Inhibitory control (IC) deficits have been associated with psychiatric symptoms in all ages. However, longitudinal studies testing the direction of the associations in childhood are scarce. We used a sample of 2,874 children (7 to 9 years old) to test the following three hypotheses: (a) IC deficits are an underlying risk factor with a potentially causal role for psychopathology, (b) IC deficits are a complication of psychopathology, and (c) IC deficits and psychopathology are associated at the trait level but not necessarily causally related. We used the go/no-go task to assess IC, the parent-rated Strengths and Difficulties Questionnaire to evaluate externalizing/internalizing symptoms, and the random intercepts cross-lagged panel model to test the hypotheses. The results showed no support for the underlying risk factor hypothesis, suggesting that IC unlikely has a causal role in this age group's psychopathology. The complication hypothesis received support for externalizing symptoms, suggesting that externalizing symptoms may hamper the normal development of IC. IC deficits and both externalizing and internalizing symptoms were correlated at the trait level, indicating a possible common origin. We suggest that it may be useful to support children with externalizing symptoms to promote and protect their IC development.

We report the heritability of response inhibition, latency, and variability, which are potential markers of genetic risk in neuropsychiatric conditions. Genetic and environmental influences on cancellation and restraint, response latency, and variability measured in a novel variant of the stop signal task were studied in 139 eight-year-old twin pairs from a birth cohort. Cancellation (50%), restraint (27%), and response latency (41%) showed significant heritability, the balance being non-shared environmental influences and/or error. Response variability was not heritable, with 23% of the variance attributable to shared environmental influences and 77% to non-shared environmental risk or error. The phenotypic correlation between response cancellation and restraint was −.44 and between response latency and restraint was .21. These phenotypic correlations were entirely genetic in origin. The phenotypic correlation between response variability and % successful inhibition was .27, but was not genetic. Cancellation and restraint were heritable and shared genetic influences, indicating that they may be influenced by a common gene or genes. Response latency was moderately heritable and shared genetic influences with restraint, but was not correlated with cancellation. Response variability was not heritable. These results support the potential of response inhibition and latency as endophenotypes in genetic research. (JINS, 2011, 17, 238–247)

Poor cardiac pumping efficiency has shown to lead to cognitive impairments in patients with cardiovascular disease (CVD). The current study examined the relationship between left ventricular ejection fraction and sustained attention and inhibitory processes measured by the Adaptive Rate Continuous Performance Task and the Go/No-go test. Participants were 67 older outpatients (age 68.5 ± 7.4) with a range of CVD. Associations between cognition and ejection fraction were examined via linear regression analysis. Results were consistent with the hypothesis that lower ejection fraction is significantly associated with decrements in sustained attention and vigilance. Overall, the results provide support for the hypothesis that a change in cardiac pumping leads to decrements in some aspects of attention; however, inhibitory processes are relatively spared. (JINS, 2009, 15, 137–141.)