To Örebro University

There is general consensus that older age, even in the absence of neurological pathologies, comes with several cognitive challenges with some of the most severe effects being related to working memory ability. The ability to control proactive interference (PI) in working memory is lower in older age and has been suggested to, at least partly, account for age-related working memory decline. PI refers to memory interferences arising from previous, but outdated, information interfering with new, goal-relevant, information. Older age is also accompanied by alterations in the structure and function of the brain. However, how age-related differences in the ability to control PI are related to age-related neural alterations is not fully understood. The aim of this doctoral thesis was to explore the neural underpinnings of reduced ability to control PI in working memory in aging.

Study I found that white-matter integrity (WMI) is significantly associated with the ability to control PI, both cross-sectionally and longitudinally, and mediates the relationship between age – PI in older adult, in line with the cortical disconnection hypothesis. Study II found that hippocampal subfield volume is negatively associated with PI both cross-sectionally and longitudinally in older adults, in line with a hypothesized role of this region in controlling PI in working memory. Study III found that the ability to control PI is differentially associated with IFG-based and whole brain rsFC pattern in older, compared to younger, adults and these patterns were in line with compensation-based accounts of cognitive aging.

Collectively, the findings from the three studies support and extend previous findings by demonstrating that age-related differences and changes in brain structure and function associated with a reduced ability to control PI in working memory in older age.