Year of Publication

2016

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Arts and Sciences

Department

Psychology

First Advisor

Dr. David T.R. Berry

Second Advisor

Dr. Suzanne C. Segerstrom

Abstract

Parkinson’s Disease (PD) is a common neurodegenerative disorder that attacks the basal ganglia and contributes to a range of motor, cognitive, and behavioral impairments (e.g., tremor, rigidity, and executive dysfunction). This dysfunction may contribute to self-regulatory impairment across several domains, including cognitive skills, thought processes, and emotion. Deep Brain Stimulation (DBS) is a neurosurgical procedure that allows for direct and reversible manipulation of brain activity in patients with PD. The procedure is growing in popularity and is commonly used as an adjunct or in some instances an alternative to dopaminometic medications. Preliminary studies suggest mild executive dysfunction follows DBS but as the literature is in its early stages, there is a need to examine further the range of executive deficits and self-regulatory impairment observed in PD following DBS.

In the present study, twenty-seven PD patients post-DBS completed a brief neuropsychological test battery and provided measures of heart rate variability (HRV). Patients also completed questionnaires regarding their ability to self-regulate emotions and thought patterns. Scores were compared to the patient’s pre-surgical performance as well as to a group of healthy older adults.

Results suggest DBS leads to significant declines in executive function (EF) and self-regulation (SR). Patients had significantly worse scores on neuropsychological tests of EF (i.e., phonemic fluency, semantic fluency, and working memory) when compared to their preoperative performance. Similarly, DBS patients had significantly worse scores than controls on measures of EF (i.e., verbal fluency, attention, mental flexibility) and verbal memory. With regard to physiological functioning, lower baseline HRV was linked to worse EF but fewer impulsive-compulsive behaviors in DBS patients. Correlations among measures of theoretically similar constructs (i.e., EF and SR) modest and variable, challenging the idea that SR in different domains depends on a common resource.

The results of the current study suggest that PD patients are prone to a variety of self-regulatory deficits, ranging from subtle to severe. They are likely to experience small declines in EF post-DBS that may contribute to these self-regulatory impairments. However, this research suggests that both the quantity and quality of impairment varies, and that the correlates of these deficits may be different between patients. Clinically, it is important for health care professionals working with PD to recognize the presence of self-regulatory deficits and to be aware of the potential obstacles that might arise from such impairments within a patient’s daily life.

Digital Object Identifier (DOI)

https://doi.org/10.13023/ETD.2016.400

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