Chapter 7/17/18 - Aging and Cognition Flashcards
What did Baltimore’s study involve?
Longitudinal study of aging
2000+ people followed > 40 years
What did Baltimore’s study observe declines in?
Memory, visuospatial, verbal fluency, general IQ, in mid 60s
During the 3rd decade of life, what is observed?
Cells loss, synaptic loss (regional patterns!)
Which part of the brain is correlated with performance?
Hippocampal size
Which part of the brain is correlated with performance?
Hippocampal size
Some studies have found decreased brain activation during what?
Encoding and retrieval of information requiring self-initiated effort
When faces had to be learned, what was observed?
Less active frontal and temporal areas
Some studies reported higher activation levels though. What may this be the result of?
Effort
What are four other additional changes of CNS during aging?
- Motor skills - gait and stride
- Postural reflexes
- Sleep
- Brain weight decreases
What is loss with respect to sleep when aging?
Loss of stage 3,4, and REM sleep
More nocturnal waking
Brain weight decreases involves the loss of what?
- Neurons and neural connections
2. Enzymes that synthesize neurotransmitters (e.g. ChAT)
What are three ways to slow the effects of aging?
- Favourable environment
- Intellectually stimulating activities
- Having a partner with high I.Q.
What is a herb that is thought to decrease the occurrence of Alzheimer’s/dementia?
Ginkgo Biloba
What characterizes senile dementias?
Cognitive impairments and loss of memory that interfere with social/occupational function
What are some types and causes of senile dementias?
Cerebrovascular disease Lewy body dementia Parkinson's Alcoholism AIDS Syphilis Brain tumor, vitamin deficiency
What is the most common senile dementia?
Alzheimer’s Disease (40% of people over 80)
What are the initial symptoms of Alzheimer’s Disease? Later symptoms?
Initial: Loss of memory for recent events
Later: Complete cognitive decline (progressive)
What is observed through a PET scan for those with Alzheimer’s?
Overall decrease in brain activity (temporal and posterior parietal lobes)
Cell loss in frontal, temporal, and parietal lobe
What is observed through a PET scan for those with Alzheimer’s?
Overall decrease in brain activity (temporal and posterior parietal lobes)
Cell loss in frontal, temporal, and parietal lobe
Treatments for senile dementias depend on what?
Cause
Case history, physical, psychological work up
What can occasionally be seen through using CT and MRI?
Mediotemporal lobe abnormalities
What can be seen through using PET, SPECT, fMRI?
Decreased blood flow to parietal and temporal lobes
When can senile dementia be definitively diagnosed?
Autopsies
What are the three main characteristics of Alzheimer’s Disease?
- Senile plaques - B Amyloid
- Neurofibrillary Tangles - Tau
- Basal forebrain degeneration
What are the structural abnormalities observed with Alzheimer’s Disease? Hint: These areas regulate memory, attention, behaviour and emotions
1) Neocortex, entorhinal area, hippocampus, amygdala
2) Nucleus basalis, anterior thalamus, locus coeruleus, raphe nuclei
Where are signs of AD first noticed in?
Entorhinal cortex, then proceed to hippocampus
Changes can begin how many years before symptoms appear?
10-20
What begins to shrink as more neutrons stop working and die?
Cerebral cortex
What are mild AD signs?
Memory loss, confusion, trouble handling money, poor judgement, mood changes, anxiety
What are moderate AD signs?
Increased memory loss, problems recognizing people, troubles with language and thoughts, restlessness, repetitive statements
What occurs in the brain in severe AD cases?
Extreme shrinkage of brain
What are severe AD symptoms?
Weight loss, seizures, skin infections, groaning, increased sleeping, loss of bladder control
Death usually occurs due to what for those with severe AD?
Aspiration pneumonia
Death usually occurs due to what for those with severe AD?
Aspiration pneumonia
What results in cytoskeleton abnormalities?
Dysfunction and death of neutrons
Decrease in synaptic proteins in terminals
Which cells are mostly affected in AD?
Large glutamatergic pyramidal cells in cortex and hippocampus
Cortical interneurons
Cholinergic neurons
What are neurofibrillary tangles?
Fillamentous inclusions in cell bodies and proximal dendrites
Where can neurofibrillary tangles also be found?
Axons and terminals (dystrophic neurites)
Dendrites (neuropil threads)
Tangles are made by….
an isoform of tau clumping together
What is tau?
A stabilizing component of microtubules
How does AD tau differ from normal tau?
Normally soluble, but AD isoform is insoluble
Causes microtubules to collapse
Tau first appears where?
Entorhinal cortex then later in neocortex
What does neurofibrillary tangles disrupt?
Axonal transport
Neurons die but tangles are left behind
What is the precursor protein to amyloid plaque?
Amyloid precursor proteins (APP)
How are senile plaques formed?
- APP sticks through neuron membrane
- Enzymes cut APP into fragments (include beta-amyloid)
- Beta-amyloid fragments come together in clumps (forms plaques)
- Dystrophic axons surround deposits
Which part of the brain does senile plaques effect?
Hippocampus and other areas of cerebral cortex
Which part of the brain does senile plaques effect?
Hippocampus and other areas of cerebral cortex
What is the process for a mature senile plaque to be formed?
- ABeta appears (deposition of amyloid)
- Mature plaque, glial cells, swollen axons (senile plaque formation)
- Fibrillar Abeta surrounded, tangles (mature plaque)
What genetic risk factors are involved in early onset of AD?
- Mutation of APP gene
- Mutation of presenilin 1 gene
- Mutation of presinilin 2 gene
What other genetic risk factors are involved?
Certain alleles for ApoE
Mutation of alpha-2-macroglobulin
A mutation in APP leads to…?
Increased ABeta production
Presenilin 1 and 2 are inherited in what fashion?
Autosomal dominant
Presenilin 1 and 2 promote the formation of what?
Toxic ABeta
What is ApoE? What is its normal function?
Large protein that carries cholesterol in blood
Normally breaks down beta-amyloid
What are the three different alleles known for ApoE? Which is the most common in normal populations? In AD populations?
ApoE3 (most common)
ApoE4 (rare but common in AD)
How might an alpha-2-macroglobulin mutation affect ABeta deposits?
Affects removal
Which two enzymes cleave amyloid precursor protein? What does this produce?
Beta-secretase and presenilin
Produces beta-amyloid
What leads to the formation of plaques?
Beta-amyloid
What is a response to plaques?
Neurofibrillary tangles
