Stereotypic persistent B cell receptor clonotypes in Alzheimer's Disease (preprint)

We constructed in silico B cell receptor (BCR) repertoires using peripheral blood (PB) samples collected from 44 Alzheimer's Disease (AD) patients at baseline and 37 patients at follow-up. For the control group (CG), we used BCR repertoire data from the chronologically collected PB samples of 55 healthy volunteers vaccinated with the SARS-CoV2 mRNA vaccine. AD patients shared 3,983 stereotypic BCR clonotypes not found in CG, and their degree of overlap between patient pairs were significantly higher than that of CG pairs, even with the SAS-CoV2 spike protein triggering a concerted BCR response. Many stereotypic AD patient-specific BCR clonotypes co-existed in more than four patients and persisted throughout the two sampling points. One of these BCR clonotypes encoded an antibody reactive to the A{beta}42 peptide. Our findings strongly suggest that AD patients are exposed to common (auto)antigens associated with disease pathology, and that their BCR repertoire signatures have high diagnostic potential.

SARS-CoV-2 Spike amyloid fibrils specifically and selectively accelerates amyloid fibril formation of human prion protein and the amyloid β peptide (preprint)

An increasing number of reports suggest an association between COVID-19 infection and initiation or acceleration of neurodegenerative diseases including Alzheimer's disease (AD) and Creutzfeldt-Jakob disease (CJD). Both these diseases and several other neurodegenerative diseases are caused by conversion of human proteins into a misfolded, aggregated amyloid fibril state. The fibril formation process is self-perpetuating by seeded conversion from preformed fibril seeds. We recently described a plausible mechanism for amyloid fibril formation of SARS-CoV-2 spike protein. Spike-protein formed amyloid fibrils upon cleavage by neutrophil elastase, abundant in the inflammatory response to COVID-19 infection. We here provide evidence of significant Spike-amyloid fibril seeded acceleration of amyloid formation of CJD associated human prion protein (HuPrP) using an in vitro conversion assay. By seeding the HuPrP conversion assay with other in vitro generated disease associated amyloid fibrils we demonstrate that this is not a general effect but a specific feature of spike-amyloid fibrils. We also showed that the amyloid fibril formation of AD associated A{beta}1-42 was accelerated by Spike-amyloid fibril seeds. Of seven different 20-amino acid long peptides, Spike532 (532NLVKNKCVNFNFNGLTGTGV551) was most efficient in seeding HuPrP and Spike601 (601GTNTSNQVAVLYQDVNCTEV620) was most effective in seeding A{beta}1-42, suggesting substrate dependent selectivity of the cross-seeding activity. Albeit purely in vitro, our data suggest that cross-seeding by Spike-amyloid fibrils can be implicated in the increasing number of reports of CJD, AD, and possibly other neurodegenerative diseases in the wake of COVID-19.

Impact of age and sex on neuroinflammation following SARS-CoV-2 infection in a murine model (preprint)

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the etiological agent for the worldwide COVID-19 pandemic, is known to infect people of all ages and both sexes. Senior populations have the greatest risk of severe disease, and sexual dimorphism in clinical outcomes has been reported in COVID-19. SARS-CoV-2 infection in humans can cause damage to multiple organ systems, including the brain. Neurological symptoms are widely observed in patients with COVID-19, with many survivors suffering from persistent neurological and cognitive impairment, potentially accelerating Alzheimer's disease. The present study aims to investigate the impact of age and sex on the neuroinflammatory response to SARS-CoV-2 infection using a mouse model. Wild-type C57BL/6 mice were inoculated, by intranasal route, with SARS-CoV-2 lineage B.1.351 variant known to infect mice. Older animals and in particular males exhibited a significantly greater weight loss starting at 4 dpi. In addition, male animals exhibited higher viral RNA loads and higher titers of infectious virus in the lung, which was particularly evident in males at 16 months of age. Notably, no viral RNA was detected in the brains of infected mice, regardless of age or sex. Nevertheless, expression of IL-6, TNF-, and CCL-2 in the lung and brain was increased with viral infection. An unbiased brain RNA-seq/transcriptomic analysis showed that SARS-CoV-2 infection caused significant changes in gene expression profiles in the brain, with innate immunity, defense response to virus, cerebravascular and neuronal functions, as the major molecular networks affected. The data presented in this study show that SARS-CoV-2 infection triggers a neuroinflammatory response despite the lack of detectable virus in the brain. Age and sex have a modifying effect on this pathogenic process. Aberrant activation of innate immune response, disruption of blood-brain barrier and endothelial cell integrity, and supression of neuronal activity and axonogenesis underlie the impact of SARS-CoV-2 infection on the brain. Understanding the role of these affected pathways in SARS-CoV-2 pathogenesis helps identify appropriate points of therapeutic interventions to alleviate neurological dysfunction observed during COVID-19.

