Laterality of motor symptom onset in Parkinson's disease is both well-known and underappreciated. Treatment of disorders that have asymmetric pathological features, such as stroke and epilepsy, demonstrate the importance of incorporating hemispheric lateralization and specialization into therapy and care planning. These practices could theoretically extend to Parkinson's disease, providing increased diagnostic accuracy and improved treatment outcomes; however, laterality in Parkinson's disease has been largely ignored both clinically and in research. Additionally, while motor symptoms have generally received the majority of attention, non-motor features (e.g., autonomic dysfunction) also decrease quality of life and are influenced by asymmetrical neurodegeneration. Due to the laterality of cognitive and behavioral processes in the two brain hemispheres, analysis of hemibody side of onset can potentially give insight into expected symptom profile of the patient and allow for increased predictive accuracy of disease progression and outcome, thus opening the door to personalized and improved therapy in treating Parkinson's disease patients. This review discusses motor and non-motor symptoms (namely autonomic, sensory, visuospatial, language, and emotional dysfunction) of Parkinson's disease in respect to hemispheric lateralization from a theoretical perspective in hopes of providing a framework for future research and personalized treatment.

CitationDeVore BB, Harrison DW. Brain mechanisms in blood glucose mobilization and absorption: The role of the left and the right frontal regions in the regulatory control of blood glucose levels.

To determine the effects of self-reported anger expression style on cerebrally lateralized physiological responses to neuropsychological stressors, changes in systolic blood pressure and heart rate were examined in response to a verbal fluency task and a figural fluency task among individuals reporting either “anger in” or “anger out” expression styles. Significant group by trial interaction effects was found for systolic blood pressure following administration of verbal fluency [F(1,54) = 5.86, p < 0.05] and nonverbal fluency stressors [F(1,54) = 13.68, p < .001]. Similar interactions were seen for systolic heart rate following administration of verbal fluency [F(1,54) = 5.86, p < .005] and nonverbal fluency stressors [F(1,54) = 13.68, p < .001]. The corresponding results are discussed in terms of functional cerebral systems and potential implications for physiological models of anger. Given the association between anger and negative physical health outcomes, there is a clear need to better understand the physiological components of anger. The results of this experiment indicate that a repressive “anger in” expression style is associated with deregulation of the right frontal region. This same region has been shown to be intimately involved in cardiovascular recovery, glucose metabolism, and blood pressure regulation.

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Background: It has been evidenced that the outcome of a CVA patient differs as a function of the cerebral hemisphere that is damaged by the stroke, especially in terms of emotional changes. In contrast, the Bi-Hemispheric Model of Emotion posits that each hemisphere has its own emotional specialization. The current experiment tested the competing predictions of the two theoretical perspectives in a mixed sample of left cerebrovascular accident (LCVA) patients and right cerebrovascular accident (RCVA) patients using a Dichotic Listening task and the Affective Auditory Verbal Learning Test (AAVLT). Heart Rate (HR) and Pulse Oxygen Saturation (SpO2) were recorded as sympathetic measures. It was expected that the predictions of the Bi-Hemispheric Model would be supported. A series of mixed design ANOVAs were used to analyze the data. Material/Methods: Participants consisted of 21 patients grouped into either post-acute status left cerebrovascular accident (LCVA) or right cerebrovascular accident (RCVA). Tests included the The Dichotic Listening test, The Affective Auditory Verbal Learning Test (AAVLT), HR and Sp02 measurement using a Fingertip Pulse Oximeter and the Mood Assessment Scale for depression. Results: Results revealed that both groups exhibited decreased auditory detection abilities in the ear contralateral to CVA location. Additionally, CVA patients recalled significantly more positive words than negative or neutral words and exhibited a significant learning curve. LCVA patients exhibited a recency effect, while RCVA patients exhibited a heigh tened primacy effect. Findings from the HR and Sp02 measures suggested a parasympathetic response to emotionally neutral information as well as an impaired sympathetic response to emotionally negative information in RCVA patients. Conclusions: The results lend partial support to the hypothesis drawn from the Bi-Hemispheric Model of Emotion, as evidenced by the diametrically opposite effects in these groups, which reflects opposing cerebral processes.