Changes in self- and study partner-perceived cognitive functioning in relation to amyloid status and future clinical progression: Findings from the SCIENCe project.

INTRODUCTION: We investigated changes in self- and study partner-reported self-perceived cognitive decline in relation to amyloid pathology and clinical progression, in a sample of cognitively normal individuals. METHODS: A total of 404 participants (63 ± 9 years, 44% female) and their study partners completed the Cognitive Change Index (CCI) yearly (0.7-6.8 follow-up years; n visits = 1436). Baseline and longitudinal associations between (change in) CCI scores, amyloid, and clinical progression were modeled in linear mixed models and Cox regressions. RESULTS: CCI-study partner scores of amyloid-positive individuals increased over time (B = 1.79, 95% confidence interval [CI] = [0.51, 3.06]), while CCI-self scores remained stable (B = -0.45, 95% CI = [-1.77, 0.87]). Ten-point higher baseline CCI-study partner (hazard ratio [HR] = 1.75, 95% CI = [1.30, 2.36]) and CCI-self scores (HR = 1.90, 95% CI = [1.40, 2.58]) were associated with an approximately 2-fold increased risk of progression to mild cognitive impairment or dementia. DISCUSSION: Study partner-reported but not self-perceived complaints increase over time in amyloid-positive individuals, supporting the value of longitudinal study partner report, even in initially cognitively normal individuals.

Cerebral blood flow, amyloid burden, and cognition in cognitively normal individuals.

PURPOSE: The role of cerebral blood flow (CBF) in the early stages of Alzheimer's disease is complex and largely unknown. We investigated cross-sectional and longitudinal associations between CBF, amyloid burden, and cognition, in cognitively normal individuals with subjective cognitive decline (SCD). METHODS: We included 187 cognitively normal individuals with SCD from the SCIENCe project (65 ± 8 years, 39% F, MMSE 29 ± 1). Each underwent a dynamic (0-70 min) [18F]florbetapir PET and T1-weighted MRI scan, enabling calculation of mean binding potential (BPND; specific amyloid binding) and R1 (measure of relative (r)CBF). Eighty-three individuals underwent a second [18F]florbetapir PET (2.6 ± 0.7 years). Participants annually underwent neuropsychological assessment (follow-up time 3.8 ± 3.1 years; number of observations n = 774). RESULTS: A low baseline R1 was associated with steeper decline on tests addressing memory, attention, and global cognition (range betas 0.01 to 0.27, p < 0.05). High BPND was associated with steeper decline on tests covering all domains (range betas - 0.004 to - 0.70, p < 0.05). When both predictors were simultaneously added to the model, associations remained essentially unchanged. Additionally, we found longitudinal associations between R1 and BPND. High baseline BPND predicted decline over time in R1 (all regions, range betasBP×time - 0.09 to - 0.14, p < 0.05). Vice versa, low baseline R1 predicted increase in BPND in frontal, temporal, and composite ROIs over time (range betasR1×time - 0.03 to - 0.08, p < 0.05). CONCLUSION: Our results suggest that amyloid accumulation and decrease in rCBF are two parallel disease processes without a fixed order, both providing unique predictive information for cognitive decline and each process enhancing the other longitudinally.

Longitudinal change in ATN biomarkers in cognitively normal individuals.

BACKGROUND: Biomarkers for amyloid, tau, and neurodegeneration (ATN) have predictive value for clinical progression, but it is not clear how individuals move through these stages. We examined changes in ATN profiles over time, and investigated determinants of change in A status, in a sample of cognitively normal individuals presenting with subjective cognitive decline (SCD). METHODS: We included 92 individuals with SCD from the SCIENCe project with [18F]florbetapir PET (A) available at two time points (65 ± 8y, 42% female, MMSE 29 ± 1, follow-up 2.5 ± 0.7y). We additionally used [18F]flortaucipir PET for T and medial temporal atrophy score on MRI for N. Thirty-nine individuals had complete biomarker data at baseline and follow-up, enabling the construction of ATN profiles at two time points. All underwent extensive neuropsychological assessments (follow-up time 4.9 ± 2.8y, median number of visits n = 4). We investigated changes in biomarker status and ATN profiles over time. We assessed which factors predisposed for a change from A- to A+ using logistic regression. We additionally used linear mixed models to assess change from A- to A+, compared to the group that remained A- at follow-up, as predictor for cognitive decline. RESULTS: At baseline, 62% had normal AD biomarkers (A-T-N- n = 24), 5% had non-AD pathologic change (A-T-N+ n = 2,) and 33% fell within the Alzheimer's continuum (A+T-N- n = 9, A+T+N- n = 3, A+T+N+ n = 1). Seventeen subjects (44%) changed to another ATN profile over time. Only 6/17 followed the Alzheimer's disease sequence of A → T → N, while 11/17 followed a different order (e.g., reverted back to negative biomarker status). APOE ε4 carriership inferred an increased risk of changing from A- to A+ (OR 5.2 (95% CI 1.2-22.8)). Individuals who changed from A- to A+, showed subtly steeper decline on Stroop I (ß - 0.03 (SE 0.01)) and Stroop III (- 0.03 (0.01)), compared to individuals who remained A-. CONCLUSION: We observed considerable variability in the order of ATN biomarkers becoming abnormal. Individuals who became A+ at follow-up showed subtle decline on tests for attention and executive functioning, confirming clinical relevance of amyloid positivity.

