lecture 2: biological aging
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Lecture 2: Biological Aging. September 19, 2007. Outline for Today. How do various systems change with age? Video: Stealing Time: The New Science of Aging- Episode 2: Turning Back The Clock Audiovisual Library; Call number 005992 - PowerPoint PPT PresentationTRANSCRIPT
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Lecture 2: Biological Aging
September 19, 2007
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Outline for Today
• How do various systems change with age?• Video: Stealing Time: The New Science of
Aging- Episode 2: Turning Back The Clock Audiovisual Library; Call number 005992
• What interventions can facilitate aging from a physical and psychological point of view?
• How do older adults cope with stress?
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How Long Will I Live?
• Try to play the longevity game: http://www.nmfn.com/tn/learnctr--lifeevents--longevity.
• Ask questions about your family history and lifestyle factors.
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Longevity
• Average Life Expectancy: Age at which a particular cohort can expect to live
• Maximum longevity: Oldest age a member of a species can live.
• Active vs. Dependent Life Expectancy
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Ethnic and Gender Differences
• In Canada, individuals of ethnic minorities often live longer: Selection during the immigration process?
• Gender differences in longevity: Women less susceptible to genetic disorders, lower metabolic rate, lower testosterone,...
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What Is It Like To Age?
• Let’s imagine what those physical changes we will discuss today might feel like.
• While you listen to the lecture, please keep a few things in mind…
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Questions To Keep In Mind
• What do you think would happen out in the real world with those limitations?
• What obstacles do you think you would come across?
• How do you think other people would respond to you? Would you feel different about yourself?
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Structural Changes in the Eye• Reduction in pupil size and ability to dilate
the pupil.
• Loss of accommodation: Leading to presbyopia.
• Decrease in the amount of light passing through the lens: Need for increased lighting.
• Increased sensitivity to glare.
• Longer time for light/dark adaptation.
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Changes in Vision
• Cataracts: Opaqueness/clouding of the lens
Without a cataract With a cataract
• Surgery: Replace the lens with an artificial one.
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Changes in Vision
• Glaucoma: Elevated pressure in the eye due to a build up of aqueous fluid.
• Risk factors:– Age– Race – Cardiovascular
disease– Diabetes
Image courtesy of National Glaucoma Research
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Retinal Changes• Macular degeneration
• Diabetic retinopathy
• Decrease in visual acuity
• Functional implications of all these visual changes?
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How Is Hearing Affected by Aging?• Presbycusis: Reduced ability to hear high-
pitched tones.• Loss tends to be more pronounced in
men.• Four types of changes in the ear:
1) Sensory changes due to atrophy and degeneration of receptor cells.
2) Neural changes due to loss of neurons in the auditory pathways of the brain.
3) Metabolic changes.4) Mechanical changes.
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Image courtesy of: http://human-body.net/a_inner.html
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Somesthesia
• More pressure to feel on smooth skin.
• Less sensitivity to temperature?
• Changes in pain sensitivity?
• Kinesthesic changes for passive but not active movements.
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Balance & Fall Prevention• The leading cause of injury for those over
age 65 (OMA, 1992)
• 40% of falls result in hip fracture.
• In Ontario, 600 people over the age of 65 died yearly between 1985-1990 as a direct or indirect consequence of falling.
• Why are older adults at higher risk for falls?
• What are the consequences?
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Taste and Smell
• Gradual decrease in taste ability.• Smell: Decline after 60 years old but great
interindividual differences.• Consistently seen in Alzheimer’s disease: Due to
changes in temporal lobes.• Studies of tau protein in mice also provide a link
to AD and smell dysfunction (Doty et al., 2004)• What could be the functional impact to such
changes in taste and smell?
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Psychological Implications
• Social isolation, especially when mobility is an issue → Depression.
• Prevent from engaging in healthy behaviour like exercising or cooking for oneself.
• Prevent from engaging in pleasurable leasure activity. e.g. Can’t read because of cataracts.
• Become dependent upon a caregiver, while often offering benefits for both parties, can cause additional tensions.
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Cardiovascular Changes in Aging
• Stiffening of heart muscles and arteries.
• Decrease in heart beat at rest and volume of blood pumped.
• Cardiovascular disease: The most prevalent cause of death in Canada.
• Can you name some genetic/physiological factors and lifestyle factors that increase risk for cardiovascular disease?
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Health Canada. (2002). Canada’s aging population. Ottawa, ON: Minister of Public Works and Government Services. Retrieved from http://www.hc-sc.gc.ca/seniors-aines/pubs/fed_paper/pdfs/fedpager_e.pdf
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Cerebrovascular Accident or Stroke
Images courtesy of: http://www.med.harvard.edu/AANLIB/home.html
Fatal right-sided stroke Left-sided stroke causing speech arrest