Dementia Flashcards
what are normal, age-associated cognitive changes?
- difficulty retrieving words and names
- slower processing speed
- difficulty sustaining attention when faced with competing environmental stimuli
- learning something takes bigger effort
- no functional impairment
what is the definition of mild cognitive impairment (MCI)?
- memory complaint corroborated by an informant
- objective memory impairment for age and education
- preserved general cognition
- normal activities of daily living
- not demented
what is amnestic MCI?
memory loss not meeting criteria for dementia
- progresses to AD at risk of 10-15% per year VS 1-3% incidence in general population
- may be earliest phase of AD
- it’s a clinical diagnosis, as there’s no test for MCI
what is the DSM-IV diagnostic criteria for dementia (DSM-5 is neurocognitive disorder, mild/major)
- memory decline/impairment and at least one of the following:
- aphasia
- apraxia
- impaired executive function
- agnosia
- DSM5: decline in memory, complex attention, executive function, learning/memory, language, perceptual/motor, social cognition - cognitive deficits must impact social and occupational function
- major: patient incapable of independent living - diagnosis must be made in presence of clear sensorium
early onset AD
occurs between 30-60 yo
- rare, and familial in most cases
- single gene mutation:
- -1: abnormal presenilin 2
- -14: abnormal presenelin 1
- -21: abnormal amyloid precursor protein
late onset AD
most common form
- develops after age 60
- combination of factors is responsible (vascular, diabetic, etc)
- Xm 19: apolipoprotein E4 is implicated
what does AD look like grossly?
cerebral atrophy, especially affecting temporal, parietal, and frontal areas, with ventricular enlargement
- flat gyri, wide sulci
- hippocampus shrinks
what does AD look like microscopically?
- amyloid plaques (extracellular deposits of beta-amyloid peptide) associated with dystrophic neurites (neuritic plaques)
- A-beta deposits in cortical and leptomeningeal arteries and arterioles (amyloid angiopathy)
- neurofibrillary tangles and neuropil threads (filamentous intracellular inclusions of tau protein)
- granulovacuolar degeneration (GVD)
- Hirano bodies
what are the steps to forming the APP molecule?
pathologic cleavage by beta and gamma secretases
- creates 40 or 42 (seed, worse)
- creates neural network dysfunction, tau abnormalities, neurodegeneration, nt deficits, and memory impairment
what is the difference between neuritic plaques and diffuse plaques?
neuritic: larger, with dark brown center (represents 42 APP seed)
diffuse: smaller, don’t have brown center (40 APP)
what does cerebral amyloid angiopathy look like?
smooth muscle of vessels has been replaced by amyloid
-may cause hemorrhage and more vascular dementia
what is the major component of neurofibrillary tangles?
hyperphosphorylated tau (microtubule-associated protein) -dissociates from microtubules and assembles to form paired helical filaments, which are bundled together to form NFTs and neuropil threads (periphery of plaques)
describe what granulovascular degeneration and Hirano bodies are
nonspecific features of AD observed in hippocampi
-also in regular brains, so not important diagnostically
what is the difference between FTLD-Tau and FTLD-TDP?
- FTLD-Tau is Pick’s disease, and more common
- FTLD-TDP has no tau protein
both have profound anterior frontal and superior temporal knife-edge atrophy (parietal and occipital are spared)
-eccentric asymmetrical nuclei
what are vulnerable neurons in AD? the cytopathology?
hippocampus, entorhinal cortex, neocortex, basal forebrain cholinergic system
-NFT, neurites, A-beta deposition, and other cellular abnormalities
which are more diagnostic and which come sooner between A-beta plaques and tau proteins?
A-beta come sooner, but tau proteins are more diagnostic
what are AD risk factors?
- increasing age
- female
- FH of dementia, apolipoprotein E4 allele
- fewer years of education
- lower income and occupational status
- depression or other emotional illness
- head injury, post-operative delirium, alcohol abuse
- low folate, B12
- high plasma homocysteine
what are the 3 key features of AD?
- impaired cognition
- impaired function
- behavioral disturbances
what are early cognitive symptoms of AD?
- trouble keeping appointments
- difficulty finding words
- misplacing objects (unable to retrace steps)
what are early functional symptoms of AD?
- difficulty driving
- difficulty selecting appropriate clothes, or wearing same thing every day
- missing appointments
- problems at work
what are early behavioral symptoms of AD?
- subtle changes in personality
- social withdrawal
- depression
how does primary depression differ from dementia?
- less motivation during cognitive testing (dementia patients try very hard)
- express cognitive complaints that exceed measured deficits
- maintain language and motor skills
why is it important to diagnose AD early?
- rule out reversible causes
- initiate appropriate therapy
- enrollment for clinical trials
- advance directives and planning