University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

498

Pages:

2
Author:

Mariam A.

Dementia with Lewy Bodies (DLB) Epidemiology  Second most common primary neurodegenerative disease associated with dementia; 10 – 25% of all cases.  Estimated prevalence of 0.7% aged >65 years old.  Mean age at presentation is 75 years old.  Increasing prevalence with age. Aetiology  Dementia with Lewy bodies.  Parkinson’s disease (PD).  Autonomic failure.  Lewy body dysphagia. Clinical features  Fluctuating cognition.  Recurrent well-formed detailed visual hallucinations.  Spontaneous parkinsonism. o Tremor at rest. o Bradykinesia. o Rigidity. o Loss of postural reflexes. o Flexed posture. o Freezing phenomenon.  Other or “supportive” features: o Repeated falls. o Syncope or transient loss of consciousness. o Severe autonomic dysfunction (e.g. HR, BP). o Depression.  Parkinson’s disease dementia differs in late onset of cognitive problems. Pathogenesis  Lewy bodies in neurons in several brain regions: o Brainstem. o Limbic. o Neocortical.  3 levels of involvement.  Significant loss of neurons known from substantia nigra and locus ceruleus. Histology  Macroscopic appearances are similar to AD.  Characterised by Lewy bodies. o Accumulation of α-synuclein (mainly) and ubiquitin within cytoplasm of cortical neurones. Difference between PD and DLB  Distribution of Lewy bodies: o PD: brainstem neurons (substantia nigra and locus coeruleus). o DLB: cortical neurons.  Clinical picture: o PD: slow movement, shuffling gait, rigidity and pill rolling tremor. o DLB: primary complaint of dementia. Overlap pathology  With AD: o About 80% of DLB patients have numerous diffuse plaques. o About 60% have NFTs in entorhinal cortex. o About 30% have florid AD type changes with many hippocampal and neocortical NFTs and high density of neuritic plaques.  With Parkinson’s disease (PD). o Lewy bodies are present in both. o In PD, Lewy bodies can spread to involve the cortical neurons and cause dementia. o PD with dementia if dementia occurs ≥1 year after PD. o DLB if dementia occurs <1 year after PD.  To complicate things further, dementia in some PD cases is related to co-existing pathological changes of AD (rather than cortical Lewy bodies).