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Dementia in Parkinson's disease (PDD)

Neurodegenerative diseases

by Kurt Jellinger

General outline

While people with Parkinson’s disease have a higher risk of developing dementia than those without Parkinson’s disease, the majority will remain unaffected.

Parkinson’s disease is known as a movement disorder. The movement disorder is due to dopaminergic neurons mainly in the substantia nigra.

Motor symptoms always precede cognitive impairment by several years. Cognitive impairment is usually due to degenerative changes in limbic or neocortical structures, superimposed Alzheimer-type lesions and/or presence of cortical Lewy bodies, while degenerative lesions in subcortical neurotransmitter-specific loops are less important for the development of cognitive impairment.


Idiopathic parkinsonism plus dementia

Symptoms and course

Symptoms of dementia associated with Parkinson’s disease will vary from person to person. The most common are memory loss and the loss of the ability to reason and to carry out normal everyday tasks (planning, organising, solving problems). Patients may become obsessional, and there may be a loss of emotional control with sudden outbursts of anger or distress.

Medications may cause or aggravate visual hallucinations.

Language problems (slower speech, not word finding difficulties).

Symptoms often fluctuate so that the person will seem better or worse at different times. Gradually progressive, symptoms accumulate progressively.

Duration of the disease: 4-5 years. Parkinson’s disease plus dementia has shorter survival than Parkinson’s disease without dementia (average between 5 to 10 years).

Caregiver problems

With movement disorder, slowness in information processing (difficulty of communication) may lead to carer frustration.

Causes and risk factors

Abnormal aggregation of alpha synuclein in Lewy bodies. It is more than Lewy bodies accumulation (often associated with Alzheimer pathology).


Families with familial PD (Several chromosomes involved) There are inherited form of Parkinson’s disease associated with mutation on chromosomes xxx.


Parkinson’s disease is not RARE; however, only 10-30 % of the patients develop cognitive impairment / dementia. Prevalence 41:100,000

Diagnostic procedures

Nothing specific

Care and treatment

The movement disorder is treated by compounds augmenting dopamine transmission (dopaminergic substances and DA agonists). Medication may cause or aggravate hallucinations and psychotic symptoms. Antidementive drugs like in AD.

Ongoing research/Clinical trials Trials have been conducted on small patient samples demonstrating benefits of Cholinesterase inhibitors on cognitive ability.

Available services

European Parkinson’s Disease Association (EPDA) Lizzie Graham EPDA Liaison/Project Manager 4 Golding Road Sevenoaks Kent TN13 3NJ United Kingdom Tel/Fax: +44 (0)1732 457683

Parkinson’s disease associations provide services for the movement disorders but have less information on the cognitive problems associated with the disorder.

In a case of dementia, please refer also to Alzheimer’s disease associations.

Alzheimer Europe 145 Route de Thionville L- 2611 Luxembourg Tel: +352 / 29.79.70 Fax: +352 / 29.79.72

Alzheimer's Disease International 45-46 Lower Marsh London SE1 7RG United Kingdom Tel: +44 / 20 7620 3011 Fax: +44 / 20 7401 7351,


  • Jellinger et al: J Neural Transm 109 (2002) 329-339



Last Updated: Friday 09 October 2009


  • Acknowledgements

    This information was gathered in the framework of the European Commission financed project "Rare forms of dementia". Neither the European Commission nor any person acting on its behalf is responsible for any use that might be made of the following information.
  • European Union