Treatment with deep brain stimulation improved motor function and quality of life, but depression scores increased after 1 year, based on data from 20 adults.
Subthalamic nucleus deep brain stimulation (STN-DBS) has emerged as an effective treatment for Parkinson’s disease symptoms, with evidence supporting improved motor symptoms and quality of life, wrote Francesca Mameli, PsyD, of Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, and colleagues.
However, the effect of STN-DBS on personality in Parkinson’s disease (PD) has not been well investigated they said.
In a study published in Neuromodulation, the researchers reviewed data from 12 women and 8 men with PD who underwent bilateral STN-DBS.
Depression was assessed via the Montgomery-Asberg Depressive Rating Scale (MADRS), personality characteristics were assessed via the Minnesota Multiphasic Personality Inventory–2 (MMPI-2), and motor disabilities were assessed via UPDRS-III-Motor. The motor disabilities score was obtained in medication on and medication off conditions; the off condition followed a 12-hour overnight withdrawal of dopaminergic medication. Quality of life was assessed via the Parkinson’s Disease Questionnaire–8 (PDQ-8).
After 12 months, scores on the MMPI-2 were significantly higher on the D subscale, increased from a baseline mean of 56.05 to a 12-month mean of 61.90 (P = .015).
Other MMPI-2 scales showing significant increases included the DEP scale, LSE scale, WRK scale, and TRT scale. No differences appeared between male and female patients.
No significant changes occurred from pre-DBS baseline to the 12-month follow-up in MADRS scale assessment, with mean scores of 8.18 and 9.22, respectively.
A 40% improvement in UPDRS measures of motor function occurred among patients in the “medication-off” condition, although there was no significant change following DBS in the medication-on condition, the researchers said. Among 18 patients with PDQ-8 assessments, quality of life scores were significantly higher at 12 months’ post DBS compared to baseline pre DBS (40.15 vs. 30.73, P = .011).
The researchers also examined the relationship between the total electrical energy delivered (TEED) and the occurrence of personality trait shift. In the TEED analysis, “only the energy on the right side was inversely correlated with the changes in depression,” they wrote.
“Because of the complexity of psychiatric phenomena, it would be advisable to take a cautious approach by including psychiatric evaluation by interview for a better selection of patients who score close to the pathological cutoffs in MADRS and MMPI-2,” the researchers wrote in their discussion.
The study findings were limited by several factors including the small sample size, lack of data on the prevalence and severity of apathy, the use of scales based on self-reports, and inability to control for all factors that might affect depressive traits, the researchers noted. In addition, more research is needed to explore the correlation between TEED and personality trait changes, they said.
However, the results support the value of DBS in PD, but emphasize the need to manage expectations, they emphasized. “Expectations should never be unrealistic, and the caring team should ensure not only that patients fully understand the risks and potential benefits of the DBS but also that it will not stop the neurodegenerative progression of the disease,” they said.
The study was supported in part by the Italian Ministry of Health. The researchers had no financial conflicts to disclose.