The Human Microglia Atlas (HuMicA) Unravels Changes in Homeostatic and Disease-Associated Microglia Subsets across Neurodegenerative Conditions (preprint)

Dysregulated microglia activation, leading to neuroinflammation, is currently considered to be of major relevance in the development and progression of neurodegenerative diseases. The initial M1/M2 dual activation classification for microglia is now considered outdated. Even the "disease-associated microglia" (DAM) phenotype, firstly described in mice, has proven insufficient to precisely represent the multitude of microglia phenotypes in pathology. In this study, we have constructed a transcriptomic atlas of human brain immune cells by integrating single-nucleus (sn)RNA-seq datasets from multiple neurodegenerative conditions. Sixteen datasets were included, comprising 295 samples from patients with Alzheimer's disease, autism spectrum disorder, epilepsy, multiple sclerosis, Lewy body diseases, COVID-19, and healthy controls. The integrated Human Microglia Atlas (HuMicA) dataset included 60,557 nuclei and revealed 11 microglial subpopulations distributed across all pathological and healthy conditions. Among these, we identified four different homeostatic clusters as well as pathological phenotypes. These included two stages of early and late activation of the DAM phenotype and the disease-inflammatory macrophage (DIM) phenotype, which was recently described in mice, and is also present in human microglia, as indicated by our analysis. The high versatility of microglia is evident through changes in subset distribution across various pathologies, suggesting their contribution to the establishment of pathological phenotypes. Our analysis showed overall depletion of four substates of homeostatic microglia, and expansion of niche subpopulations within the DAM and DIM spectrum across distinct neurodegenerative pathologies. The HuMicA is an invaluable resource tool used to support further advances in the study of microglia biology through healthy and disease settings.

Invariant Scattering Transform for Medical Imaging (preprint)

Invariant scattering transform introduces new area of research that merges the signal processing with deep learning for computer vision. Nowadays, Deep Learning algorithms are able to solve a variety of problems in medical sector. Medical images are used to detect diseases brain cancer or tumor, Alzheimer's disease, breast cancer, Parkinson's disease and many others. During pandemic back in 2020, machine learning and deep learning has played a critical role to detect COVID-19 which included mutation analysis, prediction, diagnosis and decision making. Medical images like X-ray, MRI known as magnetic resonance imaging, CT scans are used for detecting diseases. There is another method in deep learning for medical imaging which is scattering transform. It builds useful signal representation for image classification. It is a wavelet technique; which is impactful for medical image classification problems. This research article discusses scattering transform as the efficient system for medical image analysis where it's figured by scattering the signal information implemented in a deep convolutional network. A step by step case study is manifested at this research work.

Cellular Metabolism: A Fundamental Component of Degeneration in the Nervous System.

