Developmental, epidemiological, and neurobiological studies indicate that the adaptive and maladaptive functions, as well as immediate and long-term consequences of drug use, may vary by age. Early initiation seems to be associated with a reduced ability to use drugs purposely in a temporally stable, non-addictive manner. Prevention strategies should consider social environmental factors and aim to delay age at initiation.

Early and automatic neuropsychological processes may be influenced by altered dopaminergic functions but cannot be fully explained by these or by altered reinforcement and extinction processes. The reinforcement-extinction model is excellent for understanding certain causal pathways of attention-deficit/hyperactivity disorder, but it can hardly explain the heterogeneous developmental trajectories of ADHD fully. It should be integrated into a multiple pathways model.

Erickson's article links the concept of four tastes to color perception as a sensory modality with similar problems of categorization. Such problems are also present for odors and olfaction. Olfaction is the sensory modality with the closest physical relationship to taste, and the sense organs of both permanently interact. We discuss the origins and influences of core ideas of the science of smell to add to the discussion of unresolved categorization problems in taste from another, closely related point of view.

The closeness of somatosensory phenomena and emotional states can be critically extended into a clinical perspective by referring to Tourette's Syndrome (TS). Two examples are discussed in this commentary: (1) the neurodevelopmental approach to the pre- and post-tic sensorimotor urges, and (2) the TS treatment with deep brain stimulation. It is shown that in TS, both views (locationist and constructionist) need to be combined along the lifespan in order to get a more realistic picture of the brain basis of emotion.

Sleep disturbances are common for children with attention-deficit/hyperactivity disorder (ADHD) and are of great clinical significance. Brain dopamine plays an important role for both ADHD symptoms and sleep-wake regulation. We therefore suggest that one basic aspect of integrative brain-behavior relationship such as the sleep-wake cycle may certainly be addressed in a dynamic developmental theory of ADHD.

In developmental psychopathology, differentiating between the coexistence and the clinical entity of two problem areas is of utmost importance. So far, logistic regression analysis has already provided helpful answers, as shown in studies on comorbidity of tic disorders. While the concept of bridging symptoms may be investigated adequately by both logistic regression and the network approach, the former (latent variable) seems to be of advantage with regard to the problems of multiple comorbidities and development.

Cramer et al.'s network approach reconceptualizes mental comorbidity on the basis of symptom space originating from psychometric signatures. We argue that the advantages of this approach need to be regarded in the context of the multi-level functional organization of the neural substrate, ranging from neurogenetic to psychometric. Neuroelectric oscillations are proposed as a level-integrating principle.