April 9, 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.

Parkinson’s Disease Symptoms – Neuropsychiatric Dysfunction


As we learnt in Parkinson’s disease early symptoms, Parkinson’s symptoms can be categorized into the 4 Cardinal Signs, Associated Symptoms and  Neuropsychiatric Dysfunction.

Neuropsychiatric Dysfunction associated with Parkinson’s can be viewed in terms of a patient’s state of mental well-being, and possible issues related to Dementia.

Mental Well-Being

A Parkinson’s patients mental well-being can be affected by a reaction to the disease, chemical changes in the brain e.g. research indicates acetylcholine is linked to a person’s mental state and serotonin to one’s mood, or the side effects of medications used to manage the disease (therefore may not be due to dementia noted later). This can affect the patients daily life, relationships and ability to socialize significantly. Aspects of mental well-being include:

  • Behavior, personality and mood alterations:
    • Antisocial or becoming withdrawn.
    • Apathy.
    • Anxiety.
    • Depression.
    • Hallucinations and delusions occur in approximately 5% of patients.
    • Impulse control issues e.g. cravings.


  • Cognitive disturbances :
    • Decreased attention span.
    • Executive dysfunction (executive function deficit (EFD): Ability to plan and execute appropriate actions.
    • Impaired memory and recall
    • Reduced mental:
      • Agility.
      • Clarity. Often described as a ‘dullness/dull thinking’
      • Flexibility.
      • Slowness (Bradyphrenia) including slow response to questions.
    • Visuospatial difficulties including facial recognition.




  • Depending on the source of data:
    • Between 30-40% of patients will experience some degree of cognitive impairment and memory problems. Some research suggests this rises to 80% after 8-10 years of the disease.
    • Between 1/5 and 1/3 of Parkinson’s patients develop some form of Parkinson’s Disease Dementia (PDD). The figure commonly quoted is around 20%.
  • The rate of progression and severity of dementia varies considerably between individuals.
  • Parkinson’s Disease Dementia typically takes 10-15 years to develop from initial Parkinson’s diagnosis. It is therefore considered to occur towards the later stages of the disease.
  • Parkinson’s disease patients have a  4- 6X greater risk of developing cognitive impairment or dementia than the general population.
  • Various issues arise regarding Parkinson’s Disease Dementia including:
    • Significant symptoms noted above in Mental Well-Being.
    • Increased mortality rate.
    • Reduced quality of life for patient and increased burden for family and carers/caregivers.
    • Nursing home care more likely.
  • It must be remembered that dementia symptoms can be caused by a variety of unrelated conditions and medications e.g. Vit B12 deficiency, underactive thyroid gland, depression, Alzheimer’s disease.

GENERAL OVERVIEW OF DEMENTIA : Description-Assessment-Types


The next article will consider the fundamental question of What is Parkinson’s Disease ?