It is estimated that, at minimum, 500 million individuals suffer from cellular metabolic dysfunction, such as diabetes mellitus (DM), throughout the world. Even more concerning is the knowledge that metabolic disease is intimately tied to neurodegenerative disorders, affecting both the central and peripheral nervous systems as well as leading to dementia, the seventh leading cause of death. New and innovative therapeutic strategies that address cellular metabolism, apoptosis, autophagy, and pyroptosis, the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), growth factor signaling with erythropoietin (EPO), and risk factors such as the apolipoprotein E (APOE-ε4) gene and coronavirus disease 2019 (COVID-19) can offer valuable insights for the clinical care and treatment of neurodegenerative disorders impacted by cellular metabolic disease. Critical insight into and modulation of these complex pathways are required since mTOR signaling pathways, such as AMPK activation, can improve memory retention in Alzheimer's disease (AD) and DM, promote healthy aging, facilitate clearance of ß-amyloid (Aß) and tau in the brain, and control inflammation, but also may lead to cognitive loss and long-COVID syndrome through mechanisms that can include oxidative stress, mitochondrial dysfunction, cytokine release, and APOE-ε4 if pathways such as autophagy and other mechanisms of programmed cell death are left unchecked.

Navigating the Complexities of Dementia Care: The Lived Experiences of Black American Family Caregivers.

Black American individuals have a higher rate of Alzheimer's disease and related dementias (ADRD) diagnoses compared to other racial/ethnic groups, and their family caregiver population is expected to increase rapidly over the next 2 decades. The current study aimed to explore Black American women's experiences caring for family members with ADRD. An interpretative phenomenology approach was used to gain a deeper understanding of the caregiving experiences of Black American women. Participants in the study were all Black American married women aged 63 to 81 years (mean = 71.3 years, SD = 6.6 years). Key themes that emerged from the study included: (a) Family Care Obligation, (b) Caregiving Journey, (c) Prioritizing Health Concerns, (d) Coping Behaviors, and (e) Support Needs and Challenges. Family caregivers require ongoing support, education, and guidance. Implications for nursing practice include focusing on family assessments, increased education and awareness, and collaboration with interdisciplinary teams to provide the best resources. [Journal of Gerontological Nursing, 49(6), 19-26.].

The functional and structural changes in the hippocampus of COVID-19 patients.

Since the hippocampus is predominantly susceptible to injuries caused by COVID-19, there are increasing data indicating the likelihood of post-infection memory loss and quickening neurodegenerative disorders, such as Alzheimer's disease. This is due to the fact that the hippocampus has imperative functions in spatial and episodic memory as well as learning. COVID-19 activates microglia in the hippocampus and induces a CNS cytokine storm, leading to loss of hippocampal neurogenesis. The functional and structural changes in the hippocampus of COVID-19 patients can explain neuronal degeneration and reduced neurogenesis in the human hippocampus. This will open a window to explain memory and cognitive dysfunctions in "long COVID" through the resultant loss of hippocampal neurogenesis.

Proteomic landscape of astrocytes and pericytes infected with HIV/SARS-CoV-2 mono/co-infection, impacting on neurological complications (preprint)

