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Olfactory impairment has emerged as a potent marker of future dementia and cognitive impairment. The underlying biological mechanisms for this olfaction-dementia link remain, however, largely unexplored. Recent technological developments have made assessment of biomarkers (e.g. amyloid β, tau) of Alzheimer’s disease (AD) more easily accessible. These new blood-based biomarkers (BBB) can help identify age- and dementia-related changes and understanding the link between cognitive and olfactory decline and future dementia development. This project will investigate the longitudinal trajectories of cognitive and olfactory abilities in relation to aging and dementia and a range of dementia biomarkers. We will target 4 main areas: associations between 1) AD biomarkers and cognitive and olfactory decline in aging and across the preclinical dementia spectrum, 2) AD biomarkers and starting point and rate of cognitive and olfactory decline in relation to a future dementia diagnosis, 3) olfactory impairment and incident dementia across different biomarker profiles, and 4) cross-sectional links between BBB of AD, neuroimaging markers, and specific memory and olfactory abilities in a newly added cohort. We will use data from a Swedish population-based study-SNAC-K, with extensive biomarker assessment at baseline and repeated measures of olfaction, cognition and dementia across &gt

20 years. The project will lead to new and important knowledge regarding the olfaction-dementia association.

Long-lasting post-COVID symptoms have severe implications for affected individuals, the healthcare system, and society as a whole. This project focuses on two common symptoms in this patient group, cognitive and olfactory deficits. We aim to increase the knowledge regarding (a) long-term effects (up to 3 years) on cognitive and olfactory function after mild COVID-19, (b) factors associated with recovering from such deficits, (c) neurological bases of cognitive and olfactory deficits, and (d) associations between remaining deficits and returning to previous levels of functioning and activities (e.g. work). The proposed project is a follow-up of an ongoing study

following these patients over time is critical for understanding the long-term effects. The project consists of 3 parts: (1) Longitudinal follow-up of a clinical sample of post-COVID patients following mild COVID-19 with a third cognitive, olfactory, and functional assessment, (2) A second magnetic resonance imaging assessment of a subgroup of this sample and matched controls, (3) A new online questionnaire targeting functioning and well-being of a large sample of post-COVID patients, diagnosed during the first years of the pandemic. Together, the results of this project will provide important new knowledge regarding the long-term effects of COVID-19 on cognitive and olfactory performance, which factors may affect the development in these domains over time, and how they relate to functioning in everyday life.

Long-lasting post-COVID symptoms may have severe implications for affected individuals and the healthcare system. This project focuses on two common symptoms in this patient group, cognitive and olfactory deficits. We aim to increase the knowledge regarding (a) nature, severity, and duration of long-term effects on cognitive and olfactory function after mild COVID, (b) which individuals are more likely to be affected by and recover from such deficits, (c) underlying mechanisms, and (d) associations between these deficits and returning to previous levels of functioning. Longitudinal follow-up of these patients is vital to understand the long-term effects. It is further unknown how many individuals are affected by subclinical cognitive impairments following a COVID-19 infection. The project consists of 3 parts: (1) Longitudinal follow-up of a clinical sample (Danderyd rehabilitation medicine clinic) of post-COVID patients with repeated cognitive, olfactory, and functional assessments, (2) Magnetic resonance imaging assessments of a subgroup of this sample and a matched control group, (3) Repeated cognitive testing of a population sample comparing cognitive trajectories of persons with and without previous COVID-19. These data collections will provide important new knowledge regarding the long-term effects of COVID-19 on cognitive and olfactory performance, which factors may affect the longitudinal development in these domains, and how they relate to functioning in other areas.