Parkinson’s disease: a review of non-motor symptoms

Abstract

Parkinson’s disease (PD) is a neurodegenerative disorder resulting from degeneration of the substantia nigra and the dopaminergic nigrostriatal pathway. Most treatments are geared toward the management and relief of motor symptoms in Parkinson’s patients; however, as the disease progresses, various complications can be observed. Non-motor symptoms (NMS) may arise simply from the disease itself and are highly destructive to quality of life. These symptoms include mood disorders, cognitive dysfunction, pain, sensory dysfunction, and dysautonomia. Though it is undisputed that many NMS may appear years or even decades prior to the clinical diagnosis of PD, the focus of this review will be the overt motor phase of the condition. As such, the focus of this paper is to review the major NMS found in PD patients status post-diagnosis, their etiology, as well as treatment options available for the individual NMS.

Keywords:

• cognitive dysfunction
• mood disorders
• non-motor symptoms
• pain
• Parkinson’s disease
• quality of life
• sensory dysfunction

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Considering their serious impact on quality of life of patients, it is time to broaden the conversation of Parkinson’s disease (PD) therapy to include debilitating non-motor symptoms (NMS).

• As many NMS may precede the onset of PD by years or decades, such as hyposmia, REM sleep disorder, constipation, depression, excessive day time sleepiness, fatigue, pain, and erectile dysfunction (ED), it may be prudent to include a screening tool for patients with common predictive mood, autonomic, cognitive, or sensory disturbances.

• This would be especially necessary for patients with a positive family history for PD, or with other positively correlated co-morbid conditions.

• Bedside scales for evaluation of NMS such as the NMS Questionnaire may be useful in assessing the burden of NMS in Parkinson’s patients.

• Apart from remaining observant of such deficits themselves, clinicians must educate the patient and their family to help treat and reduce the impact of these symptoms. Regardless, education of both clinicians and patients will be a crucial factor in redefining the management of patients with PD, as will be further research to understanding the neurophysiology.