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Neurocognitive and Language Function in Aging and Dementia Vanessa Taler, Ph.D. University of Ottawa Élisabeth Bruyère Research Institute
The aging brain
• lower volumes of grey matter resulting from reduced synaptic densities • some regions are more affected than others • e.g., prefrontal cortex • medial temporal structures
images from http://www.cse.buffalo.edu/, http://www.mybrainnotes.com/
Changes in white matter
Effects of aging on cognitive function
• With normal aging, we see declines in: • processing speed • episodic memory • working memory • executive function
• these declines are associated with brain changes (e.g., prefrontal volume, white matter integrity)
Intelligence
• Fluid intelligence: ability to think and reason abstractly and solve problems • Correlated with volume of prefrontal cortex
� Crystallized intelligence: the ability to use skills, knowledge, and experience
� Preserved in normal aging
Language changes with age
• Language function remains largely intact • However, it can be afffected by other changes with age (e.g., in processing speed, working memory) • Discourse comprehension is affected by both processing deficits and increases in language experience related to age: • working memory (integration of concepts, maintenance of thematic information over multiple sentences). • topdown influences (real world knowledge)
Considerations
• Many common health problems can have a deleterious—and additive—effect on cognition • Medications can affect cognitive function • Sensory acuity (visual and hearing function) is an important predictor of cognitive performance • Cross-‐sectional vs. longitudinal studies give different results
What is dementia?
• Significant loss of intellectual abilities such as memory capacity, severe enough to interfere with social or occupational functioning. • Criteria for the diagnosis of dementia include: • impairment of attention, orientation, memory, judgment, language, motor and spatial skills, and function • by definition, dementia is not due to major depression or schizophrenia.
What causes dementia?
• Most common causes include: • Alzheimer’s disease (AD) – 64% of cases
• vascular dementia (VaD) – up to 20% of cases
• Lewy body dementia (LBD) – 5-‐15% of cases
• frontotemporal dementia (FTD) – 2-‐5% of cases
• atrophy • senile plaques: buildup of beta-‐amyloid may interfere with neuronal communication. • neurofibrillary tangles: threads of tau protein become twisted.
image from http://alzheimer.ca/
Memory in AD • Memory impairment + impairment in one other cognitive domain • Affects primarily declarative memory (not procedural) • Declarative memory = memory for what • semantic memory (world knowledge, knowledge about the meaning of things) • episodic memory (personal memories)
• Procedural memory = memory for how (e.g., how to ride a bike) • Often remote memories are better recalled
Other cognitive domains in AD
• Impairments are also seen in: • executive function • judgment, decision making • calculations • visuoperceptual function • language function
Other dementias
• Lewy body dementia: • both AD-‐like and Parkinsonian symptoms (rigidity; tremors; stooped posture; slow, shuffling movements.); visual hallucinations
• Vascular dementia: • often co-‐occurs with AD and manifests similarly • stroke is a common cause; symptoms vary depending on brain regions affected
• Frontotemporal dementia: • behavioural variant (frontal) • language variant (temporal)
Language deficits in AD
• Word-‐finding difficulty • Gradual loss of knowledge about word meaning • Deficits in standardized language tests: • Naming • Verbal fluency, especially semantic fluency
• Language production • semantically impoverished discourse that is lacking in coherence
Communication in dementia
• Communication is profoundly affected in dementia, and has a major impact on quality of life
• Declining communication function leads to: • increased stress
• loneliness, and social withdrawal
• earlier institutionalization
How do we improve communication?
• Learning about dementia, its progression, and how it affects individuals. • Believing that communication is possible. • Focusing on remaining abilities and skills. • Reassuring the individual with dementia and being positive. • Meeting people with dementia where they are and accepting their reality.
(Alzheimer Society of Canada)
Strategies for communication cont.
• Eliminate distractions (TV, radio, etc.)
• Use body language and non-‐verbal communication
• Letting the person see your face helps them understand you
• One thing at a time
• Don’t use elderspeak!
The effects of bilingualism
• The number of bilinguals in Canada is large and increasing • Bilingualism affects neuropsychological assessment, especially since most tasks are administered verbally. • Bilingual patients prefer care in the native language, and caregiving in the second language reduces apparent competence and quality of life.
• Bilingualism may delay the onset of dementia. • Why?...
What is “cognitive reserve”?
• Cognitive reserve (CR) is the brain's capacity to cope with cerebral damage to minimize clinical manifestations. • Researchers do not yet fully understand what CR is but some factors may include: • education • occupation • social interactions • physical activity
• “Use it or lose it” – bilingualism may be a form of “using it”
Looking after your brain
• Stay intellectually engaged • At best, mental activity seems to protect against age-‐related declines and progression to AD. • At worst, it increases an individual’s baseline level so that age-‐related declines begin to affect everyday functioning later in life. • Enriched environments stimulate neurogenesis in aged rats, indicating a possible mechanism for the benefits of cognitive stimulation.
Looking after your brain cont.
• Maintain cardiovascular physical activity
• Exercise appears to:
• aid executive function
• reduce declines in tissue density in frontal, parietal and temporal cortex
Looking after your brain cont.
• Minimize chronic stressors • Proneness to distress is associated with increased risk of AD and a faster rate of cognitive decline • Increased glucocorticoid levels, which accompany stress, might damage hippocampal neurons over the lifespan
Thanks to:
• Alzheimer Society of Canada
• Canadian Institutes of Health Research
• Élisabeth Bruyère Research Institute
• All the members of my lab!