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Parkinson's Disease Dementia and Dementia with Lewy Bodies
Essentials
- Parkinson's disease dementia is associated with reduced attention and a decline in executive function skills as well as behavioural symptoms, such as reduced ability to take initiative.
- Dementia with Lewy bodies is characterised, in addition to cognitive symptoms, by recurring visual hallucinations, extrapyramidal symptoms as well as fluctuations in levels of alertness and cognitive function.
Parkinson's disease dementia
- The incidence of a progressive memory disease is 4-6 times higher in patients with Parkinson's disease than in the general population. Recent follow-up studies report a memory disease in 60-70% of patients with Parkinson's disease.
- Factors predisposing the patient to Parkinson's disease dementia (PDD) are: advanced age, severe parkinsonism with bradykinesia, postural and gait disturbance as well as an early occurrence of memory complaints.
- Criteria for PDD:
- diagnosis of Parkinson's disease for at least one year before the onset of progressive cognitive decline
- cognitive symptoms: impairment in attention, executive functions, visuospatial functions and memory
- behavioural symptoms: lack of initiative, changes in personality, hallucinations, delusions, excessive daytime sleepiness
- Pathology is based on the presence of cortical Lewy bodies, concomitant Alzheimer's disease (AD) changes, disorders of different neurotransmitter systems, or a combination of these processes. The cognitive symptoms correlate with a decline in the cholinergic system.
- Acetylcholinesterase inhibitors are the first-line treatment for PDD. Rivastigmine is the only drug in this group that has PDD as an official indication.
Dementia with Lewy bodies (DLB)
- In Parkinson's disease, Lewy bodies are typically found in substantia nigra and in the basal ganglia. In DLB, Lewy bodies are abundant in the cerebral cortex. Half of the patients with DLB also exhibit cerebral changes typical to Alzheimer's disease (AD).
- In individuals over 75 years, DLB affects about 5%, including the variants of the disease.
- The onset is slow, and the average duration of the disease is 8 years.
- Core features (two are essential for a diagnosis of DLB):
- fluctuating cognition with variations in attention and alertness
- recurrent detailed visual hallucinations
- extrapyramidal symptoms, i.e. features of parkinsonism (stiffness, slowness, gait disturbance, sometimes tremor).
- Features supportive of DLB:
- REM sleep behaviour disorder
- sensitivity to antipsychotics
- reduced dopamine transporter binding in the basal ganglia.
- Memory impairment is not typical in the early stages. An early progressive decline in episodic memory with coexisting DLB features is suggestive of concomitant Alzheimer's disease (DLB/AD).
- These patients are sensitive to antipsychotics, and even small doses may cause confusion and inability to walk.
- It may be possible to control visual hallucinations and confusion with second generation antipsychotics (clozapine, risperidone, quetiapine).
- Acetylcholinesterase inhibitors (donepezil, galantamine, rivastigmine Cholinesterase Inhibitors for Lewy Body Dementia) have been shown to be useful for the behavioural symptoms and attention disorders of DLB. Despite their efficacy, acetylcholinesterase inhibitors are not licensed for use in DLB. On the other hand, AD with features of DLB is an official indication for acetylcholinesterase inhibitors. The diagnosis is in this case DLB/AD.
- Physiotherapy and walking exercises must be initiated early to maintain mobility.
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