Subjective cognitive decline and self-reported sleep problems: The SCIENCe project.

We aim to investigate the frequency and type of sleep problems in memory clinic patients with subjective cognitive decline (SCD) and their association with cognition, mental health, brain magnetic resonance imaging (MRI), and cerebrospinal fluid (CSF) biomarkers. Three hundred eight subjects (65 ± 8 years, 44% female) were selected from the Subjective Cognitive Impairment Cohort (SCIENCe) project. All subjects answered two sleep questionnaires, Berlin Questionnaire (sleep apnea) and Pittsburgh Sleep Quality Index (sleep quality) and underwent a standardized memory clinic work-up. One hundred ninety-eight (64%) subjects reported sleep problems, based on 107 (35%) positive screenings on sleep apnea and 162 (53%) on poor sleep quality. Subjects with sleep problems reported more severe depressive symptoms, more anxiety, and more severe SCD. Cognitive tests, MRI, and CSF biomarkers did not differ between groups. Our results suggest that improvement of sleep quality and behaviors are potential leads for treatment in many subjects with SCD to relieve the experienced cognitive complaints.

Association of CSF, Plasma, and Imaging Markers of Neurodegeneration With Clinical Progression in People With Subjective Cognitive Decline.

BACKGROUND AND OBJECTIVES: Multiple biomarkers have been suggested to measure neurodegeneration (N) in the AT(N) framework, leading to inconsistencies between studies. We investigated the association of 5 N biomarkers with clinical progression and cognitive decline in individuals with subjective cognitive decline (SCD). METHODS: We included individuals with SCD from the Amsterdam Dementia Cohort and SCIENCe project, a longitudinal cohort study (follow-up 4±3 years). We used the following N biomarkers: CSF total tau (t-tau), medial temporal atrophy visual rating on MRI, hippocampal volume (HV), serum neurofilament light (NfL), and serum glial fibrillary acidic protein (GFAP). We determined correlations between biomarkers. We assessed associations between N biomarkers and clinical progression to mild cognitive impairment or dementia (Cox regression) and Mini-Mental State Examination (MMSE) over time (linear mixed models). Models included age, sex, CSF ß-amyloid (Aß) (A), and CSF p-tau (T) as covariates, in addition to the N biomarker. RESULT: We included 401 individuals (61±9 years, 42% female, MMSE 28 ± 2, vascular comorbidities 8%-19%). N biomarkers were modestly to moderately correlated (range r -0.28 - 0.58). Serum NfL and GFAP correlated most strongly (r 0.58, p < 0.01). T-tau was strongly correlated with p-tau (r 0.89, p < 0.01), although these biomarkers supposedly represent separate biomarker groups. All N biomarkers individually predicted clinical progression, but only HV, NfL, and GFAP added predictive value beyond Aß and p-tau (hazard ratio 1.52 [95% CI 1.11-2.09]; 1.51 [1.05-2.17]; 1.50 [1.04-2.15]). T-tau, HV, and GFAP individually predicted MMSE slope (range ß -0.17 to -0.11, p < 0.05), but only HV remained associated beyond Aß and p-tau (ß -0.13 [SE 0.04]; p < 0.05). DISCUSSION: In cognitively unimpaired older adults, correlations between different N biomarkers were only moderate, indicating they reflect different aspects of neurodegeneration and should not be used interchangeably. T-tau was strongly associated with p-tau (T), which makes it less desirable to use as a measure for N. HV, NfL, and GFAP predicted clinical progression beyond A and T. Our results do not allow to choose one most suitable biomarker for N, but illustrate the added prognostic value of N beyond A and T. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that HV, NfL, and GFAP predicted clinical progression beyond A and T in individuals with SCD.

Association of the ATN Research Framework With Clinical Profile, Cognitive Decline, and Mortality in Patients With Dementia With Lewy Bodies.

