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Cognitive interventions (methodological limitations/disadvantages of…
Cognitive interventions
major modifiable risk factors for dementia; PREVENTION
depression, midlife hypertension, physical inactivity, diabetes, midlife obesity, hyperlipidemia, smoking
more research is needed for coronary heart disease, kidney dysfunction, diet, cognitive activity
all account for ca.50% of all AD cases
methodological limitations/disadvantages of cognitive interventions
many risk factors are interrelated eg. diabetes & obesity: not possible to state that reduction of a certain risk factor could lead to a lower disease incidence because of that specific factor
limited cross-validation
evidence reflects Western population
various measures used to define cognitive change eg. MMSE score of 23 or less, 3 points change in MMSE, incident MCI -> difficult to make direct comparisons
often predominant focus on observational studies (excluding randomized control trials) -> valuable information lost, causality between predictors & outcome can't be directly demonstrated
quality of studies on which the interventions are based is questionable eg. due to publication bias
exposure & outcome misclassification, confounding, still no core set of outcome measures to compare the effectiveness of different cognitive programs
using indirect markers associated with aging
questionable whether the effects of cognitive interventions generalize to improvement in everyday life activities
effect sizes larger when outcome measures were directly related to type of training but not generalized to overall cognitive functioning
too few show improvements in more than one specific cognitive domain
most intervention studies used memory performance as the primary outcome measure but only few studies used similar tests to measure memory functioning
executive function was the 2nd mostly included outcome measure but almost no intervention programs aimed directly at improving EF
there is little evidence that training effect can persist beyond few months after the intervention
How could mind-body practice affect the most common mechanisms of aging?
Macroscopic brain anatomy:
progressive decline in brain volume, demyelination, dendritic shrinkage
--> less pronounced negative correlations between age & cerebral measures in meditators ie. GM, WM volumes, WM integrity
--> younger brains, short-term tissue gain
Inflammation:
changes in cell signaling: endocrine, neuroendocrine, neuronal communication
weakened immune response
can be fueled by increased ROS -> "inflammaging"
--> reduced pro-inflammatory state in meditators
Telomeres:
leads to altered gene transcription, altered cell functioning, mitochondrial dysfunction, apoptosis, increases ROS production via altered signaling
can be rehired by enzyme telomerase
DNA damage in this region isn't well repaired and accumulates over time
--> meditation can increase telomerase activity &telomere length -> less inflammatory signaling, less stress, more functionally intact cells
to better maintain brain tissue, preserve cognitive & emotional reserves, diminish dementia risk
What cognitive INTERVENTIONS do we have? What can be done?
more childhood education, exercise, maintaining social engagement, reducing smoking, and management of hearing loss, depression, diabetes, and obesity
cholinesterase inhibitors at all stages, or memantine for severe dementia (cholinesterase not effective in MCI)
tailored to unique individual and cultural needs, preferences, and priorities and incorporate support for family carers
STrAtegies for RelaTives (START) or Resources for Enhancing Alzheimer’s Caregiver Health intervention (REACH) --> reduce depression risk of family carers
protection from possible risks of the condition: self-neglect, vulnerability, managing money, driving, using weapons
Management of the neuropsychiatric symptoms of dementia eg. agitation, low mood, or psychosis
Technological interventions have the potential to improve care delivery but should not replace social contact
What is the role of stress in the aging process?
high basal levels of glucocorticoids, if sustained over time, lead to increased ROS production & increased risk of DNA & cellular damage
high CRH levels stimulate the production of pro-inflammatory cytokines
reduced neuroplasticity & neurogenesis, even reduced volumes of hippocampus
Stress regulation through mind-body practice: meditation fosters adaptive emotion regulation & emotional wellbeing, reduces cortisol levels, reduces rumination (also observed in longitudinal studies)