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Attention and memory components in every-day cognitive problems in aging

Periodic Reporting for period 1 - MEMORAGE (Attention and memory components in every-day cognitive problems in aging)

Reporting period: 2017-03-01 to 2018-08-31

Many older individuals experience age-related cognitive decline in their every-day tasks. Cognitive frailty affects elderly’s independence, quality of life, and need for care. Understanding and counteracting cognitive difficulties in older age is therefore of both societal and economical interest. While basic research has revealed essential knowledge on age-related cognitive and neuronal changes, the correlation between laboratory task performance, brain alterations, and experienced difficulties in daily life is imperfect. Presumably, laboratory tasks, while optimized to isolate cognitive processing components, are too simplified to depict the complexity of cognitive facets we find real-world tasks. The aim of this project is to achieve a better mechanistic understanding of age-related cognitive changes using novel search tasks, which are experimentally well-controlled on the one hand and share important features with real-world tasks on the other. These search tasks permit quantifying cognitive abilities in older age with higher ecological validity. By combining the behavioral search tasks with measures of brain activity, we further identify the neural underpinnings of functional preservation and decline. Our results will be integrated in and extend the current neuro-cognitive aging theories and advance the development of neuropsychological assessment procedures.
In the first period of this project at the Visual Attention Lab, Brigham & Women’s Hospital, Harvard University, under supervision of Prof. Jeremy Wolfe, we developed “extended” hybrid (visual and memory) search and foraging tasks to measure cognitive performance in healthy older adults. In visual search tasks, observers look for a target item among distractor items. For example, where is the coffee maker in the kitchen? In hybrid search, observers search for any of several targets. For example, look for coffee makers, cups, and sugar in this kitchen. Foraging tasks involve collecting multiple instances of targets. For example, collecting the berries from the bush. Finally, hybrid foraging involves collecting multiple instances of several types of target. For example, a child might pick all the raisins, nuts, and seeds out of his muesli.
Other than simplified standard laboratory search paradigms, which are made of brief trial structures and abstract stimulus material, these extended search tasks are more complex, extend over time, and use realistic image material – thus, are more akin to real-world searches. The task structure and eclectic analysis of the collected data allowed us to look at adult age differences in multiple cognitive components (attention, memory, strategic decisions) embedded in these extended search tasks. Different from many previous aging studies that used simple, standard experimental tasks, our new results show that attention and memory functions in hybrid search tasks are largely preserved in healthy aging individuals. However, older adults appear to be less likely to learn and benefit from sequential regularities that can facilitate search in younger age. Furthermore, when the hybrid search task involves foraging for multiple target objects, strategic changes towards more conservative search-decisions make older adults less efficient searchers than younger adults.
With our first series of experiments, we succeeded to decompose and measure preserved functions and those affected by aging within complex search tasks. A very interesting and encouraging result was that hybrid search behavior was well-preserved in older observers. Besides some general slowing, older observers did not have problems searching for any of up to 64(!) items that they held in memory. This finding is relevant to advance neuropsychological understanding and assessment of age-related (and potentially other disease- related) changes in cognitive functioning. It suggests that the simplification of task structure and stimulus material used in most conventional tests may overestimate age-related deficits in more natural searches. Extended search tasks may therefore be a more appropriate “baseline” measure of cognitive abilities in healthy aging and could be particularly suited to differentiate between normal aging, subtle/early, and severe, clinically-relevant cognitive decline. Thus, in the future, the clinical relevance could now be tested by assessing individuals who report subjective memory decline and patients diagnosed with mild cognitive impairment, which is associated with memory problems and often proceeds to Alzheimer’s disease.
In the final phase of the project, we further aim at identifying neural correlates of age differences in hybrid search by combining experimental tasks with EEG. Several EEG-compatible paradigms have already been developed in the course of the project. In younger adults, using these paradigms, we identified distinct event-related potentials (ERPs) in the EEG that mark the involvement of working memory and long-term memory processes involved in hybrid search. We will now collect data of older sample groups and expect to find a stronger ERPs indicative of compensatory activity in high-performing older adults.