Inhibition, shifting and updating in relation to psychometric intelligence across ability groups in the psychiatric population

Abstract

Background Assessment of intelligence and executive function (EF) is common in complex neuropsychiatric practice. Although previous studies have shown that EF and intelligence are related, it is unknown whether these constructs relate to one another in a similar manner across different ability groups (mild intellectual disability, borderline intellectual disability and normal/high intelligence). This study therefore examines the relation between three EFs (inhibition, shifting and updating) and intelligence in a heterogeneous psychiatric sample. It is hypothesised that the strength of the relation between intelligence and the three EFs decreases when the level of intelligence increases, in accordance with Spearman's Law of Diminishing Returns. Methods In a cross‐sectional, between and within subject design, one of the three intelligence tests (Kaufman Adolescent and Adult Intelligence Test and Wechsler Adult Intelligence Scale – third and fourth editions) and several EF tests (Stroop Colour–Word Test, Trail Making Test and Spatial Working Memory task) were administered to 250 neuropsychiatric inpatients and outpatients (Mage = 39.8, standard deviation = 14.3, 52.8% male). Based upon their full‐scale IQ score, patients were divided into three ability groups (mild intellectual disability, borderline intellectual disability or normal/high intelligence). The relation between EF and intelligence was assessed through analyses of the correlation pattern; groups were compared using analysis of covariance. Results Analyses showed significant correlations between the constructs of EF and intelligence. A significant interaction effect was found for shifting, with highest correlations in the normal to high intelligence group, but not for inhibition and updating. Conclusions Results support a specific role for shifting in this EF–intelligence relation. The correlational pattern of updating and intelligence, as well as the differential relation of shifting and intelligence across ability groups, suggests that EF tasks may not measure distinct EFs in lower intellectual ability but rely on cognitive primitives such as processing speed. EF tasks can be considered less valid indicators of EF ability. Implications in terms of the need for development of specific tasks to measure cognition in low intellectual ability are discussed.

Set Shifting and Inhibition Deficits as Potential Endophenotypes for Depression

“…Processing speed is associated with both MDD (Austin et al, 2001;Sarapas et al, 2013) and set-shifting and inhibition, and many set-shifting or inhibition tasks are conducted under time constraint, meaning that processing speed can directly affect the measurement of setshifting and inhibition (Bessette et al, 2020). Similarly, measures of general intellectual functioning (e.g., full scale IQ [FSIQ]) are correlated with specific EF components such as setshifting and inhibition (e.g., Biesmans et al, 2019), and are also lower in individuals with MDD relative to healthy controls (Ahern and Semkovska, 2017). Therefore, studies that do not address processing speed or general intellectual functioning as potential confounds cannot disentangle whether deficits in set-shifting or inhibition performance are truly deficits in these processes or instead reflect deficits in processing speed or general cognitive functioning.…”

“…As general intelligence is associated with set-shifting and inhibition (e.g., Biesmans et al, 2019), the Wechsler Test of Adult Reading (Holdnack, 2001) was used to estimate each participant's full-scale IQ (FSIQ). The WTAR asks participants to pronounce 50 irregularly spelled words, with each participant's raw score reflecting the number of words correctly pronounced.…”

The relationship between executive dysfunction and neuropsychiatric symptoms in patients with Korsakoff’s syndrome

“…Low test performances in people with lower mental abilities (due to younger age, lower intelligence or neurological disorders) might thus reflect a (diminished) general ability (g) rather than specific cognitive impairment. The unity/diversity model seems to capture the organization of executive functions mainly in cognitively healthy adult populations, which may not be applicable in lower-ability groups (Biesmans et al, 2019;Janssen et al, 2013;Karr et al, 2018). Earlier studies that found a significant association between executive dysfunction and neuropsychiatric symptoms (Brodaty et al, 2012;McPherson et al, 2002) did not take general cognitive functioning into account and used executive measures that could be argued to be task impure.…”

Behavior and cognitive functioning in Witteveen–Kolk syndrome

“…Furthermore, a measure of sustained (d2 sustained‐attention test) attention was obtained, as well as measures of executive functions that focus on planning and organization (subtasks “Key search” and “Zoo map” of the Behavioural Assessment of the Dysexecutive Syndrome for Children). Executive functioning refers to complex control mechanisms such as planning, shifting and monitoring that enable a person to perform effective, goal‐directed and self‐regulating behavior (Barkley, 2012; Biesmans, van Aken, Frunt, Wingbermühle & Egger, 2019; Lezak, Howieson, Tranel & Bigler, 2012; Salthouse, 2005). As for memory functioning, learning tasks with both auditory and visual stimuli were performed (Auditory Verbal Learning Test, Rey Complex Figure Test).…”