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Start Over Author "Okonkwo O" Topic executive function
3 results on '"Okonkwo O"'

1. Atlas-based diffusion tensor imaging correlates of executive function.

Author

Nowrangi MA, Okonkwo O, Lyketsos C, Oishi K, Mori S, Albert M, and Mielke MM

Subjects
Aged, Anisotropy, Atlases as Topic, Diffusion Tensor Imaging methods, Female, Humans, Male, Neuropsychological Tests, Alzheimer Disease pathology, Alzheimer Disease psychology, Brain pathology, Cognitive Dysfunction pathology, Cognitive Dysfunction psychology, Executive Function
Abstract

Impairment in executive function (EF) is commonly found in Alzheimer's disease (AD) and mild cognitive impairment (MCI). Atlas-based diffusion tensor imaging (DTI) methods may be useful in relating regional integrity to EF measures in MCI and AD. Sixty-six participants (25 normal controls, 22 MCI, and 19 AD) received DTI scans and clinical evaluation. DTI scans were applied to a pre-segmented atlas and fractional anisotropy (FA) and mean diffusivity (MD) were calculated. ANOVA was used to assess group differences in frontal, parietal, and cerebellar regions. For regions differing between groups (p < 0.01), linear regression examined the relationship between EF scores and regional FA and MD. Anisotropy and diffusivity in frontal and parietal lobe white matter structures were associated with EF scores in MCI and only frontal lobe structures in AD. EF was more strongly associated with FA than MD. The relationship between EF and anisotropy and diffusivity was strongest in MCI. These results suggest that regional white matter integrity is compromised in MCI and AD and that FA may be a better correlate of EF than MD.

Published
2015
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2. White matter microstructural integrity and executive function in Parkinson's disease.

Author

Gallagher C, Bell B, Bendlin B, Palotti M, Okonkwo O, Sodhi A, Wong R, Buyan-Dent L, Johnson S, Willette A, Harding S, Ninman N, Kastman E, and Alexander A

Subjects
Aged, Anisotropy, Case-Control Studies, Diffusion Magnetic Resonance Imaging, Female, Humans, Image Processing, Computer-Assisted, Male, Middle Aged, Neuropsychological Tests, Brain pathology, Cognition Disorders etiology, Executive Function physiology, Nerve Fibers, Myelinated pathology, Parkinson Disease complications, Parkinson Disease pathology
Abstract

Recent studies suggest that white matter abnormalities contribute to both motor and non-motor symptoms of Parkinson’s disease. The present study was designed to investigate the degree to which diffusion tensor magnetic resonance imaging (DTI) indices are related to executive function in Parkinson’s patients. We used tract-based spatial statistics to compare DTI data from 15 patients to 15 healthy, age- and education-matched controls. We then extracted mean values of fractional anisotropy (FA) and mean diffusivity (MD) within an a priori frontal mask. Executive function composite Z scores were regressed against these DTI indices, age, and total intracranial volume. In Parkinson’s patients, FA was related to executive composite scores, and both indices were related to Stroop interference scores. We conclude that white matter microstructural abnormalities contribute to cognitive deficits in Parkinson’s disease. Further work is needed to determine whether these white matter changes reflect the pathological process or a clinically important comorbidity.

Published
2013
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3. Self-Control and Exercise: A Review of the Bi-Directional Relationship

Author

Boat, R, Cooper, SB, Okonkwo, O, and van Praag, H

Subjects
self-regulation, Ego depletion, business.industry, Cognitive engagement, media_common.quotation_subject, Physical fitness, strength model of self-control, Review, physical performance, Self-control, shifting priorities model, Executive function, Physical performance, Exercise performance, Mental capacity, Trait, General Earth and Planetary Sciences, Psychology, business, ego depletion, General Environmental Science, media_common, Cognitive psychology
Abstract

Self-control has been defined as the mental capacity of an individual to alter, modify, change or override their impulses, desires, and habitual responses. In this review, we will discuss the bi-directional nature of the relationship between self-control and exercise. In brief, higher levels of trait self-control have been associated with greater exercise performance and adherence; whilst the depletion of state self-control has been shown to decrease performance and persistence on subsequent exercise tasks requiring self-control. In the opposite direction, long-term participation in exercise (and improved physical fitness) has been demonstrated to enhance self-control. Furthermore, an acute bout of exercise has been shown to enhance subsequent self-control, particularly when the exercise is of a moderate intensity and requires some degree of cognitive engagement. Throughout, when discussing each of these relationships, evidence will be drawn from other aspects of the review, where appropriate, to enhance our understanding of the observed effects. Finally, recommendations for future research will be made; including the importance of considering the bi-directional nature of the relationship, given that this has implications for our understanding of both self-control and exercise performance and adherence.

Published
2019
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