1st February 2024

Parkinson’s disease dementia

Background

This is a rare form of dementia. It is due to progressive neurodegenerative cognitive decline, which constitutes approximately around 2% of all cases of dementia worldwide. Patients with Parkinson’s disease have a higher chance of dementia, although almost 2/3rd do not suffer from dementia. It is a condition characterised by deterioration of cognition and day-to-day tasks. 

It is generally characterised by difficulties in thinking and concentration. They usually present with difficulties in communication (speech and language) and executive functioning.

It is a part of dementia with Lewy bodies. One of the entities is Parkinson’s disease dementia, while the other is Lewy Body dementia. 

Epidemiology

• Like Alzheimer’s dementia, this is a common neurodegenerative illness
• It is seen similarly in both sexes.
• It is a disease of middle-aged and older people.
• It constitutes 2% of all cases of dementia worldwide

Pathophysiology

Lewy body accumulates in vulnerable sites of the central nervous system. It contains a protein called alpha-synuclein. The alpha-synuclein is seen in Alzheimer’s dementia as well. There is also a deficiency of Acetylcholine.

Depending on the deposition of the Lewy body, they can be predominantly Nigral disease, limbic disease or diffuse neocortical disease.

Parkinson’s disease dementia is diagnosed based on the timing of cognitive difficulties and motor symptoms. If dementia was present at the onset of symptoms or within 1 year of motor symptoms, then it is Lewy Body dementia. However, if someone has had Parkinson’s dementia or if they have had motor symptoms for at least 1 year and following that, if they develop memory difficulties, it is diagnosed as Parkinson’s disease dementia.

Risk factors

• No specific risk factors 
• Men and women are equally affected
• More likely to run in families
• The presence of hallucinations in a person without dementia, excessive daytime sleepiness and postural instability can increase the chances of dementia with Parkinson’s disease

Clinical features

1. Core clinical symptoms
   • Loss of memory- slowed thinking- poor concentration (This makes it difficult to make decisions, judgement and planning activities. It also makes one to do daily activities like dressing, grooming or cleaning difficult)
   • Recurrent visual hallucinations
   • Rapid eye movement and sleep behavioural disorder
   • Spontaneous motor signs of Parkinsonism
     • Bradykinesia
     • Resting tremor
     • Rigidity
2. Supportive clinical features
   • Excess daytime sleeping and insomnia
   • Severe sensitivity to antipsychotics
   • Anosmia
   • Mental Health problems- Depression, Anxiety, Apathy, Delusions
   • Irritability and agitation
   • Postural instability and repeated falls
   • Autonomic disturbances- Low BP, urological disturbances, constipation, syncope

Evaluation

• Very similar to Alzheimer’s dementia. Basic screening for memory problems
• EEG, polysomnography

Management

1. Treatment is mainly symptomatic
2. It is pertinent to get the diagnosis accurately so the right symptomatic treatment and support can be offered. Hence, the importance of detailed collateral history and investigations.
3. Medications used for visual hallucinations can worsen Parkinson’s, and treatment offered for Parkinson’s symptoms can worsen psychosis. Moreover, Neuroleptic sensitivity can add to the difficulty of offering limited medications.
4. Non-pharmacological treatment should be used in the first instance.

Bio

• Antipsychotics should be avoided as much as possible. Non-pharmacological approach such as comfortable surroundings and environment, adequate lighting, appropriate visual and hearing aids and managing other problems like dehydration, pain, infections, etc., is essential.
• The rest of the treatment is like Lewy Body dementia
• Consider antipsychotics, prn Benzodiazepine for Behavioural and Psychological symptoms of Dementia, weighing the pros and cons of antipsychotics and the physical health.
• Symptomatic treatment of anxiety and depression

Psycho

• The treatment is like Lewy Body dementia

Social

• The treatment is like Lewy Body dementia

Prognosis

Parkinson’s disease dementia is a progressive illness, and it progresses faster than Alzheimer’s dementia. Mortality is associated with complications such as swallowing problems and poor nutrition. Dysphagia and mobility issues can worsen aspiration and pneumonia. Mobility problems can lead to frequent falls and injuries.

People with a diagnosis live for less than 5 years or so approximately following the diagnosis. 

References

• Rongve, A. and Aarsland, D. (2020). The Lewy body dementias: Dementia with Lewy bodies and Parkinson’s disease dementia. academic.oup.com. [online] doi:https://doi.org/10.1093/med/9780198807292.003.0032.
• McKeith, I. (2007). Dementia with Lewy bodies and Parkinson’s disease with dementia: where two worlds collide. Practical Neurology, 7(6), pp.374–382. doi:https://doi.org/10.1136/jnnp.2007.134163.
• Aarsland, D., Batzu, L., Halliday, G.M., Geurtsen, G.J., Ballard, C., Ray Chaudhuri, K. and Weintraub, D. (2021). Parkinson disease-associated cognitive impairment. Nature Reviews Disease Primers, 7(1). doi:https://doi.org/10.1038/s41572-021-00280-3.
• Gibb, W.R.G. (1989). Dementia and Parkinson’s Disease. British Journal of Psychiatry, 154(5), pp.596–614. doi:https://doi.org/10.1192/bjp.154.5.596.
• Parkinson’s UK. (n.d.). Dementia. [online] Available at: https://www.parkinsons.org.uk/information-and-support/dementia
• Alzheimer’s Society. (n.d.). Parkinson’s disease. [online] Available at: https://www.alzheimers.org.uk/about-dementia/types-dementia/parkinsons-disease
• Alzheimer’s Disease and Dementia. (2019). Parkinson’s Disease. [online] Available at: https://www.alz.org/alzheimers-dementia/what-is-dementia/types-of-dementia/parkinson-s-disease-dementia#:~:text=Prevalence.%20The%20Parkinson%27s%20Foundation%20estimates%20that%20one%20million.