Congratulations to FCRG member – Dr Kevin Butler – who has recently (along with his various collaborators) published a number of studies relevant to clinical psychology and related fields. Below we provide the reference (and link) for each study, along with a brief summary.
The first is:
Klaus K., Butler K., Durrant S. J., Ali M., Inglehearn C. F., Hodgson T. L., Gutierrez H., and Pennington K. (2017). The effect of COMT Val158Met and DRD2 C957T polymorphisms on executive function and the impact of early life stress. Brain and Behavior, 7(5): e00695. DOI: 10.1002/brb3.695
This study investigates the C957T (rs6277) polymorphism in the gene encoding the dopamine D2 receptor (DRD2) in healthy adult males. This polymorphism has been proposed to play a role in the development of schizophrenia. More specifically, the C allele has been associated with heightened schizophrenia risk in Caucasian samples. We show that CC carriers have impaired executive function (working memory and spatial planning). We also show, for the first time, impaired sustained attention performance in CC carriers who had experienced early life trauma compared to CC carriers without such experience. We argue that the DRD2 C957T polymorphism may confer vulnerability to schizophrenia through an impact on cognitive function and that some of these effects may be mediated by experience of early life trauma.
Butler K., Klaus K., Edwards L., and Pennington K. (2017). Elevated cortisol awakening response associated with early life stress and impaired executive function in healthy adult males. Hormones and Behavior, 95: 13-21. DOI: 10.1016/j.yhbeh.2017.07.013
The cortisol awakening response (CAR) is the typical rise in cortisol levels seen shortly after awakening. The CAR is thought to index hypothalamic-pituitary-adrenal axis (HPA-axis) functioning (the HPA-axis being one of our brains main stress response pathways) and has been shown to be aberrant in mental health disorders such as depression. Here we show that experience of trauma in childhood or adolescence is associated with elevated CAR. We also show that the age of trauma exposure, type of trauma exposure and cumulative exposure impacts on the CAR. Specifically, trauma during childhood, experience of physical abuse/violence and a greater number of traumas experienced appears to be associated with a more pronounced effect on the CAR. We also find a positive association between CAR and problem solving/planning performance. We argue that experience of early life trauma, elevated CAR and poor problem solving may reflect a phenotype that confers vulnerability to mental health disorders and suggest future research to confirm this hypothesis.
Butler K., Rusted J., Gard P., and Jackson A. (2017). Performance monitoring in nicotine dependence: considering integration of recent reinforcement history. Pharmacology Biochemistry and Behavior, 156: 63-70. DOI: 10.1016/j.pbb.2017.04.004
Impairments in performance monitoring (PM), our ability to monitor our own on-going behaviour for errors (e.g. when not being able to stop an action when we should) and conflict (e.g. when doing something that might initially be rewarding but that ultimately comes at a cost) have previously been reported in addicted populations including in nicotine dependent smokers. Contemporary models and behavioural evidence suggest that integration of previous reinforcement history (i.e. the collective information regarding the quality of our actions and choices and their outcomes over time) is an important feature of PM. However studies demonstrating PM impairments in addicted populations have typically used indices derived from reaction to task error or conflict on individual trials requiring little or no integration (e.g. post-error slowing – slowing of reaction time after an error, or error related negativity – an electrophysiological signal thought to derive from the anterior cingulate cortex after an error). This study investigates PM in current, former and never smokers using a reinforcement learning task that requires participants to integrate information regarding choices and their outcomes in order to do well. We show that former smokers (mean: 20.47 months abstinent) have the best PM ability and that current smokers (particularly those who recently smoked) have the worst PM ability. We argue that PM may be a good cognitive target for smoking cessation and suggest future prospective and intervention studies to examine this further.