Imaging of Alzheimer's and Parkinson's Diseases Flashcards
Describe the commonly used imaging techniques available to assist in the diagnosis of AD and PD Discuss the novel molecular imaging techniques being used in AD, and how these will be useful in patient management and therapeutic interventions Critically evaluate how these imaging techniques will change the classification and diagnosis of AD
State some pathological features of AD
Extracellular amyloid plaques, intracellular neurofibrillary tangles, neuritic plaques, astrocytosis
Where does plaque deposition in AD start?
Base of the forebrain
Where does neurofibrillary tangle deposition in AD start?
Hippocampus
Name a PET tracer for AD
11C-PIB (N-methyl[C-11]2-[4’-methylamino-phenyl]-6-hydroxyl-benzothiazole); 11F-FDG
What does 11C-PIB bind to?
Fibrillar amyloid
Name a part of the brain where fibrillar amyloid is not deposited in AD
Cerebellum
Define mild cognitive impairment
Impaired memory function for age and education but preserved general cognitive function
What percentage of mild cognitive impairment patients have converted to Alzheimer’s after 3 years?
80%
How does 11C-PIB uptake change as AD progresses?
No significant change - suggesting there is no correlation between amyloid load and cognitive performance
What does 18F-FDG detect?
Glucose metabolism
How does 18F-FDG uptake change as AD progresses?
Slight decrease
State the consensus guidelines for diagnosis of Lewy body dementia
Dementia before parkinsonism or within 12 months or parkinsonism and associated with hallucination and confusion
Describe the symptoms of Parkinson’s disease dementia
Impairment of short-term recall, attention, visuospatial function, and executive function, with personality and behavioural changes, confusion, and hallucinations
Describe the pathology associated with Lewy body dementia
Cortical Lewy bodies, neurofibrillary tangles, degeneration of subcortical nuclei (substantia nigra, nucleus basalis of Mynert, locus coeruleus)
Define subjective cognitive impairment
Perceived memory problems with normal performance on cognitive testing
Describe the stages involved in microglia activation
Ramified (R-stage) -> activation signal -> withdrawal (W-stage) -> transitional (T-stage)-> motile (M-stage) -> locomotory (L-stage)
Describe the actions of activated microglia
Protein expression, proliferation, cytokine secretion, transformation into macrophages
Name a PET tracer which binds to activated but not resting microglia
PK11195
Describe the relationship between microglial activation and AD
An increase in microglial activation over time correlates with a decline in cognitive function
What happens to CSF tau and amyloid-beta in AD?
CSF tau increases, whereas amyloid-beta decreases as it is sequestered in the brain
Name a PET tracer for tau
T807
Describe the relationship between tau load and MMSE performance
As tau load increases, MMSE performance decreases