Background Although most individuals recover from coronavirus disease 2019 (COVID-19) within a few weeks, some people continue to experience a wide range of symptoms known as post-acute sequelae of SARS-CoV-2 (PASC) or long COVID. Majority of patients with PASC develop neurological disorders like brain fog, fatigue, mood swings, sleep disorders, loss of smell and test among others collectively called neuro-PASC. While the people living with HIV (PWH) do not have a higher risk of developing severe disease and mortality/morbidity due to COVID-19. As a large section of PWH suffered from HIV-associated neurocognitive disorders (HAND), it is essential to understand the impact of neuro-PASC on people with HAND. In pursuit of this, we infected HIV/SARS-CoV-2 alone or together in primary human astrocytes and pericytes and performed proteomics to understand the impact of co-infection in the central nervous system.Methods Primary human astrocytes and pericytes were infected with SARS-CoV-2 or HIV or HIV + SARS-CoV-2. The concentration of HIV and SARS-CoV-2 genomic RNA in the culture supernatant was quantified using reverse transcriptase quantitative real time polymerase chain reaction (RT-qPCR). This was followed by a quantitative proteomics analysis of mock, HIV, SARS-CoV-2, and HIV + SARS-CoV-2 infected astrocytes and pericytes to understand the impact of the virus in CNS cell types.Results Both healthy and HIV-infected astrocytes and pericytes support abortive/low level of SARS-CoV-2 replication. In both mono-infected and co-infected cells, we observe a modest increase in the expression of SARS-CoV-2 host cell entry factors (ACE2, TMPRSS2, NRP1, and TRIM28) and inflammatory mediators (IL-6, TNF-α, IL-1β and IL-18). Quantitative proteomic analysis has identified uniquely regulated pathways in mock vs SARS-CoV-2, mock vs HIV + SARS-CoV-2, and HIV vs HIV + SARS-CoV-2 infected astrocytes and pericytes. The gene set enrichment analysis revealed that the top ten enriched pathways are linked to several neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis.Conclusions Our study emphasizes the significance of long-term monitoring of patients co-infected with HIV and SARS-CoV-2 to detect and understand the development of neurological abnormalities. By unraveling the molecular mechanisms involved, we can identify potential targets for future therapeutic interventions.

Social genomics, cognition, and well-being during the COVID-19 pandemic (preprint)

Introduction - Adverse psychosocial Adverse psychosocial exposure is associated with increased proinflammatory gene expression and reduced type-1 interferon gene expression, a profile known as the conserved transcriptional response to adversity (CTRA). Little is known about CTRA activity in the context of cognitive impairment, although chronic inflammatory activation has been posited as one mechanism contributing to late-life cognitive decline. Methods - We studied 171 community-dwelling older adults from the Wake Forest Alzheimers Disease Research Center who answered questions via a telephone questionnaire battery about their perceived stress, loneliness, well-being, and impact of COVID-19 on their life, and who provided a self-collected dried blood spot sample. Of those, 148 had adequate samples for mRNA analysis, and 143 were included in the final analysis, which including participants adjudicated as having normal cognition (NC, n = 91) or mild cognitive impairment (MCI, n = 52) were included in the analysis. Mixed effect linear models were used to quantify associations between psychosocial variables and CTRA gene expression. Results - In both NC and MCI groups, eudaimonic well-being (typically associated with a sense of purpose) was inversely associated with CTRA gene expression whereas hedonic well-being (typically associated with pleasure seeking) was positively associated. In participants with NC, coping through social support was associated with lower CTRA gene expression, whereas coping by distraction and reframing was associated with higher CTRA gene expression. CTRA gene expression was not related to coping strategies for participants with MCI, or to either loneliness or perceived stress in either group. Discussion - Eudaimonic and hedonic well-being remain important correlates of molecular markers of stress, even in people with MCI. However, prodromal cognitive decline appears to moderate the significance of coping strategies as a correlate of CTRA gene expression. These results suggest that MCI can selectively alter biobehavioral interactions in ways that could potentially affect the rate of future cognitive decline and may serve as targets for future intervention efforts.

Digital health technologies and Alzheimer's disease clinical trials: might decentralized clinical trials increase participation by people with cognitive impairment?

BACKGROUND: Therapeutic trials in Alzheimer's disease (AD) face many obstacles-particularly with regard to screening and recruitment. DISCUSSION: Decentralized clinical trials (DCTs) are being developed in other diseases and appear to be of value for overcoming these difficulties. The use of remote visits offers hope of broader recruitment and thus a reduction in inequalities due to age, geography, and ethnicity. Furthermore, it might be easier to involve primary care providers and caregivers in DCTs. However, further studies are needed to determine the feasibility of DCTs in AD. A mixed-model DCT might constitute the first step towards completely remote trials in AD and should be assessed first.

