Aging Brain Flashcards
What are the three concurrent processes associated with aging past reproductive age?
`Development
Senescence (decline)
Compensation
What happens during brain development?
the brain increases range and efficiency through differentiation, pruniing and specializaiton
What is associated with senescent processes?
gradually reducing the range and efficiency of the brain function
What is associated with compensation?
De-differentiation where a wider portion of the brain must be recruited to perform the same task and the brain resorts to less efficient pathways
How does the same process that favors differentiation and increased efficiency early on, have adverse affects beyond the age of reproduction?
ex. with the salmon
Cortisol is secreted to help the fish swim upstream to lay eggs, but then later on hypercortisolemia causes atrophy, inability to heal and death
How much volume does a brain lose by 80 years old? Why?
10% partly due to H20 loss, but also:
- loss of synaptic connections
- decreased white matter
- thinning cortex
Which lobes change the least in volume?
parietal and occipital
Which type of matter shrinks more up to age 50?
gray. but then after 50 there is a larger decrease in white matter
Which sexes frontal lobe shrinks more rapidly?
males, which is why older men tend to be socially disinhibited
Which sexes parietal lobe shrinks more rapidly?
Females which is why they tend to get lost while driving
What happens to the ventricles and volume of CSF with age?
the ventricles dilate and there is increased volume of CSF
What does the hippocampus lose with age?
What is maintained?
There is little neuronal loss but there is a loss of volume and synaptic connections
What neuronal systems are most vulnerable to aging?
neocortex and basal forebrain nuclei (septal areas)
Loss of what kind of cell results in decreased learning and memory as we age?
cholingergic (less Ach release)
What does the loss of dopamine causes?
loss of fine motor control
What substance accumulates as the result of cell membrane breakdown?
liposfuschin
What are the subjective memory losses as people age?
What are the objective losses?
Subjective- decreased short term memory and trouble recalling names
Objective- slow motor response, learning, detail recall,
What processes are generally preserved as we age?
- recalling the gist
- social cognition
- general info
- vocabulary
- past events and history
What are motor changes with age?
- decreased strength and muscle mass
- decreased postural stability
- gait disturbance
What are sensory changes with age?
- impaired sight, hearing and smell
2. reduced tactile and vibration sense in lower extremities
What are autonomic changes with age?
- decreased b-adrenergic sensitivity so there is decreased heart rate and stroke volume
- reduced bronchodilation
- reduced awareness of blood sugar drop (more prone to fainting)
- decreased baroreceptor sensitivity- more prone to falls from orthostatic hypotension
What are five major causes for brain function impairment with age?
- apoptosis
- failure of DNA repair
- accumulation of toxic substances like free radicals, damaged mDNA and amyloid
- misfolded proteins
- glycosylation
What can stress induced hypercortisolemia early in life cause?
decreased hippocampal neurons
What does developmental damage do to the percent of DA neurons as a person ages?
people will lose dopaminergic neurons at the same rate, but people with developmental damage will start at a lower set point
What are four ways the effects of aging can be slowed biologically?
- catalases and superoxide dismutases can quell ROS
- misfolded proteins can be refolded or disposed of by Ub system
- hippocampal stem cells can regenerate lost neurons
- shifted pro- and anti-oncogenes
