Pubertal Timing and Tempo: A Multiple Indicator Approach

• In Event: 3-212 - Toward Multisystemic Models of Pubertal Timing and Tempo

Integrative Statement

Previous research has emphasized two key facets of pubertal development: timing, or the onset of the maturation process, and tempo, or the rate at which an individual progresses toward reproductive maturity (Mendle, Harden, Brooks-Gunn, & Graber, 2010). Measurement of these facets typically relies on limited indicators derived from clinician-rated measures (e.g., Tanner stages). Although puberty encompasses multifaceted change across diverse physical traits, limited research has characterized variations in timing and tempo across different physical traits and secondary sex characteristics. Research that has investigated such differences has found that timing and tempo differ across and within pubic hair growth and genital development in boys and breast development in girls (Marceau, Ram, Houts, Grimm, & Susman, 2011). In the current study, we extend this work by evaluating mean and individual differences in the timing and tempo of five physical traits in a longitudinal sample of both boys and girls.
Participants were 463 children and adolescents (ages 8-19, 50.3% female) from the Texas Twin Project (Harden, Tucker-Drob, & Tackett, 2012). Participants rated the progression of their secondary sex characteristics and physical development at two time points. Mean age at Time 1 was 12.51 years (SD = 2.30 years, range = 7.80 – 16.57 years) and 15.17 years (SD = 2.20 years, range = 8.84 – 18.98 years) at Time 2. The average lag between time points was 2.66 years. Nonlinear mixed-effects models were fitted to characterize age-related trajectories of each item across Wave 1 and Wave 2. Freely estimated, model-derived scores for timing and tempo of each trait were extracted for each individual. Analyses focus on mean differences in timing and tempo across items and individual differences within items.
Figure 1a and 1b display the nonlinear logistic growth curves for five physical traits in boys and girls. Table 1 displays the parameter estimates for each of these models. In boys, facial hair was the slowest trait to emerge, though it progressed to completion most quickly. In females, body hair displayed the fastest rate to completion, excluding menarche, which was modeled dichotomously. Timing of menarche showed the least amount of variance across traits in both men and women.
To our knowledge, this is the first study to look at differences in timing and tempo across a wide range of physical traits relevant to pubertal development. We present here initial parameter estimates from the nonlinear growth curve models as descriptive results. Presentation results will focus on significant differences between traits in timing and tempo. Identifying differences in the trajectories of physical changes during puberty may be utilized to better understand of the differential contributions of these changes to vast psychosocial outcomes during adolescence.

Authors

• James Madole, University of Texas at Austin
  Presenting Author

• Elliot M. Tucker-Drob, University of Texas at Austin
  Non-Presenting Author

• Kathryn Paige Harden, University of Texas at Austin
  Non-Presenting Author