Incidence of Newly-Diagnosed Dementia After COVID-19 Infection versus Acute Upper Respiratory Infection: A Retrospective Cohort Study.

BACKGROUND: There is emerging evidence that coronavirus disease 2019 (COVID-19) is giving rise to seemingly unrelated clinical conditions long after the infection has resolved. OBJECTIVE: The aim of this study is to examine whether COVID-19 is associated with an increased risk of dementia including Alzheimer's disease. METHODS: This retrospective cohort study is based on longitudinal data from the IQVIATM Disease Analyzer database and included patients aged≥65 with an initial diagnosis of COVID-19 or acute upper respiratory infection (AURI) from 1,293 general practitioner practices between January 2020 and November 2021. AURI patients were matched 1 : 1 with COVID-19 patients using propensity scores based on sex, age, index quarter, health insurance type, the number of doctor visits, and comorbidities associated with dementia risk. Incidence rates of newly-diagnosed dementia were calculated using the person-years method. Poisson regression models were used to compute the incidence rate ratios (IRR). RESULTS: The present study included 8,129 matched pairs (mean age 75.1 years, 58.9% females). After 12 months of follow-up, 1.84% of the COVID-19 patients and 1.78% of the AURI patients had been diagnosed with dementia. The Poisson regression model resulted in an IRR of 1.05 (95% CI: 0.85-1.29). CONCLUSION: This study did not find any association between COVID-19 infection and one-year dementia incidence after controlling for all common risk factors for dementia. Because dementia is a progressive disease, which can be difficult to diagnose, a longer follow-up period might offer a better insight into a possible association between COVID-19 infection and an increased incidence of dementia cases in the future.

"Please Don't Forget Us": A Descriptive Qualitative Study of Caregivers of Older Adults With Alzheimer's Disease and Related Dementias During the COVID-19 Pandemic.

The current descriptive qualitative study explored the perceived impact of the coronavirus disease 2019 pandemic on sleep disturbances and nighttime agitation; the reported use of antipsychotics and other sedating medications; and the overall well-being of older adults with Alzheimer's disease and related dementias (ADRD) and their caregivers. One investigator conducted in-depth, phone interviews with caregivers of nursing home residents with ADRD (four family caregivers [FCs], three nurse practitioners [NPs]) and seven FCs of older adults with ADRD who lived with them at home. Caregivers described multiple sleep disturbances. Nighttime agitation symptoms were perceived to continue or worsen, and sedating medications and nonpharmacological interventions were required. Adverse impacts on reported well-being were significant, and impacts were grouped into emotional, social, and physical themes. Caregivers said, "Please don't forget us," and requested telehealth support for those at home and technology and human resources for nursing homes to reduce adverse impacts. [Research in Gerontological Nursing, 15(5), 217-228.].

New Alzheimer Disease Drugs, Long COVID and the Central Nervous System, and a Nasal Spray for Migraines-Highlights From the 2023 American Academy of Neurology Conference.

This Medical News article discusses research presented at the recent American Academy of Neurology Conference.

Anti-dementia drugs: a descriptive study of the prescription pattern in Italy.

INTRODUCTION: Acetylcholinesterase inhibitors (AChEIs) and memantine are currently the only anti-dementia drugs (ADDs) approved for treating Alzheimer's disease (AD) in Italy. This nationwide study aims to characterize dementia drug utilization in a population > 65 years, during 2018-2020. METHODS: Different administrative healthcare databases were queried to collect both aggregate and individual data. RESULTS: ADD consumption remained stable throughout the study period (~ 9 DDD/1000 inhabitants per day). AChEI consumption was over 5 DDD/1000 inhabitants per day. Memantine consumption was nearly 4 DDD/1000 inhabitants per day, representing 40% of ADD consumption. The prevalence of use of memantine represented nearly half of ADD consumption, substantially unchanged over the 3 years. Comparing the AD prevalence with the prevalence of ADDs use, the gap becomes wider as age increases. In 2019, the proportion of private purchases of ADDs was 38%, mostly represented by donepezil and rivastigmine. In 2020, memantine was the only ADD with an increase in consumption (Δ% 19-20, 1.3%). DISCUSSION: To our knowledge, this study represents the first attempt to investigate the ADD prescription pattern in Italy with a Public Health approach. In 2019, the proportion of ADD private purchases point out several issues concerning the reimbursability of ADDs. From a regulatory perspective, ADDs can be reimbursed by the National Health System only to patients diagnosed with AD; therefore, the off-label use of ADDs in patients with mild cognitive impairment may partially explain this phenomenon. The study extends knowledge on the use of ADDs, providing comparisons with studies from other countries that investigate the prescription pattern of ADDs.

