NEW ORLEANS—Patients with Parkinson’s disease have a greater degree of neuroticism and a stronger tendency to avoid harm than healthy controls do, according to research presented at the 64th Annual Meeting of the American Academy of Neurology. In young adulthood, Parkinson’s disease also is associated with engaging in, or wanting to engage in, fewer risky activities and with a greater desire for routine.
The findings are consistent with the existence of a distinct premorbid personality for patients with Parkinson’s disease, said Kelly L. Sullivan, PhD, a neuroepidemiologist at the University of South Florida in Tampa. The personality traits that a patient exhibits early in life may indicate his or her risk of developing Parkinson’s disease and help researchers understand the preclinical period of the disorder. The study results also “suggest that personality characteristics of patients with Parkinson’s disease are likely to be stable across the adult life course and are not a response to developing symptoms of the disease,” Dr. Sullivan told Neurology Reviews.
Assessing Participants’ Current and Previous Personality Traits
Dr. Sullivan and her colleagues sought to describe the current personality characteristics of patients with Parkinson’s disease, evaluate the correlation between these characteristics and indicators of patients’ personalities during early adulthood, and analyze the association between Parkinson’s disease and patients’ premorbid personality indicators in early adult life. The investigators examined a sample of 188 patients who were treated in the movement disorder or family medicine departments of an academic medical center. Of these patients, 89 had Parkinson’s disease, and 99 were controls.
The researchers assessed participants’ current personalities using standard tools such as the Neuroticism–Extroversion–Openness Five-Factor Inventory and the Temperament and Character Inventory. The investigators used patients’ reports of their participation in risky activities and behaviors, preference for routines, smoking, and alcohol consumption between ages 20 and 35 as indicators of their early-adult life personalities.
Dr. Sullivan and her group obtained Pearson correlations for associations of early-adult risky activities and routinization with current personality traits, controlling for the effects of age, sex, and education. They also used logistic regression analysis to examine associations between early-adult personality indicators and risk for Parkinson’s disease, again controlling for age, sex, and education.
An Emerging Picture of a Distinct “Parkinson’s Personality”
Current levels of neuroticism (odds ratio [OR], 1.05) and harm avoidance (OR, 1.07) were higher among patients with Parkinson’s disease than among controls. Both cases and controls showed consistent correlations between a preference for routines in early-adult life and current levels of extraversion, harm avoidance, neuroticism, and novelty seeking. Engaging or wanting to engage in risky activities as a young adult was significantly correlated with current levels of harm avoidance.
The Pearson correlation coefficient between harm avoidance and activity risks was –0.47 among patients with Parkinson’s disease and –0.42 among controls. The correlation coefficient between harm avoidance and a preference for routines was 0.47 for patients with Parkinson’s disease and 0.45 for controls.
The risk for Parkinson’s disease was associated with engaging in or wanting to engage in fewer risky activities as a young adult in the total sample (OR, 0.78) and among women (OR, 0.69). The risk for Parkinson’s disease also was associated with a greater preference for routine as a young adult among women (OR, 1.63). The association between risk taking as a young adult and Parkinson’s disease remained unchanged when the researchers included other personality indicators in the model, indicating that these are independent risk factors.
“The primary difference between our study and previous studies is in our approach to assessing premorbid personality,” said Dr. Sullivan. To try to reduce the possibility that personal interpretation or current situations might influence participants’ recollection of themselves, “we asked people if they participated in specific activities like riding roller coasters or speeding—very distinct events—when they were young adults and used these as indicators of their personality at that time,” she added.
“Many of our findings support findings from previous studies of personality and Parkinson’s disease. More research is needed to determine when the physiologic process of Parkinson’s disease begins and how best to mitigate the effects of the disease,” Dr. Sullivan concluded.
—Erik Greb
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