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The non-motor symptoms

The non-motor symptoms of Parkinson’s refer to disorders which are not related to movement. The manifestations of non-motor symptoms are broad, consisting of psychiatric, sleep, autonomic and sensory disorders.

There are several causes of non-motor symptoms in Parkinson’s. Firstly, the non-motor symptoms can be due to Parkinson’s itself. For example, loss of sense of smell, depression, RMBD (one of the types of sleep disorders in Parkinson’splease refer to another article in the “Complications” section), fatigue, anxiety and constipation may precede the motor symptoms of Parkinson’s, and can be considered as part of the symptoms of Parkinson’s. Secondly, non-motor symptoms such as psychosis and low blood pressure, are occasionally caused by the side effects of the treatment of Parkinson’s. Lastly, some non-motor symptoms especially anxiety and depression occur as part of the non-motor fluctuations, i.e. the “off” period symptoms.

Apart from some non-motor symptoms which can precede the motor symptoms of Parkinson’s (as mentioned above), generally the non-motor symptoms become more frequent towards the advanced stage of Parkinson’s.

What are the non-motor symptoms?

a) Psychiatric disorders

These consist of psychosis, depression, anxiety and dementia.

b) Sleep disorders

Examples are insomnia and excessive daytime sleepiness. Sleep disorders are discussed further in another article in the “Complications” section.

c) Autonomic disorders

Examples are low blood pressure, excessive sweating, constipation and urinary disorders.

d) Sensory disorders

These consist of the following:

i)  Pain

Up to 38% of Parkinson’s patients experience pain that affects the side of the body where the Parkinson’s symptoms are more severe or have originated. This type of pain is typically described as constant “aching sensation” (which is different from the painful muscle cramp associated with foot dystonia, one of the motor complications), which is more common during the “off” periods. Treatment of the “off” periods can relieve the constant “aching sensation”.

A 62 year-old man has been diagnosed to have Parkinson’s for two years. He complained of stiffness, tremor and difficulty in movement on the left side of his body. He responded well to Ropinirole 2 mg three times a day.Recently, he started to have mild aching pain on the left upper and lower limbs, which was present the moment he woke up in the morning. He did not feel any tingling sensation or numbness. Initially, he was suspected to suffer from stroke. But relevant investigations, such as brain and neck scans and nerve studies, were normal.Following the increase in the dose of Ropinirole to 4 mg three times a day, his pain was relieved.


ii)  Loss of sense of smell

This has been long recognized as one of the early symptoms of Parkinson’s, which may precede the motor symptoms. In fact, certain diagnostic kits such as “smell test” had been developed as a method to diagnose early stage Parkinson’s.

iii) Impaired vision

Some Parkinson’s patients have complained of difficulty reading the newspapers even when their vision is normal. This visual disturbance is attributed to Parkinson’s itself.

Failure to recognize the non-motor symptoms

The non-motor symptoms are common in Parkinson’s. In fact, many Parkinson’s patients experience more than one non-motor symptoms. A study has shown that 59% of Parkinson’s patients had two or more non-motor symptoms, and 25% had four or more (Shulman LM, 2001). For some Parkinson’s patients, the non-motor symptoms can even be more disabling than the motor symptoms.

Despite being very common and disabling, the non-motor symptoms of Parkinson’s, especially the psychiatric complications, have received little attention till today. This is because of the lack of awareness of the non-motor symptoms, preoccupation with the motor symptoms, or both.

The non-motor symptoms are the neglected other half of Parkinson’s.


Despite contributing to severe disability and impaired quality of life (Chaudhuri KR, 2006), the non-motor symptoms of Parkinson’s are under-recognized and under-treated. In a study which was carried out on Parkinson’s patients who were seen at the clinics, even the Neurologists failed to recognize the presence of depression and anxiety more than half of the time, and failed to identify sleep disturbance in 40% of patients (Shulman LM, 2002).

Whenever Parkinson’s patients return to the clinic for review, the main focus of attention is the motor aspect of Parkinson’s. This is because Parkinson’s has been traditionally known to be a movement disorder which causes slowness of movement, body stiffness and tremor.

Due to its complexity (“wearing off” phenomenon, dyskinesia, “on” periods, “off” periods, “on and off” phenomenon, etc), treating the movement disorder in Parkinson’s alone may take up to 30 minutes of the clinic consultation time, leaving too little time for the doctors to enquire about the non-motor symptoms (especially the psychiatric disorders). In other words, the doctors, Parkinson’s patients and caregivers are often more preoccupied by the movement disorder, to the extent that the non-motor symptoms are overlooked.

Many people, including Parkinson’s patients,caregivers and even doctors, are more preoccupied with the movement disorder in Parkinson’s than the coexisting psychiatric disorders.

Even I myself once had this over-simplistic perception of Parkinson’s. Right from the day of graduation from medical school, until the early years of my medical practice as a Neurologist, I had always focused only on the movement disorder when dealing with Parkinson’s patients. But as I treated more and more Parkinson’s patients over the years, my priorities have gradually changed. Nowadays, I pay more attention to the non-motor symptoms of Parkinson’s. I have adopted a “50-50” strategy – half of my time is spent on managing the motor symptoms while the remaining half is spent on the non-motor symptoms.

Parkinson’s package – Most Parkinson’s patients “receive” the complete package, which consists of both the motor and non-motor symptoms.

In fact, I find that the non-motor symptoms of Parkinson’s are more challenging to treat compared with the movement disorder. With the rapid advances in Parkinson’s medications and brain surgery, managing the movement disorder is not really that difficult anymore.

In order to provide a more comprehensive and effective treatment of Parkinson’s, it is best to adopt a broader concept of this illness, i.e. Parkinson’s complex, a group of disorders consisting of motor and non-motor symptoms.

Treatment of non-motor symptoms

The occurrence of non-motor symptoms is not related to the dopamine deficiency in the brain. As such, many non-motor symptoms such as constipation, autonomic disorders, loss of sense of smell and psychiatric problems do not respond to Parkinson’s medications. The exception is non-motor symptoms that occur as part of the “off” periods such as pain, anxiety and depression, which can respond to Parkinson’s medications.

However, there are other types of medications which can improve non-motor symptoms such as depression, constipation, sleep disorders and urinary problems. The specific treatment of these non-motor symptoms is discussed in the relevant sections.

  • Even though the non-motor symptoms of Parkinson’s are common and disabling, they are under-recognized
  • The non-motor symptoms are due to Parkinson’s itself, the treatment and “off” period phenomenon
  • Some non-motor symptoms such as depression, anxiety and loss of sense of smell may precede the motor symptoms of Parkinson’s
  • Specific treatment is available for non-motor symptoms. However, the Parkinson’s medications are generally not effective in treating non-motor symptoms.



Chaudhuri KR, Healy DG, Schapira AHV. Non-motor symptoms of Parkinson’s disease: diagnosis and management. Lancet Neurol 2006; 5: 235-45.

Shulman LM, Taback RL, Bean J, et al. Comorbidity of the non-motor symptoms of Parkinson’s disease. Mov Disord 2001; 16(3): 507-510.

Shulman LM, Taback RL, Rabinstein AA, et al. Non-recognition of depression and other non-motor symptoms in Parkinson’s disease. Parkinsonism Relat Disord 2002; 8: 193–197.