Chpt 14: Older Adults

Fluid Intelligence (Decline with age)

• Perceptual speed

• Perceptual accuracy

• Working memory

• Inhibitory control

• episodic memory

Crystalized Intelligence (x chg with age)

• knowledge

• verbal comprehension

• emotional processes

• strategies (processing/learning)

• reading/writing

• occupational skills

• autobiographical memory

Age-Related Cognitive changes

• Variability: between indies (> w/ age), w/in indies

• Compensation: use diff strategies

  • Results in only small impacts on activities of daily living

Morphological Changes

• whole brain volume

• Grey matter

• white matter

• Connectivity/volume of: caudete nucleus, PFC, cerebellum, HC

Whole Brain Volume

• Gradula decrease

• Thinning in teen yrs: 20 = 1300g

• Decrease in adulthood: 80 = 1150 g

• 10% loss of brain power (modest)

• Brain is resilient

Grey & White Matter

• Grey matter = cortical thinning w/ age

• White matter = thinning thru/out tracts of brain

• More prominent in males

• Volumes (grey & white) predictcognitive performance

Grey Matter changes

• Fewer dendritic spines

• Fewer dendritic branches

• Fewer capillaries

• Fewer glial cells

White Matter Changes

• less density

• Loss of integrity

• Change in myelination (white matter hyperintensities)

Myelination

• No myelin = slow

• Myelin = faster

• Under myelin the signal loses strength

  • Needs to be renewed at nodes of Ranvier (ion exchg)

• If myelin is too thick → lose strength

White Matter Hyperintensities - Causes

• Occlusion of small blood vessels

• Leakage of plasma fluid

Brain Regions most affected by aging

• Caudete nucleus

• HC: < volume, issues w/ episodic mem

• PFC: < DA, NE, serotonin (chg EF)

• Cerebellum: fine tune motor coordination

Neural Activity

• Reduced activation of the PFC & paraHC gyrus

• Effect size = % signal change

Changes in Lateralization

• Why not all older adults show the same memory declines

• W/ aging lateralization decreases

• Bilateral activation >

• Compensation hypothesis

Lateralization

• Hemispheric asymmetry

• Frontal lobe activation on one side

Blateralization

• Hemispheric symmetry

• Occurs w/ age (< lateralization)

• Compensatory

• Observed w/ WM & visual attention (occipital & PFC)

  • Young had > signal chg in occipital cortex

  • Old > young in PFC

HAROLD

• Hemispheric

• Asymmetry

• Reduction in

• Old

• Adults

Compensatory hypothesis

• Bilateral activation occurs in compensation for age-related effects

• Demonstrated by memory tests & PET data:

  • Young & old-high functioning performed similarly & better than old-low

  • Young had lateralization w/ minimal activation

  • Old-low had lateralization but incrased neural firing (> effort)

  • Old-high had bilateralization w/ less neural fiirng (< effort)

fMRI Measurement

• Measures maemodymic rxn

  • Blood flow

  • Blood oxygenation lvl

  • Blood volume

• Reflects change in microvasculature by measuring O2 lvls

• Active brain areas require O2 to replenish used

Changes in Microvasculature

• Reduction in blood flow w/ aging

• < gas exchg

• Issues w/ nutrient dilvery & waste removal

• Issues w/ cellular comm

Plasticity

Adaptability to change in:

• Response to changing demands

• In response to brain damage

  • Areas take on new tasks (object recognition - temporal/occ)

  • Ex. lose vision; V1 takes on tactile

  • Ex. loss of limb (touch face when phantom pain)

Plasticity - Factors

• Genetics: partially genetically coded

• Lifestyle choices

  • Social interaction (> social interaction, > mem performance)

  • Physical activity (> adaptability to chg, including injury)

Chronic Exercise - BDNF

• Stretching: HC shrinkage

• Aerobic: > BDNF, > HC volume

Chronic Exercise - Dopamine

• > DA lvls

• > grey matter (adult neurogenesis)

• > memory performance

• > D1 receptors in humans & rats

Dopamine: Aging

• Reduction in D1 receptors

  • Measured using PET scan (dopamine binding)

• Reflected in brain activity in rxn to spatial memory task

• < D1 receptor, < spatial memory w/ age

Chronic exercise: HPA axis

• Measured cortisol of Post-menopausal women after interview

• Rumination triggers stress response

• Sedentary-high rumination: strong cortisol/stress rxn & prolonged

• Active:

  • lower stress rxn overall (HPA reactivity)

  • faster recovery from stress-induced cortisol spike

  • Activity counteracts effect of rumination on HPA axis (cortisol)

Neurogenesis - Steps

• Type-1 Stem Cell (Nestlin-GFP): General stem cell w/ ability to differentiate

• Type-2/3 Progenitor Cell (DCX): > differentiation (specifies what it can become)

• Postmitotic immature neuron (Cairetinin): specialized cell

Dentate Gyrus (HC)

• Input from diff modalities

• Form representation (putting voice & face tg)

• Memory that binds info (creating memory by binding info)

Chronic Exercise - Neurogenesis (HC)

• Clear effect for cells that are going to become specialized neurons (DCX, Cairetinin)

  • Maintained > in proliferation 32 days later

  • Stronger effect for new cells/neurons in younger

  • > formation of specialized neurones in older (smaller # new cells )

• > cells in HC (dentate gyrus) → new memories/asso; > cerebral blood flow

• Exercise > in BDNF correlated w/ > HC size

Chronic Exercise - Neurogenesis (Gray/white matter)

• Gray & white matter > in areas involved in inhibition (> frontal lobe connectivity)

  • Interior singulate gyruns, ACC, corpus callosum (connect hemispheres)

• > bilateral activation & connection btwn frontal lobes

  • Compensates for age-related degradation

Synaptogenesis

• Challenging activity (cog engagement) matters more than exercise itself

• > & maintains synapse/neurons in rats

• Applicable for elderly pop

Angiogenesis

• Creation of new blood vessels

• Sprouting (links two capillaries), intussusceptive (branches exisiting capillary)

• Older indies typically have < microvasculature

• Exercise > capillaries (replace lost) → > sites for gas exchange

• Happens in brain regions where vol is reduced w/ age (also > vol)

  • BG, cerebellum, motor cx, HC

Brain Activity

• Small vessels = small signals

• Large vessels = large signal

• Aerobic (walking) = > VO2 max, < brain activation

  • Requires less effort for verb generation after 15 min practice

Brain Activity - Complex

• Lg blood vessels generate > signal than small

• New task generates > signal than a learned task

• Smth done effectively generates < signal than smth that req effort

• Same task can be done w/ diff Strats

Cogntiive performance

• Better inhibition (< interference)

• Faster RT - faster processing speed

• Better memory performance

• Better task switching

• < output over time (< effort)