April 14, 2021

Parkinson’s Disease Diagnosis

We discovered in Parkinson’s disease causes | Parkinson’s disease risk factors that there is currently no known definite factor or biological marker associated with Parkinson’s disease; meaning that Parkinson’s disease diagnosis does not rely on any one specific test. The situation is complicated by the fact that a person’s symptoms can be similar to, or caused by various other conditions or medications.


The process of Parkinson’s disease diagnosis will usually involve a neurologist:

  • Undertaking a review of the patients medical history.
  • Carrying out a neurological examination.
  • Performing a variety of tests including  blood, urine and brain scans.
Parkinson's Disease Diagnosis

Parkinson's Disease Diagnosis

The neurologist will aim to establish a symptom profile, which includes identifying:

  • When their symptoms begun.
  • The type of symptoms the patient has experienced.
  • How frequent the symptoms occur.
  • The factors that affect their symptoms.

Therefore, it is important for the patient to:

  • Keep a record of their symptoms and any medication they have been taking.
  • Reveal any significant life changes they have experienced.

To provided support and ensure the patient conveys all relevant information accurately, it is often advised that they are accompanied to their consultation by a friend or family member.

Although the possible symptoms of Parkinson’s disease can be extensive (see previous articles covering  4 Cardinal Symptoms,  Associated Symptoms and Neuropsychiatric Dysfunction), during the initial stages of evaluation, a neurologist will be particularly looking out for signs of:

  • Tremor at rest.
  • Slowing motion.
  • Rigidity.
  • Unilateral symptoms that improve significantly through using Levodopa.

To help in the process of Parkinson’s disease diagnosis and eliminate various other conditions, the neurologist will carry out a series of CT and MRI brain scans.

  • SPECT or PET scans help identify dopamine deficiency.
  • The use of Da TSCAN with SPECT imaging for patients exhibiting tremors (without other Parkinson’s signs) will probably become more commonly available in the future.

Brain changes observed with Parkinson’s patients include:

  • Lack of dopamine .
    Depending on the source of data, Parkinson’s symptoms do not normally show until 60-90% of dopamine function is lost.
  • Low norepinephrine levels.
    This may explain non-motor symptoms such as blood pressure regulation and fatigue.
  • Protein clumping and presence of Lewy bodies observed in autopsy.
    Parkinson’s Disease Dementia (PDD) is differentiated from Dementia with Lewy Bodies (DLB) by their differing symptoms profiles e.g. DLB is characterized by cognitive issues preceding motor related problems such as difficulty with walking. Early dementia i.e. within 2 years of exhibiting Parkinson’s clinical symptoms, is more likely due to DLB.

Parkinson’s Disease Misdiagnosis

Given the lack of a definite factor or biological marker, there does exist the potential for Parkinson’s disease misdiagnosis. Although the exact extent of the problem is not currently known, certain studies have suggested misdiagnosis is relatively common. If future studies confirm this to be true, it would indicate that many people would have been treated  for years or medicated  for the rest of their life erroneously. For example, certain studies have indicated that:

  • Incorrect initial diagnosis by a neurologists occurred in 24 – 35% of cases.
  • Where people were taking Parkinson’s disease drugs, re-evaluation of patients indicated:
    • Parkinsonism was only confirmed in 74% of cases.
    • Only 53% of patients had probable Parkinson’s disease.
    • 33+% of patients with tremors misdiagnosed as Essentail Tremors (ET), were typically found to have Parkinson’s disease.
    • 25+% did not benefit from the drugs being taken.
    • Up to 25% with tremor disorders were misdiagnosed as tremor dominant Parkinson’s disease.
    • Up to 20% with tremor dominant Parkinson’s disease were misdiagnosed as having other tremor disorders.
Following on Parkinson’s disease diagnosis, we will consider in the next article the various systems used to categorize Parkinson’s disease stages.