The relationship between executive functions and fluid intelligence in Parkinson's disease

Abstract

<jats:sec id="S0033291712000451_sec_a001"><jats:title>Background</jats:title><jats:p>We recently demonstrated that decline in fluid intelligence is a substantial contributor to frontal deficits. For some classical ‘executive’ tasks, such as the Wisconsin Card Sorting Test (WCST) and Verbal Fluency, frontal deficits were entirely explained by fluid intelligence. However, on a second set of frontal tasks, deficits remained even after statistically controlling for this factor. These tasks included tests of theory of mind and multitasking. As frontal dysfunction is the most frequent cognitive deficit observed in early Parkinson's disease (PD), the present study aimed to determine the role of fluid intelligence in such deficits.</jats:p></jats:sec><jats:sec id="S0033291712000451_sec_a002"><jats:title>Method</jats:title><jats:p>We assessed patients with PD (<jats:italic>n</jats:italic>=32) and control subjects (<jats:italic>n</jats:italic>=22) with the aforementioned frontal tests and with a test of fluid intelligence. Group performance was compared and fluid intelligence was introduced as a covariate to determine its role in frontal deficits shown by PD patients.</jats:p></jats:sec><jats:sec id="S0033291712000451_sec_a003" sec-type="results"><jats:title>Results</jats:title><jats:p>In line with our previous results, scores on the WCST and Verbal Fluency were closely linked to fluid intelligence. Significant patient–control differences were eliminated or at least substantially reduced once fluid intelligence was introduced as a covariate. However, for tasks of theory of mind and multitasking, deficits remained even after fluid intelligence was statistically controlled.</jats:p></jats:sec><jats:sec id="S0033291712000451_sec_a004" sec-type="conclusion"><jats:title>Conclusions</jats:title><jats:p>The present results suggest that clinical assessment of neuropsychological deficits in PD should include tests of fluid intelligence, together with one or more specific tasks that allow for the assessment of residual frontal deficits associated with theory of mind and multitasking.</jats:p></jats:sec>

Inter-individual cognitive variability in children with Asperger's syndrome

“…Correlation analyses revealed that FI was linked to cognitive flexibility and processing speed only for children with AS. Our data are consistent with recent studies suggesting that FI is a substantial contributor to classical EF tasks (such as TMT) in neurological patients (Roca et al, 2010, 2012). However, this effect cannot be attributed to a positive correlation between FI and all frontal functions.…”

“…However, this effect cannot be attributed to a positive correlation between FI and all frontal functions. In the present study, ToM was not correlated with FI, as reported elsewhere in the literature (Roca et al, 2010, 2012). …”

“…In addition, we hypothesize that MCSA will demonstrate varying patterns of cognitive strengths and weaknesses within individuals and that such variation will be absent in group-comparison analysis. Finally, given that FI has been associated with the cognitive profile of AS (Soulieres et al, 2011) and affords substantial contributions to frontal lobe functions (Duncan et al, 1995; Roca et al, 2010, 2012), we expect that individual differences in FI will partially influence the cognitive profile of AS children.…”

Theory of Mind and Its Neuropsychological and Quality of Life Correlates in the Early Stages of Amyotrophic Lateral Sclerosis

“…Some evidence supports a stronger association between executive functions and “fluid intelligence,” both involving mainly dorsolateral prefrontal networks (Roca et al, 2012), in contrast to ToM processes, hypothesized to be probably more dependent from medial prefrontal networks, especially with regard to the affective subcomponent (Shamay-Tsoory et al, 2005, 2006; Xi et al, 2011; Bertoux et al, 2016). However, more recently, Burke et al (2016b) demonstrated a significant impairment of ET, as a measure of affective social cognition, in ALS patients with executive dysfunctions compared to healthy subjects.…”

The relationship between executive functions and fluid intelligence in euthymic Bipolar Disorder patients

“…In this regard, multiple studies have shown that fluid intelligence deficits are responsible for the deficits observed in classical executive tests in different neurological and psychiatric conditions. Data from different clinical groups, including patients with frontal lobe lesions (Roca et al, 2010), Parkinson's disease (Roca et al, 2012), Frontotemporal Dementia (Roca et al, 2013), and Schizophrenia (Roca et al, 2014), have consistently shown that after factoring out the effects of g , no differences between patients and controls remain for classical executive tests, such as the Wisconsin Card Sorting Test (WCST), Verbal Fluency, and Trail Making Test B (TMTB). On the contrary, other frontal tests, including tests of multitasking and of social cognition, are not explained by differences in g. This discordance has been attributed to the fact that those multitasking and social cognition tasks reflect anterior prefrontal deficits rather than the dorsolateral deficits associated with g and classical executive deficits (Roca et al, 2010).…”