Alzheimers biomarkers Flashcards
What test is used to identify adults at risk to AD?
Cognitive screening tests
What are 4 things that cognitive screening tests?
attention
spatial navigation
visuo-spatial orientation
short term working memory
conflict resolution
What brain region is spatial navigation involved in?
hippocampal & temporal involvement
What brain region is involved in visuo-spatial orientation?
parietal & limbic involvement
What brain region is involved in short term working memory?
Prefrontal involvement
What brain region is involved in conflict resolution?
cingulate & prefrontal involvement
What does Stroop colour & word tests assess?
Ability to inhibit cognitive interference
What are 3 pathophysiology biomarkers for AD?
amyloid beta deposition
tau
neurodegeneration
What is volumetric MRI?
Looks at enlarged ventricles in hippocampus to diagnose AD in the MCI stage -> loss of brain matter
What are 2 benefits of volumetric MRI?
Availability
non-invasive
What is a disadvantage of structural MRI?
Decreased hippocampal volume is not an AD-specific measure
What is positron emission tomography (PET)?
measures metabolic rates of glucose as a measure of neuronal activity
What areas of the brain does hypermetabolism occurs first in AD?
temporoparietal areas
What is a limitation of PET?
not widely available
expensive
What does amyloid PET measure?
Concentration of amyloid in CSF
What is the specific radiotracer used in amyloid PET
PiB -> binds insoluble amyloid fibrils
Where is substantial amyloid accumulation in AD located?
frontal cortex
neocortex
What are limitations of amyloid-PET?
short half life of PiB
low affinity for soluble oligomeric amyloid
What does aggregation of tau cause?
hyperphosphorylation of tau -> Paired helical fragments -> neurofibrillary tangles -> microtubule unstable -> dysfunctional neurons
What is an example of tau tracer?
18F-FDDNP
What does 18F-FDDNP bind?
extracellular amyloid-plaques & intracellular NFTs
What are limitations to tau tracers?
clinical validation still required
What does EEG have a strong correlation with?
MMSE scores (severity of dementia is linked to abnormal EEG)
What 3 c does EEG show AD?
Lower frequency rhythms
Reduction in alpha & beta bands
Increase in theta & delta