BACKGROUND AND OBJECTIVES: The ATN framework has been developed to categorize biological processes within the Alzheimer disease (AD) continuum. Because AD pathology often coincides with dementia with Lewy bodies (DLB), we aimed to investigate the distribution of ATN profiles in DLB and associate ATN profiles in DLB with prognosis. METHODS: We included 202 patients with DLB from the Amsterdam Dementia Cohort (68±7 years; 19% female; Mini-Mental State Examination 24 ± 3; abnormal DAT-SPECT 105/119). Patients were classified into 8 profiles according to the ATN framework, using CSF ß-amyloid (Aß)42 (A), CSF p-tau (T), and medial temporal atrophy scores (N). We compared presence of clinical symptoms in ATN profiles and used linear mixed models to analyze decline on cognitive tests (follow-up 3±2 years for n = 139). Mortality risk was assessed using Cox proportional hazards analysis. Analyses were performed on the 8 profiles as well as 3 clustered categories (normal AD biomarkers, non-AD pathologic change, and AD continuum). RESULTS: Fifty (25%) patients with DLB had normal AD biomarkers (A-T-N-), 37 (18%) had non-AD pathologic change (A-T+N- 10%, A-T-N+ 6%, A-T+N+ 3%), and 115 (57%) were classified within the AD continuum (A+T-N- 20%, A+T+N- 16%, A+T-N+ 10%, A+T+N+ 9%). A+T+N+ patients were older and least often had REM sleep behavior disorder symptoms. Parkinsonism was more often present in A+T- compared to A-T+ patients (independent of N). Compared to patients with normal AD biomarkers, patients in A+ categories showed steeper decline on memory tests and higher mortality risk. Cognitive decline and mortality did not differ between non-AD pathologic change and normal AD biomarkers. DISCUSSION: In our DLB cohort, we found clinically relevant associations between ATN categories and disease manifestation. Patients within the AD continuum had steeper cognitive decline and shorter survival. Implementing the ATN framework within patients with DLB aids in subtyping patients based on underlying biological processes and could provide targets for future treatment strategies (for example, AD-modifying treatment). Expanding the framework by incorporating markers for α-synucleinopathy would improve the use of the framework to characterize patients with dementia with mixed pathology, which could enhance proper stratification of patients for therapeutic trials.

BDNF-Met polymorphism and amyloid-beta in relation to cognitive decline in cognitively normal elderly: the SCIENCe project.

Brain-derived neurotrophic factor (BNDF) plays a role in synapse integrity. We investigated in 398 cognitively normal adults (60±8years, 41% female, MMSE=28±1) the joint association of the Val66Met polymorphism of the BDNF gene (Met+/-) and plasma BDNF levels and abnormal cerebrospinal fluid (CSF) amyloid-beta status (A+/-) with cognitive decline and dementia risk. Age-, sex- and education-adjusted linear mixed models showed that compared to Met-A-, Met+A+ showed steeper decline on tests of global cognition, memory, language, attention and executive functioning, while Met-A+ showed steeper decline on a smaller number of tests. There were no associations between Met+A- and cognitive decline. Cox models showed that compared to Met-A-, Met+A+ participants were at increased risk of dementia (HR=8.8, 95%CI: 2.8-27.9), as were Met-A+ participants (HR=6.5, 95%CI: 2.2-19.5). Lower plasma BDNF was associated with an increased risk of progression to dementia in the A+ participants. Our results imply that Met-carriage on top of amyloid-beta pathology might increase rate of cognitive decline to dementia.

Risk of dementia in APOE ε4 carriers is mitigated by a polygenic risk score.

INTRODUCTION: We investigated relationships among genetic determinants of Alzheimer's disease (AD), amyloid/tau/neurodegenaration (ATN) biomarkers, and risk of dementia. METHODS: We studied cognitively normal individuals with subjective cognitive decline (SCD) from the Amsterdam Dementia Cohort and SCIENCe project. We examined associations between genetic variants and ATN biomarkers, and evaluated their predictive value for incident dementia. A polygenic risk score (PRS) was calculated based on 39 genetic variants. The APOE gene was not included in the PRS and was analyzed separately. RESULTS: The PRS and APOE ε4 were associated with amyloid-positive ATN profiles, and APOE ε4 additionally with isolated increased tau (A-T+N-). A high PRS and APOE ε4 separately predicted AD dementia. Combined, a high PRS increased while a low PRS attenuated the risk associated with ε4 carriers. DISCUSSION: Genetic variants beyond APOE are clinically relevant and contribute to the pathophysiology of AD. In the future, a PRS might be used in individualized risk profiling.

Serum markers glial fibrillary acidic protein and neurofilament light for prognosis and monitoring in cognitively normal older people: a prospective memory clinic-based cohort study.

