I have an interest in working with patients with Parkinson’s Disease. This has led me to write a weekly Talking Tuesday blog for a fledgling PD support organization called the Parkinson’s Assistance, Network, Directory, and Alliance (P.A.N.D.A.). I find that conversations about non-motor symptoms (NMS) arise frequently among people with Parkinson’s. I’ve chosen an article on the topic for this third installment of our #SLPBloggers Research Blog project, which you can learn more about here.
Article: Khoo TK, Yarnall AJ, Duncan GW, et al. The spectrum of nonmotor symptoms in early Parkinson disease. Neurology 2013;80:276-281.
People with Parkinson’s often discuss NMS; however, very little research has been conducted to understand their role early in the disease process. The authors explain that dopaminergic medications are only partially responsible for NMS in people with PD. Sialorrhea (excessive saliva production), depression, insomnia, anxiety, apathy, and cognitive decline pose a challenge to a PD patient’s struggle to maintain quality of life.
The authors clearly state a two-part hypothesis:
(1) newly diagnosed people with PD experience NMS and
(2) people with the postural instability gait difficulty (PIGD) motor subtype have greater problems with cognitive, neuropsychological, and autonomic symptoms vs. those with non-PIGD subtypes.
The study is a Descriptive-Quantitative design with a study cohort comprised of 159 people newly diagnosed with PD and 99 healthy, age-matched control subjects. Clearly defined inclusion and exclusion criteria are present. Both groups were assessed by a physician, who obtained medical history, education, and pharmocologic information. Both groups also underwent a series of screenings to provide disease severity, motor disability, motor phenotype, cognitive function, and depression rating scales. NMS was measured using the NMSQuest screener. Statistical analyses were employed.
Inclusion/Participants: Subjects were drawn from newly identified cases of PD in a limited area in England during the period from June 1, 2009 through December 31, 2011, including 3-month “run-in” and “run-out” periods to insure capture of referrals that were within study parameters. Acceptable candidates were diagnosed with PD by a neurologist with a specialty in movement disorders and met criteria for diagnosis with ideopathic PD.
Inclusion/Controls: Age-matched to participants; healthy.
Exclusion/Participants: Excluded from the study were people diagnosed with PD outside study parameters defined above; lack of proficiency with English, which would have negatively impacted completion of questionnaires and other test instruments; memory impairment/dementia; Parkinsonian disorders e.g. drug-induced PD, vascular PD, atypical Parkinsonism e.g. progressive supranuclear palsy, multiple system atrophy, and corticobasal degeneration.
Exclusion/Controls: Caregivers, spouses, and others related to people with Parkinson’s were excluded from participation in the study.
The authors confirmed Part (1) of their hypothesis. People with PD experience NMS early in the disease process. Common complaints present more frequently in people with PD vs. healthy control subjects and include: sialorrhea/drooling, urinary urgency, hyposmia (reduced sense of smell), anxiety, and constipation. Regarding Part (2) of their hypothesis, the authors found no significant difference in cognitive/ neuropsychological symptoms when comparing people with PIGD subtype vs. tremor-dominant PD. Memory deficits is a common complaint; however, the study found this was also problematic in healthy control subjects (53.3% with PD; 41.4% healthy controls). Sialorrhea was the only symptom that was significantly more pronounced in PIGD phenotype vs. the tremor-dominant group. Age was not found to be a significant determinant of total NMS.
The authors provide a good discussion of and expansion on their findings. Effort was made to design the study in a way that discouraged bias, acknowledging that a design based on subjective reporting could limit reliability. The authors discuss areas of strength and weakness and also identify findings that could inform future research, e.g. the implication of PD as a disorder of multiple systems and the potential role of neurotransmitters other than dopamine.
All in all I thought this study well-done. It is relatively low on the evidence-base continuum but is strengthened by a decent cohort of subjects and controls. I found it informative. Non-motor symptoms negatively impact the quality of life with people with Parkinson’s Disease, and I hope to see more research along this line in the future.