Normal Aging Flashcards
Identify problems with the connotation of “normal aging”
when things that are “common” considered “normal”, they are traditionally no longer treated. The example was memory loss- there should not be memory loss with age and if there is, it can not be considered normal. The analogy is blood pressure. It should not just rise because it is possible to keep it down and even lowering a portion of what it is can do a great deal to prevent stroke, heart atack etc
Describe methodological challenges in studying aging physiology, particularly as applied to the nervous system: Longitudinal studies:
What are cohort effects?
are rare
Dropouts — why did they drop out?
How do we separate (subclinical) disease from aging changes?
Heterogeneity — generalizations more difficult; if something happens to an entire generation, does that mean that that’s an effect of age, or just of that generation (great depression, war, etc)
Give examples of physiologic heterogeneity as it relates to changes in the nervous system in older adults
excess capacity in organs and biological systems; we’re given this reserve at birth, and it tends to decrease over time.
The degree to which this is true is HETEROGENEOUS – note the clustering at 40 c/w the spread at 100
even when most of the excess capacity is gone, we may experience little or no decline in function.
A secret of successful aging is to slow down the loss of physiologic reserve.
Describe changes in physiology and anatomy affecting the nervous system with age
Significant molecular, structural, cytoskeletal, neurochemical and vascular changes in the brain.
Structural changes are diffuse – affect cerebellum as well as cerebrum
Gray matter = linear decline; white matter = nonlinear decline.
Increase in atherosclerosis and arteriosclerosisRecall physiologic reserve
motor changes:
Possible contribution of motor unit “dropout” to age-related sarcopenia Decreased strength Decreased speed of gait Stretch reflexes less sensitive Ankle reflexes may be decreased Decreased “righting” reflexes
while bp has been shown to increase almost universally as people age, this can not be thoguht of as normal because:
even lowering bp by a fraction can prevent stroke and other major disabiling events
Disease is common but
disease is never normal.
Use of normal implies not beneficial to treat
Stenosis refers to the narrowing of a structure. In this case, it is used to signify an encroachment on function, illustrated above by the progressively smaller area under the “physiologic limit” curve, with increasing age. When the body is subjected to stress, it uses _______ to ______. The _______. With age, the physiologic reserves of each organ system diminish. As a result, an insult, easily buffered by the young organ, may push the older organ’s ability to maintain homeostasis beyond the “physiologic limit,” leading to an acute injury or disease state.
An example is the aging heart. Exercise increases the oxygen demand of the body. Functional reserve allows the heart to respond by increasing cardiac output (CO) accordingly. In the older heart, loss of cardiac functional reserve limits the extent to which the heart can augment CO in response to exertion. This can predispose the heart and other organ systems to disease as a result of an inadequate blood supply.
Note the decline in physiologic reserve on the right side of the picture. This illustrates the drop-off in reserves that occur in the very end stages of life.
This is one explanation for why it is common for very elderly individuals to be “frail”, susceptible to more disease and injury, and less able to recover from such states.
physiologic reserves, maintain homeostasis, greater the stress, the more physiologic reserves are engaged.
Structural changes are diffuse – affect:
cerebellum as well as cerebrum
Gray matter displays a=______; white matter = _______.
linear, nonlinear; Increase in atherosclerosis and arteriosclerosisRecall physiologic reserve
what is responsible for volume loss?
Nerve cell death; dendritic retraction and expansion; synaptic loss and remodeling; glial cell reactivity
the two pathological factors that may be involved in degeneration at the molecular level of the cytoskeleton:
amyloid plaques, and tau/alpha-synuclein proteins: insoluble depositions in the extra cellular space
the presence of amyloid plaques, and tau/alpha-synuclein proteins:
IS PRESENT IN NORMALLY AGING ADULTS AND DOES NOT CERTIFY THAT THE PERSON HAS AD
TESET: amyloid plaques, and tau/alpha-synuclein protein deposits are _______ while the difference is that the plaques and tangles are ______ in AD as compared to normally aging adults
present in both normally aging adults and patients with AD; more focused in the medial-temporal region as opposed to normally aging adults (all dependent on location and amount of accumulation)
some of the pathologic neuronal changes include:
Dendrites regress and there is loss of dendritic branches and spines – affects neuroplasticity and ability to handle insults (reduces physiologic reserve); results in a loss of synapses; also may reflect failure of cells to eliminate products of peroxidation-induced cell damage