BACKGROUND: Serum glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) are putative non-amyloid blood-based biomarkers indicative of ongoing inflammatory and neurodegenerative disease processes. We aimed to assess their prognostic and monitoring value for progression to dementia in individuals presenting at a memory clinic who are cognitively normal. METHODS: For this prospective cohort study, we included individuals who were cognitively normal from the Amsterdam Dementia Cohort and received screening for dementia at first visit and annual follow-up visits. Participants without a serum sample stored in the Amsterdam Dementia Biobank within 6 months of baseline visit and without a follow-up diagnosis after a minimum of 6 months were excluded. We measured serum GFAP and NfL levels at baseline for all participants and at follow-up for a subset of participants. Using Cox proportional hazard models, we investigated associations of biomarker levels (Z-transformed) with incident dementia (adjusted for age and sex), by entering the markers first separately and then simultaneously, to test independent associations. We also assessed longitudinal performance of the markers on a standardised neuropsychological test battery covering global cognition, memory, language, executive functioning, and attention (adjusted for age, sex, and education). Finally, we evaluated the association of slopes of biomarker levels with incident dementia (adjusted for age and sex). FINDINGS: Between July 13, 2001, and Aug 17, 2016, 300 individuals were included in the study. Mean baseline age was 61 years (SD 9), 125 (42%) of participants were women, and mini-mental state examination was 29 (IQR 27-29). Median follow-up time was 3·0 years (IQR 1·9-4·2), with a median of three visits per participant (range 2-12; 1010 total neuropsychological evaluations). During follow-up, 27 (9%) of 300 individuals developed dementia. Both high baseline GFAP (hazard ratio 3·6, 95% CI 2·2-5·7; p<0·0001) and high baseline NfL (1·8, 1·2-2·8; p=0·0037) were associated with increased risk of dementia. When entering both markers simultaneously in the model, only GFAP remained associated with an increased risk of dementia (3·3, 1·9-5·5; p<0·0001). When additionally entering (inverted) plasma amyloid ß42/40, both GFAP (2·6, 1·4-5·0; p=0·0026) and amyloid ß42/40 (2·1, 1·2-3·6; p=0·0091) were independently associated with incident dementia whereas NfL was not (1·4, 0·8-2·5; p=0·28). Linear mixed models showed that higher baseline GFAP levels were associated with a steeper rate of decline in the domains of memory, attention, and executive functioning (pfalse discovery rate<0·05), whereas higher NfL levels were not. Repeated serum GFAP and NfL analyses revealed that NfL levels rose more steeply over time in individuals with incident dementia compared with those without (p=0·0006), whereas GFAP levels did not (p=0·074). INTERPRETATION: Our results suggest that, while serum NfL seems to have potential as monitoring biomarker, GFAP might be a valuable prognostic biomarker, predicting incident dementia. FUNDING: Alzheimer Nederland, Gieskes Strijbis Fonds.

ATN classification and clinical progression in subjective cognitive decline: The SCIENCe project.

OBJECTIVE: To investigate the relationship between the ATN classification system (amyloid, tau, neurodegeneration) and risk of dementia and cognitive decline in individuals with subjective cognitive decline (SCD). METHODS: We classified 693 participants with SCD (60 ± 9 years, 41% women, Mini-Mental State Examination score 28 ± 2) from the Amsterdam Dementia Cohort and Subjective Cognitive Impairment Cohort (SCIENCe) project according to the ATN model, as determined by amyloid PET or CSF ß-amyloid (A), CSF p-tau (T), and MRI-based medial temporal lobe atrophy (N). All underwent extensive neuropsychological assessment. For 342 participants, follow-up was available (3 ± 2 years). As a control population, we included 124 participants without SCD. RESULTS: Fifty-six (n = 385) participants had normal Alzheimer disease (AD) biomarkers (A-T-N-), 27% (n = 186) had non-AD pathologic change (A-T-N+, A-T+N-, A-T+N+), 18% (n = 122) fell within the Alzheimer continuum (A+T-N-, A+T-N+, A+T+N-, A+T+N+). ATN profiles were unevenly distributed, with A-T+N+, A+T-N+, and A+T+N+ containing very few participants. Cox regression showed that compared to A-T-N-, participants in A+ profiles had a higher risk of dementia with a dose-response pattern for number of biomarkers affected. Linear mixed models showed participants in A+ profiles showed a steeper decline on tests addressing memory, attention, language, and executive functions. In the control group, there was no association between ATN and cognition. CONCLUSIONS: Among individuals presenting with SCD at a memory clinic, those with a biomarker profile A-T+N+, A+T-N-, A+T+N-, and A+T+N+ were at increased risk of dementia, and showed steeper cognitive decline compared to A-T-N- individuals. These results suggest a future where biomarker results could be used for individualized risk profiling in cognitively normal individuals presenting at a memory clinic.