Neuroscience Week 4: Neurodegenerative Disorders Flashcards
the common theme of neurodegenerative diseases
- abnormal aggregation of proteins
- aggregates are resistant to proteases
- neuronal death and propagation of abnormal proteins
Disease table
Temporal progress of Alzheimer’s
Alzheimer’s Stages: Mild cognitive impairment duration
7 years
Alzheimer’s Stages: Mild cognitive impairment disease is found in?
medial temporal lobe
Alzheimer’s Stages: Mild cognitive impairment symptoms
- short-term memory loss
- Forgetfulness
Alzheimer’s Stages: Mild Alzheimer’s duration
2 years
Alzheimer’s Stages: Mild Alzheimer’s Disease is found in
medial temporal lobe and spreads to lateral temporal and parietal lobes
Alzheimer’s Stages: Mild Alzheimer’s symptoms
6 listed
- reading problems
- poor object recognition
- poor direction sense
- language deficits
- math deficits
- motor skill loss
Alzheimer’s Stages: Moderate Alzheimer’s duration
2 years
Alzheimer’s Stages: Moderate Alzheimer’s disease is found in?
spreads to frontal lobe
Alzheimer’s Stages: Moderate Alzheimer’s Symptoms
6 listed
- poor judgment
- impulsivity
- Short attention
- language deficits
- math deficits
- motor skill loss
Alzheimer’s Stages: Severe Alzheimer’s duration
3 years
Alzheimer’s Stages: Severe Alzheimer’s disease is found in?
spreads to occipital lobe
Alzheimer’s Stages: Severe Alzheimer’s Symptoms
3 listed
- visual problems
- Hallucinations
- Mutism
The most common cause of dementia in the elderly?
Alzheimer’s disease
Second most common cause of dementia?
Vascular dementia caused by hypertension, atherosclerosis or vasculitis
Alzheimer’s common age of onset?
Rarely present before age 50 (if it does think familial secondary to mutations in presenilin-1 and 2, part of γ-secretase complex, 5-10% are familial)
about ~50% incidence in >/= 84 years of age
Alzheimer’s Timeline
5-10 years to mutism, immobility, and hallucinations
Down syndrome and Alzheimer’s Disease
Down’s syndrome patients have increased incidence because gene for amyloid precursor protein is in chromosome 21 and down syndrome is chromosome 21
Alzheimer’s Disease Pathophysiology
- Amyloid precursor protein is normally cleaved by α and γ secretases producing a harmless soluble protein
- If the protein is cleaved by β secretase and then cleaved by γ secretase which generates large Aβ peptide (pathologic)
- β-amyloid deposition could be one of the triggers for Alzheimer’s Disease and lead to kinase activation which can phosphorylate Tau leading to microtubule disassembly
- Tau when hyperphosphorylated dissociates from microtubules and translocates from axons to the soma
- The clinical symptoms of Alzheimer’s disease correlate with Tau rather than β -amyloid
- Tau becomes sequestered causing neurofibrillary tangles
- Degeneration of cholinergic neurons in nucleus basalis of Meynert
Alzheimer’s Disease Treatment lecture
- Donepezil acetylcholinesterase inhibitor to increase cholinergic levels
- Memantine NMDA antagonist to prevent cell death
Alzheimer’s Disease forms
Sporadic form is the most common
APoE-2 reduces risk
ApoE-3 intermediate risk
ApoE-4 increases risk
Alzheimer’s Disease Risk Factors
APoE-2 reduces risk
ApoE-3 intermediate risk
ApoE-4 increases risk
These are cholesterol transporting proteins the relation to Alzheimer’s disease is not fully understood
The clinical symptoms of Alzheimer’s disease correlate with?
Tau burden rather than β-amyloid
CTE AKA
Chronic traumatic encephalopathy
Chronic traumatic encephalopathy also presents with?
Neurofibrillary tangles
Tau when hyperphosphorylated dissociates from?
- Microtubules
- when Tau is phosphorylated it dissociates and the microtubules become unstable and disassemble
- Tau becomes sequestered in neurofibrillary tangles
Alzheimer’s Disease Macroscopic pathology
- Cortical atrophy (narrowing of the gyri, widening of the sulci) in advanced AD
- Cortical atrophy and hydrocephalus ex vacuo (dilation of ventricles) in AD from the loss of neural tissue surrounding them
Normal brain comparison to Alzheimer’s Brain
Alzheimer’s Disease Microscopic pathology
- plaques contain a central core of amyloid and a surrounding region of dystrophic neurites
- stain is Bielschowsky Silver stain
- or antibodies specific for Tau
- intracellular filamentous inclusions composed of hyperphosphorylated Tau