Week 6 - Alzheimer's and Dementias Flashcards
What is cortical dementia?
Preferential neuronal loss to cortical regions of the brain
What is the strongest predictor of Alzheimers?
Increase of age
What gender is more likely to develop Alzheimers?
Twice as many women as men
What is the average duration of Alzheimers?
8-10yrs, rarely survive more than 15
What stages precede the clinical symptomatic phases of Alzheimers?
Preclinical
Prodromal stages
Extend over two decades
What is the most common type of alzheimers?
Sporadic with a mean age of onset of 80yrs
What age is familial alzheimers onset?
<50yrs
What are the two key features of alzheimers?
- Targets specific regions of the brain
2. Targeted structures sustain massive cell loss
Where does preferential cell loss occur?
In cortical grey matter of the brain and limbic structures (hippocampus, amygdala)
Where is cortical atrophy most evident in the brain?
Frontal
Temporal
Parietal lobes
Dendritic arborisation causes neuronal loss in the frontal, temporal and parietal lobes. How much loss is there in these areas?
50%
What is a result of cortical thinning?
Ventricular enlargement
What brain areas reveal massive cell loss?
Parietal
Temporal
Hippocampus and structures leading to it
Amygdala
Specific subthalamic nuclei
Specific subcortical frontal areas (basal forebrain, olfactory areas)
What are the two primary findings by Alois Alzheimer which are still primary histological markers or DAT?
Amyloid/senile plaques
Neurofibrillary tangles
What are amyloid/senile plaques?
Clump like deposits in the neuropil (areas where there are large numbers of synapses) round aggregates of cellular trash.
Plaques contain beta-amyloid protein, as well are apolipoprotein E (ApoE)
What are neurofibrillary tangles?
Resemble entwined and twisted pairs of rope within cytoplasm of swollen cell bodies.
Tangles made of proteins (tau proteins)
Where are neurofibrillary tangles disproportionately concentrated?
Temporal-parietal areas
Hippocampus complex
Where are senile plaques concentrated?
Frontal and temporal regions of the brain
Hippocampal complex
What are some signs and symptoms that are usually associated with the onset of AD?
Failing recent memory
Depression and irritability
Occasionally a seizure
One or more language problems
Disorientation and confusion when a sudden disruption to work or social life occurs
In what stage of AD do primitive reflexes reemerge?
End stage AD
Describe the neuropathology of frontal-lobe dementia
Significant atrophy in the frontal and temporal lobes
Some changes in the parietal lobes
Subcortical structures unaffected
Cerebellum and brainstem unaffected
What are some characteristics of the initial stages of frontal-lobe dementia?
Silliness
Socially disinhibited behaviour
Poor judgement
Incontinence
What are some characteristics of middle stage frontal lobe dementia?
progressive apathy
Blunted affect
significant cognitive dysfunction
What are some characteristics of late stage frontal lobe dementia?
Mute
Display motor rigidity
Typically ends in terminal vegetative state
What is the prevalence of frontal-lobe dementia?
12% of all dementia cases
What is the duration of frontal-lobe dementia?
2-17 years
What is huntington’s disease?
Progressive subcortical dementia
Rare
Linked to gene ITI5 on chromosome 4
When does onset of huntington’s disease usually occur?
30-40yrs of age
How many years can a person survive with huntington’s disease?
10-2- years following onset
Always fatal
What is the primary neuropathalogical change in huntington’s disease?
Bilateral deterioration of the caudate nucleus
white matter structures
cerebellum
What is the caudate nucleus?
Component of the basal ganglia
Involved in timing, ordering, and sequencing of movement patterns
What is multi-infarct (vascular) dementia?
Second largest type of dementia
Results from multiple infarction of brain tissue, from repeated strokes or blockages to blood vessels
Can present with either subcortical features, cortical features or a combination of the two
How does multi-infarct dementia differ from AD?
Onset it acute and rapid
History of risk factors for stroke
Focal neurological signs consistent with focal brain damage
Better memory performance than with AD
Reduced verbal production
etc
What are the 4 types of Creutzfeldt-Jakob disease (CJD)?
- Sporatic
- Variant
- Familial
- Iatrogenic
What is the most common type of Creutzfeldt-Jakob disease?
Sporadic
What type of Creutzfeldt-Jakob disease occurs due to cross species infection via consumption of tainted meat containing neural tissue?
Variant
What is familial Creutzfeldt-Jakob disease?
Extremely rare familial variant of CJD only found in a handful or families, results in fatal insomnia
What is Iatrogenic Creutzfeldt-Jakob disease?
Humans can transmit CJD to each other via transplants of affected neuronal tissue, corneal transplants or contamination via medical procedures
What is a conseuqnce of Creutzfeldt-Jakob disease?
Astrogliosis appears as a result of glia filling areas following death of neurons
