In this commentary, we critique the appropriate behavioural features for evolutionary genetic analysis, the role of the environment, and the viability of a general evolutionary genetic model for all common mental disorders. In light of these issues, we suggest that the authors may have prematurely discounted the role of some of the mechanisms they review, particularly balancing selection. (Published Online November 9 2006).

The negative impact of adverse experiences in childhood on neurodevelopment is well documented. Less attention however has been given to the impact of variations in “normative” parenting behaviors. The influence of these parenting behaviors is likely to be marked during periods of rapid brain reorganization, such as late childhood. The aim of the current study was to investigate associations between normative parenting behaviors and the development of structural brain networks across late childhood. Data were collected from a longitudinal sample of (...) 114 mother-child dyads, recruited from low socioeconomic areas of Melbourne, Australia. At the first assessment parenting behaviors were coded from two lab-based interaction tasks and structural magnetic resonance imaging scans of the children were performed. At the second assessment, approximately 18 months later MRI scans were repeated. Cortical thickness was extracted from T1-weighted images using FreeSurfer. Structural covariance networks were constructed from partial correlations of CT estimates between brain regions and estimates of network efficiency and modularity were obtained for each time point. The change in these network measures, from Time 1 to Time 2, was also calculated. At Time 2, less positive maternal affective behavior was associated with higher modularity, while negative maternal affective behavior was not related. No support was found for an association between local or global efficacy and maternal affective behaviors at Time 2. Similarly, no support was demonstrated for associations between maternal affective behaviors and change in network efficiency and modularity, from Time 1 to Time 2. These results indicate that normative variations in parenting may influence the development of structural brain networks in late childhood and extend current knowledge about environmental influences on structural connectivity in a developmental context. (shrink)