How COVID-19 influenced disease trajectory in memory clinic patients: Lessons learned from the COVID-19 pandemic

Summary of Findings This thesis examined the psychosocial, cognitive, clinical, and healthcare-related impact of the COVID-19 pandemic on individuals with (pre-)dementia, cognitively normal memory clinic patients, caregivers, and the general population. Chapter 2 focused on psychosocial effects and lifestyle changes during the COVID-19 pandemic. In chapter 2.1, n=389 patients from the Amsterdam Dementia Cohort (ADC) and n=147 caregivers completed surveys during the first lockdown (April–July 2020). Both symptomatic and cognitively normal patients reported worries about accelerated cognitive decline and psychological symptoms. Several vulnerable groups were identified, including patients experiencing discontinued care, social isolation, and behavioral problems. These findings highlight the need for healthcare professionals to ensure continuity of care and strengthen support networks for patients and caregivers during restrictive measures. In chapter 2.2, n=511 (pre-)dementia patients and n=826 caregivers completed surveys during the second lockdown (December 2020–March 2021). Compared to the first lockdown, psychosocial and behavioral problems decreased, and perceived social support increased. Support from family and friends emerged as a key protective factor. These results suggest adaptation over time and underline the importance of social support in mitigating negative outcomes. In chapter 2.3, n=17,773 cognitively healthy individuals from the Dutch Brain Research Registry reported lifestyle changes during the pandemic. The pandemic affected lifestyle both positively (e.g., healthier diet, increased physical activity, reduced alcohol consumption) and negatively (e.g., loneliness, sleep problems, reduced activity). Certain (socio)demographic groups were more vulnerable to detrimental changes in modifiable brain health risk factors. Chapter 3 investigated disease progression and mortality during the pandemic using historical control designs. In chapter 3.1, memory clinic patients assessed during COVID-19 showed faster memory decline, particularly in pre-dementia stages, compared to matched historical controls (both groups n=113). This suggests that lockdown-related stress may have negatively affected cognitive trajectories, acting as a “second hit” in vulnerable individuals. In chapter 3.2, all-cause mortality was compared between n=923 pandemic patients and n=830 historical controls. Patients with dementia had a higher mortality risk during the pandemic, largely attributable to COVID-19 infection itself rather than indirect effects of restrictive measures. Chapter 4 examined the impact of the COVID-19 pandemic on healthcare consumption. In chapter 4.1, ADC memory clinic patients were included (n = 911 pandemic; n = 821 historical controls). Dementia patients had a shorter time to institutionalization during the pandemic, while total healthcare costs were similar for (pre-)dementia patients before and during COVID-19. In chapter 4.2, geriatric outpatients from Northwest Clinics were analyzed (n = 5,005 pandemic; n = 5,636 controls). Fewer patients visited secondary care during the pandemic; among those assessed cognitively, more were diagnosed with MCI or dementia, fewer were cognitively normal, and MoCA scores were lower, with no differences in MMSE or nutritional status. Conclusion: The COVID-19 pandemic had substantial psychosocial, cognitive, and clinical consequences, particularly for vulnerable populations such as individuals with (pre-)dementia and their caregivers. Social support proved crucial in reducing negative outcomes. These findings emphasize the importance of safeguarding continuity of care, monitoring cognitive health, and strengthening support systems during future societal crises.