Background: Although there is high co-occurrence between ASD and ADHD, the nature of this co-occurrence remains unclear. Our study aimed to examine the underlying relationship between ASD and ADHD symptoms in a combined sample of children with a primary clinical diagnosis of ASD or ADHD. Methods: Participants included children and youth (aged 3-20 years) with a clinical diagnosis of ASD (n = 303) or ADHD (n = 319) for a total of 622 participants. Parents of these children completed the social communication questionnaire (SCQ), a measure of autism symptoms, and the strengths and weaknesses of ADHD and normal behavior (SWAN) questionnaire, a measure of ADHD symptoms. A principal component analysis (PCA) was performed on combined SCQ and SWAN items, followed by a profile analysis comparing normalized component scores between diagnostic groups and gender. Results: PCA revealed a four-component solution (inattention, hyperactivity/impulsivity, social-communication, and restricted, repetitive, behaviors, and interests (RRBI)), with no overlap between SCQ and SWAN items in the components. Children with ASD had higher component scores in social-communication and RRBI than children with ADHD, while there was no difference in inattentive and hyperactive/impulsive scores between diagnostic groups. Males had higher scores than females in social-communication, RRBI, and hyperactivity/impulsivity components in each diagnostic group.

The results suggest that neuropsychological measures of processing speed and cognitive flexibility may predict return to driving after TBI.

New neurons continue to be generated in the dentate gyrus (DG) region of the hippocampus throughout adulthood, and abnormal regulation of this process has emerged as an endophenotype common to several psychiatric disorders. Previous research shows that genetic risk factors associated with schizophrenia alter the maturation of adult-generated neurons. Here, we investigate whether early adversity, a potential environmental risk factor, similarly influences adult neurogenesis. During the first 2 weeks of postnatal life, mice were subject to repeated and unpredictable periods of separation from their mothers. When the mice reached adulthood, pharmacological and retroviral labelling techniques were used to assess the generation and maturation of new neurons. We found that adult mice that were repeatedly separated from their mothers early in life had similar rates of proliferation in the DG, but had fewer numbers of cells that survived and differentiated into neurons. Furthermore, neurons generated in adulthood had less complex dendritic arborization and fewer dendritic spines. These findings indicate that early adverse experience has a long-lasting impact on both the number and the complexity of adult-generated neurons in the hippocampus, suggesting that the abnormal regulation of adult neurogenesis associated with psychiatric disorders could arise from environmental influence alone, or from complex interactions of environmental factors with genetic predisposition.

This study supports the use of FIM at rehabilitation admission as a predictor of return to driving. Future studies should be directed at identifying other measures to be used in combination with FIM to accurately predict return to driving post-TBI.