Lecture 7: Ageing and Physiology Flashcards
How does sensory/perceptual/motor ability change with age?
Sensorimotor and cognitive declines more strongly overlap with increasing age, but there are both common and independent factors driving declines in sensorimotor and cognitive abilities.
How do sleep and circadian arousal change with age?
SWS is important for episodic memory but is particularly less efficient in older age; circadian arousal may also impact cognitive abilities
How does physical exercise impact the psychology of ageing?
Physical exercise interventions generally improve cognitive abilities, brain plasticity, and mental and physical health across the lifespan
Sensory, Perceptual & Motor Abilities
Taken from the US Center for Disease Control and Prevention (CDC)- Why do we see a decline in sensory abilities?
- Loss in sensory abilities like vision, hearing (and even others like the sense of smell, taste, etc.) sharply decline with age
- This is US data but it’s quite standard across industrialized countries
This lead researchers like Paul Baltes and Ulman Lindenberger to ask: does this sensory decline have anything to do with the cognitive decline we see?
- This is US data but it’s quite standard across industrialized countries
Sensory, Perceptual, & Motor Abilities (Schneider & Pichora-Fuller, 2000; Anstey & Smith, 1999; Krall et al., 2014, etc.)- description
- Sensory variables can include not just vision and hearing, but other factors like balance, walking and gait, grip strength, and proprioception (the feeling of your own body in space, or your sense of self-movement and body position)
- These and many more variables tend to correlate with each other so strongly in older age that, statistically, they represent a “common factor” of sensory, perceptual, and motor ability
- That is, there is a “latent” (unobserved) variable that reflects shared variance of these different physiological functions
Many of these cross-sectional studies have reported moderate to large inter-associations between this common factor and age
What is the common cause hypothesis?
- Age-related decline in cognitive and sensorimotor function is due to deterioration of common neurological processes
- Sensorimotor ability indicates the biological integrity of the brain; thus it’s a strong predictor of cognitive decline
-Because fluctuation of sensorimotor abilities increases with age, this neurological deterioration and its correlation with cognitive ability increases with age
Who showed evidence for “controlling for sensorimotor functioning (vision, hearing, balance/gait) reduces the age-intelligence relation to null” ?
- Lindenberger and Baltes showed evidence for this in a large sample of 516 older adults (70-103) from the Berlin Aging Study (BASE)
- They derived a second-order factor of “intelligence” that comprised the other factors of reasoning, knowledge, etc.
- Sensorimotor function factor was a composite of vision, hearing, and balance/gait
The sensorimotor factor largely mediated the effects of age on intelligence.
What are the implications of the common cause hypothesis?
- Sensory function plays a causal role in cognitive tasks, and thus what is often attributed to age differences in cognition may be wrong, and it’s instead sensory factors
What is the effect of sensory deprivation?
Sensory, perceptual and motor ability—> social engagement—> cognitive ability
Sensory deprivation= Negative effects of sensorimotor ability on cognitive ability indirect via increased social disengagement
Sensory deprivation= declining sensory acuity creates communication and mobility difficulties, increasing the likelihood of social withdrawal and disengagement from intellectually stimulating activities which could have knock-on effects on cognitive ability over an extended period (years to decades)
What is the cognitive load on memory performance?
Sensory, perceptual and motor ability—> Cognitive ability
The causal direction could work in reverse – deficits in cognitive ability may adversely affect sensorimotor function
Cognitive load on sensory performance – for example, deficits in sustained attention may diminish an individual’s capacity to detect auditory or visual stimuli
What are the direct effects on age on sensorimotor and cognitive variables?
research showed both indirect age effects, as the common cause hypothesis predicts, as well as direct effects of age on sensorimotor and cognitive variables
In other words, age-related declines in cognitive and sensorimotor functioning can be attributed to both a broad common cause factor and separate domain-specific mechanisms
- Longitudinal studies show more modest associations between sensorimotor and cognitive declines.
- This provides further support for the role of domain-specific factors (Lindenberger & Ghisletta, 2009)
Ohayon et al., 2004 Sleep- results
sleep declines with age
slow wave sleep (SWS) is particularly diminished as age increases
- Proportion of the sleep duration that each age spends in that respective sleep stage - WASO = wake after sleep onset - Older adults sleep less and awaken more frequently during the night - Diminished slow-wave sleep (SWS) -- decreases in slow-wave activity (SWA), especially over the PFC - Decreases in spindle density Time in REM sleep remains unchanged, but there is a decrease in phasic REM in OAs
Rasch et al., 2007 Science- introducing odours to sleep
- participants played the equivalent of the “memory” game before sleep
- They were presented with an odour (roses) during learning (exp 1, 3, 4)
- memory improved when re-presenting the odour during SWS vs control (Exp. 1)- no differences in the other experiments that did NOT present the odour during learning and short wave sleep
Sleep and Circadian Arousal (Harand, Bertran, Doidy et al., 2012 Frontiers in Neurology)- A framework for how aging affects sleep-dependent memory consolidation
During wakefulness- information is encoded in neocortical and hippocampal networks
During SWS- repeated activation of recently learned information within hippocampal networks
Reactivations stimulate the transfer of memory traces towards neocortical states for long-term storage
Reactivations are associated with sharp waves-ripples and are driven by slow oscillations that synchronize hippocampal memory reactivations with the occurrence of sleep spindles.
Why do older people have impaired memory? (hippocampus + cortisol receptors)
- With increased age, there are several things that impact this hippocampo-neocortical dialogue, one of which is reduced SWS
- There are also changes in the hypothalamo-pituitary-adrenal axis leads to increases in evening cortisol levels with age, but memory consolidation requires low cortisol levels during sleep.
- Hippocampus contains a high density of cortisol receptors, and thus the increased cortisol levels could impair the hippocampus’s function to transfer memories for long-term storage in the neocortex.
