (i.e., Trail Making Test, Stroop Interference, Stop Signal Test, and WCST) were eliminated from further analyses (137 had completed none of the neuropsychological measures due to not having reached that wave), leaving 470 participants. Further rule outs were implemented from these 470 participants: schizophrenia-spectrum disorder or history of psychosis (n = 10), bipolar I disorder (n = 9), epilepsy (n = 1), and anti-psychotic and anti-mania medications (n = 2). This left a final n of 448.

Table 1 summarizes the similarities and differences in these two samples; the validity of combining them is evaluated empirically, below.

Comparison of the two samples included in the study

Note:

Stroop C,W=Stroop color naming and Stroop word naming condition, with the interference condition score partialed. Trails A=Trailmaking A, with the interference condition (B) partialed. Go RT=go trial reaction time on the stop-go task.