Today Neuroimaging Dementia in aging—get some charts from her lecture Ocular changes with aging—learn hyperopia

Working Memory is the ability to maintain and manipulate information over short periods of time necessary to guide behavior

Mean Reaction Time (msec) Task Condition 70s-80s 50s-60s 20s-30s ALONECOUNTINGDIGIT SPAN

Structural brain changes with aging changes in brain volume youngold

STRUCTURALFUNCTIONAL Magnetic Resonance ImagingPositron Emission Tomography

OLD YOUNG

ELDERLY UNDER RECRUITMENT OVER RECRUITMENT YOUNG OLD NON-SELECTIVE RECRUITMENT

Memory Load Young Old Reaction Time (msec)

FASTESTSLOWEST YOUNG OLD

Summary Age-related decline in selective cognitive processes Functional MRI is a powerful method with excellent spatial and temporal resolution to study the physiological basis of cognitive decline in normal aging Evidence for selective prefrontal cortical dysfunction (I.e. under-recruitment) with normal aging Possible neural as well as behavioral compensation

Questions What is fMRI? What is it used for and how does it work? What area of the brain has been shown to have change in older people?

AGING OF THE NERVOUS SYSTEM—FUNCTIONAL CHANGES Again, in the normal aging brain the changes are relatively few. However impaired function and increased pathology do occur. Major functional deficits/ pathologies involve: Motility (e.g. Parkinson’s Disease) Senses and communication Cognition (e.g. dementias) Affect and mood (e.g. depression) Blood circulation (stroke, multi-infarct dementia) Parkinson’s Disease: Chapter 8, pp Dementias: Chapter 8, pp

Dementia Dementia: global deterioration of intellectual and cognitive function characterized by 5 major mental functions: –Orientation –Memory –Intellect –Judgment –affect –(But clear consciousness)

Dementia (cont.) There are two types of dementia: –Reversible –Irreversible

Amyloid Connections In Alzheimer’s, amyloids are made and accumulate in brain tissues and cause disturbances. Maybe these could be a point of intervention to prevent progression of alzheimers.

Characteristics of Multi Infarct Dementia (table 8.9) Transient ischemic attack or stroke Hypertension, arrythmia Focal neurological signs Stepwise deterioration

Questions What are the causes of reversible dementia? What are the characteristics of multi-infarct dementia? What are the major functional deficits/pathologies in aging?

Aging of the Visual System

Definitions To look at a near source, the lens has to accommodate (become more round); to look at a far source it doesn’t have to accommodate. Myopia: nearsightedness because eyeball is too long or lens is too strong. Corrected with concave lens. Hyperopia: farsightedness due to eye too short or lens is not strong enough. Corrected with convex lens Presbyopia: loss of focusing power of lens because it has stiffened—results in difficulty seeing objects close up which necessitates lens to accommodate.

Aging of the Visual System Structural Changes (See handout given in class) –Tear Film: Dry eyes or tearing –Sclera: Fat deposits – yellowing Thinning – blueing –Cornea Diameter does not change after age 1 Shape changes –Retina Photoreceptor density decreases; other layers become disordered (rod density decreases with age, cone density remains) Illuminance decreases with age –Lens Increased size and thickness Becomes more yellow

Aging of the Visual System Function –Corneal and Lens Decreased accommodation power (loss of presbyopia: loss of focusing power of lens because it has stiffened—results in difficulty seeing objects close up.) Increased accommodation reflex latency Refractive error becomes more hyperopic with age Corneal sensitivity decreases Scatter increases –Pupil Size decreases with age, particularly for dim light conditions.

Aging of the Visual System –Retinal (MANY changes due to decreased amt of light reaching retina) Decreased critical flicker frequency Visual acuity declines Visual Field decreases Color vision changes Darkness adaptation is slowed Increased glare problems, longer time to recover from glare Decreased light reaches retina Visual acuity declines most with age when tested in low contrast with dim light. The difference as compared to young people is very significant in this case. (not as significant if tested with high contrast, bright light) Attentional visual field size decrease Stereopsis (close-up depth perception) shows large loss with age due to difference in function of 2 eyes. Face recognition impaired

Other changes Words per minute decrease in reading Increased hyperopia: (farsightedness because eye is short) Increased astigmatism (cornea of eye is asymmetrically curved causing out of focus vision)

Graph from handout—summary of some main points Most change with age in: – acuity in glare 18x worse with aging –Next: glare recovery 15x –Next: attentional field 12x –Etc…

Aging of the Visual System Recommendation to Accommodate Problems: (she didn’t discuss in too much detail, but good to know) –Wear appropriate optical correction –Increase ambient light –Make lighting even and reduce glare –Improve contrast in critical areas –Avoid rapid changes in light level –Avoid Pastel –Allow more time