There are some contradictions with the primary source materials. Two of the studies that were identified as drug free (i.e., from previous medication exposure) in Figure 4 were drug naive. The subjects in the la Fougère et al. study (2) were designated as “drug free” in Table 1, but ADHD subjects were drug naive. The second study is not explicitly identified in Figure 4 but can be inferred because 1) Figure 4 shows three studies in which all ADHD subjects had previous exposure, yet Table 1 lists only two studies in this category, and 2) Figure 4 shows four studies as drug naive, yet Table 1 lists five studies with drug-naive subjects. Table 1 lists the Dougherty et al. study (3) as 100% previous exposure when, as indicated in a clarification published in Lancet (4), there was 67% exposure. The Volkow et al. study (5) is listed and analyzed as if subjects were drug naive, but an earlier version of this Volkow et al. study (6) stated, “Subjects were excluded if they had a prior history of more than 1 month of medication treatment for ADHD.” The Jucaite et al. study (7) appears to fit the Figure 4 regression, as the three subjects with previous drug exposure appear to account for elevated mean dopamine transporter binding of ADHD subjects. Yet, the opposite conclusion can be drawn from the primary source manuscript, in which Figure 3 shows that ADHD subjects with previous medication exposure had lower average dopamine transporter binding (estimated 8 units) than drug-naive ADHD subjects (estimated 10 units). Thus, the Jucaite et al. data support the view that previous stimulant treatment is not associated with increased dopamine transporter binding but overall lower dopamine transporter binding.