Home > Uncategorized > What is Parkinson’s Disease Dementia?

What is Parkinson’s Disease Dementia?

Image courtesy Imagerymagestic @ http://www.freedigitalphotos.comIt is estimated that nearly 2 percent of those individuals over the age of 65, or close to 1 million Americans, have Parkinson’s Disease. It can also occur in younger persons.  Between 50 and 80 percent of those persons will eventually develop dementia symptoms.  (1)  It appears to be more common in men than in women. (2)  The disorder is associated with abnormal microscopic deposits, made up primarily of alpha-synuclein, known as Lewy bodies.  This particular protein is also found in healthy brains, however their function is not fully understood.

In the early stages of Parkinson’s Disease, the parts of the brain that are affected include those which control movement, and early symptoms include tremors, stiffness in the muscles, a shuffling gait, stooped posture, difficulty initiating movement, and a frozen facial expression.  As these changes in the brain spread, they can begin to affect memory and the ability to pay attention, as well as judgement and reasoning ability. (1)

Symptoms of PDD include a progressive deterioration of thinking and reasoning.  The following characteristics can also be present:

  • Changes in memory, concentration, and judgment
  • Loss of decision-making ability
  • Inflexibility in adapting to changes
  • Trouble interpreting visual information
  • Muffled speech
  • Visual hallucinations
  • Delusions, or paranoid ideas
  • Depression
  • Irritability and anxiety
  • Sleep disturbances, including excessive daytime drowsiness and rapid eye movement (REM) sleep disorder
  • Distractibility
  • Slowed thinking
  • Disorientation in familiar surroundings
  • Problems learning new material
  • Difficulty putting a sequence of events in the correct order
  • Problems using complex language and interpreting the language of others
  • Lack of motivation (1, 2, 3)

It is widely believed that PDD and Dementia with Lewy Bodies (DLB) are both associated with a disordered processing of the alpha-synuclein proteins within the brain, albeit different expressions of that process.  In actuality, the two disorders were once considered to be the same, however in recent years research has shown that they are more likely two separate entities.  The two disorders are differentiated primarily by identifying when particular symptoms develop.

Individuals who exhibit motor symptoms first, with dementia symptoms only developing as much as 10 to 15 years later (although sometimes as soon as a year later), are said to have PDD. (2)  Those who show an impairment in cognition first, with motor symptoms showing up later, are more commonly diagnosed as having DLB.  (Although occasionally those with DLB first demonstrate motor and cognitive symptoms in about the same time frame.) (1)  In actuality, however, there is no real definitive method for diagnosing either disorder, as is the case with most forms of dementia.  Typically, a person who is newly diagnosed with Parkinson’s Disease is closely monitored for the development of cognitive symptoms, at which time his physician will order imaging studies and other tests to rule out other disorders such as stroke or brain injury.

There are other disorders which can cause symptoms similar to those found in PDD.  These include a vitamin B-12 deficiency or an underactive thyroid gland.  Symptoms which may point to the presence of a separate disorder include agitation, delusions, language difficulties, and early onset of memory problems.  If these are noted, the physician should rule out other disorders than PDD. (2)  It is also not uncommon for the person with PDD to show symptoms of Alzheimer’s Disease as well.

Some of the risk factors associated with PDD include:

  • Age of 70 years and older
  • A score of greater than 25 on the Parkinson’s disease rating scale (PDRS), a test that doctors use to check disease progression
  • Agitation, depression, disorientation or psychotic behavior when the person is treated with L-dopa
  • Exposure to severe psychological stress
  • Cardiovascular disease
  • Low socioeconomic status
  • Low education level
  • Severity of motor symptoms
  • The presence of Mild Cognitive Impairment (MCI)
  • Hallucinations in the absence of other dementia symptoms
  • Excessive daytime sleepiness
  • A particular pattern of symptoms known as postural instability and gait disturbance (PIGD), which includes “freezing” in mid-step, having difficulty initiating movements, shuffling, problems with balance, and falling. (1, 3)

The diagnosis of PDD is a complex task and one that should be undertaken by a team of professionals, and should be repeated periodically to determine the progression of the disease.  Procedures used will often include:

  • Answering questions and performing tasks specifically designed for the purpose
  • Neuropsychological tests to address the individual’s appearance, mood, anxiety level, and the presence of delusions and hallucinations
  • Assessment of cognitive processes, as well as reasoning and abstract thinking. (3)

Brain imaging studies, such as CT or MRI scans, are of little use in diagnosing PDD, unless they are used to differentiate it from other disorders such as stroke or depression. (3)

As with most forms of dementia, there is no treatment to slow the progression of PDD.  Treatment involves primarily the temporary alleviation of symptoms and the development of compensatory strategies.  It can involve the use of the following medications:

  • Cholinesterase inhibitors, which are commonly used for the treatment of disordered thought processes in Alzheimer’s.
  • Antipsychotic drugs to control behavioral issues, however these should only be used with extreme caution, as they can cause serious side effects in up to 50% of those with PDD.
  • L-dopa for the treatment of motor symptoms.  However, this can aggravate hallucinations and confusion in those with both PDD and DLB.
  • Antidepressants for the treatment of depression, of which the most common are selective serotonin reuptake inhibitors (SSRIs).
  • Clonazepam to treat REM sleep disorder. (1)
  • Anticholinergic drugs may help balance levels of dopamine and acetylcholine.  However, while these drugs may assist with movement problems, they may actually worsen memory loss.
  • Antidepressant or mood-stabilizing drugs may help with depression. (3)

Other treatments which may be of help for the individual with PDD include diet modification, such as a low-protein diet, as protein may affect the absorption of L-dopa. (3)  However, it is still important that the person take in enough calories and other nutrients.  The person with PDD should remain as active as possible, and even consider participating in physical therapy to provide assistance with mobility.  There will come a time when the person should no longer drive a vehicle, as both movement and cognitive problems may prevent quick reactions in some situations.  This is something that should be determined on an individual basis, with the guidance of a physician and other professionals.



1.  Alzheimer’s Association, 1/22/15

2.  Helpguide.org, 1/22/15

3.  emedicinehealth.com, 1/26/15


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