Cognitive reserve and cognitive abilities

Proposal details

Title: Does cognitive reserve differentially affect specific general cognitive and social cognitive abilities in aging and dementia?
Research Area(s): Thinking and Cognition
Development and Aging
Background: Cognitive reserve attempts to account for the ability of some individuals to attenuate clinical manifestation of age- and neurodegenerative-related brain changes and pathology. Engaging in a cognitively stimulating lifestyle via exposures such as educational attainment, occupational complexity, and engagement in leisure activities is thought to increase cognitive reserve; this allows individuals, through unknown mechanisms, to actively adapt to accumulating neuropathology and retain cognitive functioning. Those with high levels of cognitive reserve display better general cognitive performance and are able to maintain cognitive functioning for longer, offsetting development of cognitive impairment and dementia. High levels of cognitive reserve can even preserve cognitive function to a degree once clinical dementia has manifested. However, the differential influence of cognitive reserve on an extensive range of cognitive domains has not been thoroughly investigated. Research has tended to examine the influence of cognitive reserve on global measures of function or ability. Although some results have been reported for specific cognitive domains, such as types of memory, processing speed, attention, and executive function, this has received less focus; it is still unclear as to which specific cognitive domains are related, or unrelated, to cognitive reserve. Furthermore, social cognition (which involves comprehending and responding to social situations and stimuli) declines with age and has been linked with age-related declines in general cognitive ability. However, little is known about how cognitive reserve affects social cognition. Examining the relationship (or lack of relationship) between cognitive reserve and specific general cognitive abilities and social cognitive abilities will enhance understanding of how cognitive reserve affects individual cognitive domains. Identifying domains which are related to cognitive reserve could lead to development of intervention strategies targeting these cognitive abilities. Conversely, if unrelated, specific domains may therefore be considered reserve-free measures, immune to compensatory mechanisms employed by those with high cognitive reserve. Tests unaffected by cognitive reserve hence may afford a better indication of underlying age- or neurodegenerative-related brain changes. In addition, individual alpha frequency (IAF) and peak alpha frequency (PAF) have been associated with a number of cognitive abilities including reasoning, memory and processing speed. Differences have also been found between those with Alzheimer’s disease and healthy controls. Recent evidence has suggested that when individuals have greater levels of task-related attention at rest (indexed by higher IAF), less resources are subsequently required to perform the task (Jann et al., 2010). However, it is unknown whether IAF/PAF differs between people with high and low levels of cognitive reserve. If associations between cognitive reserve and IAF are found, this will shed further light on the underlying mechanisms of cognitive reserve.
Aims: This study will aim to examine how cognitive reserve relates to domains of general cognitive ability and social cognition, as well as electroencephalographic measures of brain activity. Specific aims include: 1) to determine whether cognitive reserve is associated with individual general and social cognitive domains in healthy older adults, those with mild cognitive impairment (MCI), and those with Alzheimer’s disease (AD); 2) to compare how cognitive relates to specific general and social cognitive domains across participant groups (healthy controls, MCI, and AD) to determine; 3) to examine relationships between general cognitive domains and social cognitive domains and determine whether potential combined factors do or do not relate to cognitive reserve; 4) to determine whether cognitive reserve is associated with IAF/PAF in healthy adults aged 60 and older; and 5) investigate whether CR affects the relationship between IAF/PAF and cognitive status (i.e., healthy, mild cognitive impairment, or Alzheimer’s disease).
Method: IntegNeuro thinking and emotion data will be selected for healthy controls, mild cognitive impairment (MCI) and Alzheimer’s disease (AD) cases aged 60 years and older, with relevant demographics and clinical data (medical history and psychological measures), from the Brain Resource International Database. From this data, a cognitive reserve proxy will be computed (using educational and occupational data) and used in statistical analyses to examine whether level of cognitive reserve is related to performance on any of the cognitive and emotional/social cognition tests. In addition, electroencephalogram (EEG) alpha frequency data will be requested for healthy controls, MCI and AD cases aged 60 years and older. Correlational and regression analyses will be used to investigate the main aims. Independent analyses for all three participant groups will be run in order to identify whether cognitive reserve operates differently for healthy controls, those with MCI, or those with AD.