Overview
Executive functioning is a theoretical construct representing a domain of cognitive processes that regulate, control, and manage other cognitive processes. Executive functioning is not a unitary concept; it is a broad description of the set of processes involved in certain areas of cognitive and behavioural control. Executive processes are integral to higher brain function, particularly in the areas of goal formation, planning, goal-directed action, self-monitoring, attention, response inhibition, and coordination of complex cognition and motor control for effective performance. Deficits of the executive functions are observed in all populations to varying degrees, but severe executive dysfunction can have devastating effects on cognition and behaviour in both individual and social contexts.
Executive dysfunction does occur to a minor degree in all individuals on both short-term and long-term scales. In non-clinical populations, the activation of executive processes appears to inhibit further activation of the same processes, suggesting a mechanism for normal fluctuations in executive control. Decline in executive functioning is also associated with both normal and clinical aging. In aging populations, the decline of memory processes appears to affect executive functions, which also points to the general role of memory in executive functioning.
Executive dysfunction appears to consistently involve disruptions in task-oriented behavior, which requires executive control in the inhibition of habitual responses and goal activation. Such executive control is responsible for adjusting behaviour to reconcile environmental changes with goals for effective behaviour. Impairments in set shifting ability are a notable feature of executive dysfunction; set shifting is the cognitive ability to dynamically change focus between points of fixation based on changing goals and environmental stimuli. This offers a parsimonious explanation for the common occurrence of impulsive, hyperactive, disorganized, and aggressive behaviour in clinical patients with executive dysfunction. Executive dysfunction, particularly in working memory capacity, may also lead to varying degrees of emotional dysregulation, which can manifest as chronic depression, anxiety, or hyperemotionality. Russell Barkley proposed a hybrid model of the role of behavioural disinhibition in the presentation of ADHD, which has served as the basis for much research of both ADHD and broader implications of the executive system.
Other common and distinctive symptoms of executive dysfunction include utilization behaviour, which is compulsive manipulation/use of nearby objects due simply to their presence and accessibility (rather than a functional reason); and imitation behaviour, a tendency to rely on imitation as a primary means of social interaction. Research also suggests that executive set shifting is a co-mediator with episodic memory of feeling-of-knowing (FOK) accuracy, such that executive dysfunction may reduce FOK accuracy.
There is some evidence suggesting that executive dysfunction may produce beneficial effects as well as maladaptive ones. Abraham et al. demonstrate that creative thinking in schizophrenia is mediated by executive dysfunction, and they establish a firm etiology for creativity in psychoticism, pinpointing a cognitive preference for broader top-down associative thinking versus goal-oriented thinking, which closely resembles aspects of ADHD. It is postulated that elements of psychosis are present in both ADHD and schizophrenia/schizotypy due to dopamine overlap.
Read more about this topic: Executive Dysfunction