Dementia, infections and vaccines: 30 years of controversy.

This paper reports the proceedings of a virtual meeting convened by the European Interdisciplinary Council on Ageing (EICA), to discuss the involvement of infectious disorders in the pathogenesis of dementia and neurological disorders leading to dementia. We recap how our view of the infectious etiology of dementia has changed over the last 30 years in light of emerging evidence, and we present evidence in support of the implication of infection in dementia, notably Alzheimer's disease (AD). The bacteria and viruses thought to be responsible for neuroinflammation and neurological damage are reviewed. We then review the genetic basis for neuroinflammation and dementia, highlighting the genes that are currently the focus of investigation as potential targets for therapy. Next, we describe the antimicrobial hypothesis of dementia, notably the intriguing possibility that amyloid beta may itself possess antimicrobial properties. We further describe the clinical relevance of the gut-brain axis in dementia, the mechanisms by which infection can move from the intestine to the brain, and recent findings regarding dysbiosis patterns in patients with AD. We review the involvement of specific pathogens in neurological disorders, i.e. SARS-CoV-2, human immunodeficiency virus (HIV), herpes simplex virus type 1 (HSV1), and influenza. Finally, we look at the role of vaccination to prevent dementia. In conclusion, there is a large body of evidence supporting the involvement of various infectious pathogens in the pathogenesis of dementia, but large-scale studies with long-term follow-up are needed to elucidate the role that infection may play, especially before subclinical or clinical disease is present.

SARS-CoV-2 infection leads to Tau pathological signature in neurons (preprint)

Background: The coronavirus disease 19 (COVID-19) has represented an issue for global health since its outbreak in March 2020. It is now evident that the SARS-CoV-2 infection results in a wide range of long-term neurological symptoms and is worryingly associated with the aggravation of Alzheimer's disease. Little is known about the molecular basis of these manifestations. Methods: Several SARS-CoV-2 strain variants were used to infect SH-SY5Y neuroblastoma cells and K18-hACE C57BL/6J mice. The Tau phosphorylation profile and aggregation propensity upon infection were investigated using immunoblot and immunofluorescence on cellular extracts, subcellular fractions, and brain tissue. The viral proteins Spike, Nucleocapsid, and Membrane were overexpressed in SH-SY5Y cells and the direct effect on Tau phosphorylation was checked using immunoblot experiments. Results: Upon infection, Tau is phosphorylated at several pathological epitopes associated with Alzheimer's disease and other tauopathies. Moreover, this event increases Tau's propensity to form insoluble aggregates and alters its subcellular localization. Conclusions: Our data support the evidence that SARS-CoV-2 infection in the Central Nervous System triggers downstream effects altering Tau function, eventually leading to the impairment of neuronal function.

Impact of COVID-19 Mandatory Lockdown Measures on Cognitive and Neuropsychiatric Symptoms in Persons with Alzheimer's Disease in Lima, Peru.

