ADHD, stimulant treatment, and growth: a longitudinal study

Abstract

Background and objective: There is ongoing concern that stimulant medications may adversely affect growth. In a sample of attention-deficit/hyperactivity disorder (ADHD) cases and controls from a population-based birth cohort, we assessed growth and the association between stimulant treatment and growth.

Methods: Subjects included childhood ADHD cases (N = 340) and controls (N = 680) from a 1976 to 1982 birth cohort (N = 5718). Height and stimulant treatment information were abstracted from medical records and obtained during a prospective, adult follow-up study. For each subject, a parametric penalized spline smoothing method modeled height over time, and the corresponding height velocity was calculated as the first derivative. Peak height velocity (PHV) age and magnitude were estimated from the velocity curves. Among stimulant-treated ADHD cases, we analyzed height Z scores at the beginning, at the end, and 24 months after the end of treatment.

Results: Neither ADHD itself nor treatment with stimulants was associated with differences in magnitude of PHV or final adult height. Among boys treated with stimulants, there was a positive correlation between duration of stimulant usage before PHV and age at PHV (r = 0.21, P = .01). There was no significant correlation between duration of treatment and change in height Z scores (r = -0.08 for beginning vs end change, r = 0.01 for end vs 24 months later change). Among the 59 ADHD cases treated for ≥3 years, there was a clinically insignificant decrease in mean Z score from beginning (0.48) to end (0.33) of treatment (P = .06).

Conclusions: Our findings suggest that ADHD treatment with stimulant medication is not associated with differences in adult height or significant changes in growth.

Keywords: adult outcomes; attention-deficit/hyperactivity disorder; growth; height; stimulant medications.

FIGURE 1

Measured (open circles) height, estimated (dashed line) height, and estimated height velocity (solid bold line) from the parametric penalized spline smoothing method for 2 non-ADHD subjects. A, Male subject with peak height velocity = 12 years. B, Female subject with peak height velocity = 11.1 years.

FIGURE 2

Box plots of the estimated age at PHV, by ADHD case status and cumulative stimulant duration. Among the 217 ADHD cases with a PHV, 6 had unknown information on stimulant duration and are not displayed.

FIGURE 3

Box plots of the estimated magnitude of PHV, by ADHD case status and cumulative stimulant duration. Among the 217 ADHD cases with a PHV, 6 had unknown information on stimulant duration and are not displayed.

FIGURE 4

Relationship between change in gender-specific height-for-age Z scores before and after stimulant treatment and cumulative stimulant duration.

FIGURE 5

Relationship between change in gender-specific height-for-age Z scores after stimulant treatment and 24 months later and cumulative stimulant duration.