lecture 2: biological aging

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

• What interventions can facilitate aging from a physical and psychological point of view?

• How do older adults cope with stress?

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.

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

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,...

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…

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?

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.

Changes in Vision

• Cataracts: Opaqueness/clouding of the lens

Without a cataract With a cataract

• Surgery: Replace the lens with an artificial one.

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

Retinal Changes• Macular degeneration

• Diabetic retinopathy

• Decrease in visual acuity

• Functional implications of all these visual changes?

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.

Image courtesy of: http://human-body.net/a_inner.html

Somesthesia

• More pressure to feel on smooth skin.

• Less sensitivity to temperature?

• Changes in pain sensitivity?

• Kinesthesic changes for passive but not active movements.

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?

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?

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.

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?

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

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