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

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ALONE COUNTING DIGIT SPAN

Structural brain changes with agingchanges in brain volume

young old

STRUCTURAL FUNCTIONAL

Magnetic Resonance ImagingPositron Emission Tomography

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Memory Load2 6 2 6

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Summary

• Age-related decline in selective cognitive processes

• Functional MRI is a powerful method with excellent spatialand temporal resolution to study the physiological basis ofcognitive 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. 110-113Dementias: Chapter 8, pp. 130-136

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

TABLE 8-7 Underlying and Reversible Causes of Dementia

D Drugs E Emotional disorders M Metabolic or endocrine disorders E Eye and ear dysfunctions N Nutritional deficiencies T Tumor and trauma I Infections A Arteriosclerotic complications

i.e., myocardial infarction, stroke or heart failure

Table 8-10 Selected Characteristics of Alzheimer’s Dementia

Anatomo-Histology Pathology Metabolism

Brain atrophy, flattening of gyri, widening of sulci,

& cerebral ventricles

Loss of cholinergic neurons, in nucleus of Meynert,

hippocampus & association cortices

Loss of adrenergic neurons,

in locus ceruleus

Denudation of neurons, stripping of dendrites,

damage to axons

Increased microglia

Accumulation of cell

inclusions: lipofuscin, Hirano and Lewy bodies,

altered cytoskeletal Tau proteins,

ubiquitin

Neurofibrillary tangles, neuritic plaques with

amyloid,

Perivascular amyloid, distributed throughout the

brain, but especially in frontal, prefrontal lobes,

Hippocampus, association cortices

Decreased oxidative

metabolism, slower enzyme activity (Ch. 7)

Free-radical

accumulation (Ch. 5)

Impaired iron homeostasis (Ch. 7) Other minerals, zinc,

aluminum

Reduced level/ metabolism/ activity of

neurotransmitters

Increased amyloid peptide with accumulation of

amyloid proteins

Increased prion protein

Altered immune response

TABLE 8-9 Characteristics of Multi-Infarct Dementia

History of abrupt onset or stepwise deterioration History of transient ischemic attack or stroke Presence of hypertension or arrhythmia Presence of any neurologic focal symptoms or signs

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