BACKGROUND: Neuropsychiatric symptoms (NPS) in patients with Alzheimer's disease (AD) worsened during the COVID-19 lockdowns, but their progression thereafter is unknown. We present the first longitudinal study tracking them before, during, and after restrictions. OBJECTIVES: To describe the effect of the COVID-19 mandatory lockdowns on Cognitive and Neuropsychiatric symptoms in patients with Mild Cognitive Impairment (MCI) and Alzheimer's Disease (AD). METHODS: Cohort of 48 patients with amnestic MCI and 38 with AD in Lima, Peru. They received three rounds of cognitive (RUDAS, CDR, M@T), behavioral (NPI), and functional (ADCS-ADL) assessments. We assessed the change in score means across the time points and for each domain of NPS and tracked the changes in individual patients. RESULTS: RUDAS declined 0.9 (SD 1.0) from baseline to lockdown and 0.7 (SD 1.0) after restrictions. M@T declined 1.0 (SD 1.5) from baseline to lockdown and 1.4 (SD 2.0) after restrictions. CDR worsened in 72 patients (83.72%) from baseline to post-lockdown. NPI worsened by 10 (SD 8.3) from baseline to lockdown but improved by 4.8 (SD 6.4) after restrictions. Proportionally, 81.3% of all patients had worsened NPS during the lockdowns, but only 10.7% saw an increase thereafter. Improvement was statistically significant for specific NPS domains except hallucinations, delusions, and appetite changes. Anxiety, irritability, apathy, and disinhibition returned to baseline levels. CONCLUSION: Following confinement, cognition continued to decline, but NPS demonstrated either stability or improvement. This highlights the role modifiable risk factors may have on the progression of NPS.

Steeper memory decline after COVID-19 lockdown measures.

BACKGROUND: During COVID-19 lockdown measures, memory clinic patients reported worries for faster cognitive decline, due to loss of structure and feelings of loneliness and depression. We aimed to investigate the impact of the COVID-19 lockdown on rate of cognitive decline in a mixed memory clinic population, compared to matched historical controls. METHODS: We included patients who visited Alzheimer Center Amsterdam 6 months to 1 week before the first Dutch COVID-19 lockdown, and had a second visit 1 year later, after this lockdown period (n = 113; 66 ± 7 years old; 30% female; n = 55 dementia, n = 31 mild cognitive impairment (MCI), n = 18 subjective cognitive decline (SCD), n = 9 postponed diagnosis). Historical controls (visit in 2016/2017 and second visit 1 year later (n = 640)) were matched 1:1 to lockdown patients by optimal Mahalanobis distance matching (both groups n = 113). Groups were well matched. Differences between lockdown patients and historical controls over time in Mini-Mental State Examination, Trail Making Test part A and B, Rey-Auditory Verbal Learning Test (RAVLT) immediate and delayed recall, and category fluency scores were analyzed using linear mixed effect models with random intercepts. We examined differences in rate of cognitive decline between whole groups, and after stratification in SCD, MCI, and dementia separately. RESULTS: Lockdown patients had a faster rate of memory decline compared to controls on both RAVLT immediate [B(SE) = - 2.62 (1.07), p = 0.015] and delayed recall [B(SE) = - 1.07 (0.34), p = 0.002]. Stratification by syndrome diagnosis showed that this effect was largely attributable to non-demented participants, as we observed faster memory decline during lockdown in SCD and MCI (RAVLT immediate [SCD: B(SE) = - 6.85 (2.97), p = 0.027; MCI: B(SE) = - 6.14 (1.78), p = 0.001] and delayed recall [SCD: B(SE) = - 2.45 (1.11), p = 0.035; MCI: B(SE) = - 1.50 (0.51), p = 0.005]), but not in dementia. CONCLUSION: Memory clinic patients, specifically in pre-dementia stages, showed faster memory decline during COVID-19 lockdown, providing evidence that lockdown regulations had a deleterious effect on brain health. In individuals that may have been able to deal with accumulating, subclinical neuropathology under normal and structured circumstances, the additional stress of lockdown regulations may have acted as a "second hit," resulting in less beneficial disease trajectory.