Consider Nonmotor Symptoms for Diagnosis of Parkinson's?

January 18, 2013

Nonmotor symptoms are common in patients with early Parkinson's disease, and they should be considered in the diagnosis and management of the condition, the authors of a new study suggest.

The study, published in the January 15 issue of Neurology, was conducted by a team led by Tien K. Khoo, MD, Newcastle University, Newcastle upon Tyne, United Kingdom.

Dr. Khoo, who is currently working at Griffith University, Queensland, Australia, explained to Medscape Medical News that nonmotor symptoms are often not recognized as being related to Parkinson's disease.

"Specialists are normally aware of them, but nonspecialists, family doctors and patients are often unaware that Parkinson's can include non motor symptoms."

He noted that nonmotor symptoms are known to occur in established Parkinson's disease, but their frequency early on in the condition has not been extensively studied.

Dr. Khoo and colleagues therefore compared the frequency of nonmotor symptoms in a group of 159 patients with newly diagnosed Parkinson's and in a group of 99 healthy age-matched controls.

Participants were screened with the Non-motor Symptom Questionnaire. Other assessments included measures of motor disability (Movement Disorders Society–revised Unified Parkinson's Disease Rating Scale), disease severity (Hoehn & Yahr staging), depression (Geriatric Depression Scale), and global cognitive function (Mini-Mental State Examination and Montreal Cognitive Assessment).

Results showed that the group with Parkinson's reported a significantly more nonmotor symptoms compared with controls (mean, 8.4 vs 2.8).

The most commonly experienced nonmotor symptoms in this group were excessive saliva, forgetfulness, urinary urgency, hyposmia (lack of ability to smell), and constipation.

Patients with more motor disability and those with the postural instability/gait subtype experienced more nonmotor symptoms.

"We found that 17 of 30 nonmotor symptoms screened for were more common in Parkinson's patients than in controls. These nonmotor symptoms can have a detrimental effect on quality of life," Dr. Khoo noted.

Earlier Diagnosis Key

He added that nonmotor symptoms can occur very early in the course of Parkinson's disease, often before the formal diagnosis of the condition. But these nonmotor symptoms are often overlooked, and this can delay diagnosis.

"I think we must ask whether we are picking up these symptoms early enough. If patients manifest these nonmotor symptoms first, perhaps we could diagnose Parkinson's earlier. But that would mean redefining the way we diagnose the condition," he said.

Dr. Khoo explained that at present, recommended criteria for the clinical diagnosis of Parkinson's is primarily based on motor symptoms. The defining symptom is bradykinesia. The presence of other motor symptoms, such as rigidity, postural instability/gait disorder, unsteadiness, falls, or tremor, is required to further support the diagnosis. Additional supportive criteria are unilateral presentation, progressive worsening, and response to treatment.

"I would suggest that given the proven significance of nonmotor symptoms, that they should be given more weight in the diagnosis and management of the condition," Dr. Khoo remarked. If a patient presents with several of these nonmotor symptoms, as well as one or more motor symptoms, I think Parkinson's should be considered, especially as early diagnosis and intervention often results in a better quality of life."

Senior author David Burn, MD, is quoted in a press release issued by Newcastle University as saying: "Hopefully clinicians can use these findings to improve the treatment of Parkinson's disease. The earlier we can get a diagnosis the quicker treatment can start and patient's quality of life will improve."

In the paper, the researchers conclude that the wide range of nonmotor symptoms experienced by patients with Parkinson's underscores the multisystem nature of the condition from disease onset and could implicate dysfunction of other neurotransmitters, such as serotonin, noradrenaline, and acetylcholine. They suggest that these systems could represent future therapeutic targets.

The study was funded by a grant from the United Kingdom NIHR Biomedical Research Centre for Ageing and Age-related Disease. Dr. Khoo has received educational grants from Teva-Lundbeck, GSK, and UCB Pharma. He has also received honoraria for lectures organized by Teva-Lundbeck. Dr. Burn has received grants from Wellcome Trust and GlaxoSmithKline. He has received honoraria from Teva-Lundbeck and UCB in the past 2 years and acted as consultant for GSK and Archimedes.

Neurology. 2013;80:276-281. Abstract