·
The "thermostat" within the hypothalamus is less
responsive to changes in both skin temperature and core temperature and
therefore signals shivering to begin at a lower temperature. Shivering in the
elderly does generate normal amounts of heat, but the loss
of subcutaneous tissue with aging results in a loss of insulation,
leading to more rapid loss or gain of heat. Additionally, the basal metabolic rate of the older person is lower,
resulting in less heat to conserve. Finally, some older people may have a
reduced drive to microacclimatize (put on warm clothing) when the surroundings
are cold. All of these small changes (especially in the presence of impaired
cognition or sedative medications) can add up to a
large risk of accidental hypothermia.
·
Blood
flow decreases in both the arterial and portal systems IN LIVER, contributing to increases in the half-life of certain agents and
narrowing the oral dose/parenteral dose discrepancies for drugs that are
heavily metabolized during the "first pass" through the liver
·
Phase
I reactions, oxidations and reductions, decrease
·
Phase
II reactions, acetylations and glucuronidations,
are generally unchanged
·
There
is no age-associated decrease in hemoglobin in healthy men and women.
·
Older persons spend more time in stage I (light sleep/sleep-awake
transition) and less time in stage IV sleep.
·
The Diogenes
syndrome is a condition of self-neglect, independent of depression
and cognitive impairment, that may represent the evolution of a personality
disorder. Individuals are unkempt and may often exhibit hoarding behavior. As
they retreat socially, their behavior may preclude proper nutrition so that
malnutrition is common. The 1-year mortality rate
may be as high as 50%.
·
Diastolic
dysfunction results from impaired relaxation in heart failure with preserved ejection fracture
and may account for half of all cases of heart failure in people over 80.
Clinically, the symptoms may be similar to those of systolic dysfunction, but
the traditional therapy for systolic dysfunction can actually worsen
ventricular filling and increase the risk of orthostasis and syncope. Treatment for diastolic dysfunction may include calcium
channel blockers or beta blockers.
·
An S4
likely results from the decreased compliance of the ventricular septum and is
very common in older persons and usually of limited clinical significance. The
presence of an S3 gallop, however, is
never normal in an older person and is characteristic of CHF.
·
Aortic
sclerosis is the source of many benign murmurs in
the elderly, resulting from hardening and fibrosis of the aortic cusps, and is
not hemodynamically significant.
·
A fifth agent, memantine, targets acetylbuterase
and also appears to slow the progression of the AD.
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