Characterization of symptoms and determinants of disease burden in dementia with Lewy bodies: DEvELOP design and baseline results.

BACKGROUND: The DEmEntia with LEwy bOdies Project (DEvELOP) aims to phenotype patients with dementia with Lewy bodies (DLB) and study the symptoms and biomarkers over time. Here, we describe the design and baseline results of DEvELOP. We investigated the associations between core and suggestive DLB symptoms and different aspects of disease burden, i.e., instrumental activities of daily living (IADL) functioning, quality of life (QoL), and caregiver burden. METHODS: We included 100 DLB patients (69 ± 6 years, 10%F, MMSE 25 ± 3) in the prospective DEvELOP cohort. Patients underwent extensive assessment including MRI, EEG/MEG, 123FP-CIT SPECT, and CSF and blood collection, with annual follow-up. Core (hallucinations, parkinsonism, fluctuations, RBD) and suggestive (autonomous dysfunction, neuropsychiatric symptoms) symptoms were assessed using standardized questionnaires. We used multivariate regression analyses, adjusted for age, sex, and MMSE, to evaluate how symptoms related to the Functional Activities Questionnaire, QoL-AD questionnaire, and Zarit Caregiver Burden Interview. RESULTS: In our cohort, RBD was the most frequently reported core feature (75%), while visual hallucinations were least frequently reported (39%) and caused minimal distress. Suggestive clinical features were commonly present, of which orthostatic hypotension was most frequently reported (64%). Ninety-five percent of patients showed EEG/MEG abnormalities, 88% of 123FP-CIT SPECT scans were abnormal, and 53% had a CSF Alzheimer's disease profile. Presence of fluctuations, lower MMSE, parkinsonism, and apathy were associated with higher IADL dependency. Depression, constipation, and lower IADL were associated with lower QoL-AD. Apathy and higher IADL dependency predisposed for higher caregiver burden. CONCLUSION: Baseline data of our prospective DLB cohort show clinically relevant associations between symptomatology and disease burden. Cognitive and motor symptoms are related to IADL functioning, while negative neuropsychiatric symptoms and functional dependency are important determinants of QoL and caregiver burden. Follow-up is currently ongoing to address specific gaps in DLB research.

Sex-specific associations with cerebrospinal fluid biomarkers in dementia with Lewy bodies.

BACKGROUND: Dementia with Lewy bodies (DLB) is more prevalent in men than in women. In addition, post-mortem studies found sex differences in underlying pathology. It remains unclear whether these differences are also present antemortem in in vivo biomarkers, and whether sex differences translate to variability in clinical manifestation. The objective of this study was to evaluate sex differences in cerebrospinal fluid (CSF) biomarker concentrations (i.e., alpha-synuclein (α-syn), amyloid ß1-42 (Aß42), total tau (Tau), phosphorylated tau at threonine 181 (pTau)) and clinical characteristics in DLB. METHODS: We included 223 DLB patients from the Amsterdam Dementia Cohort, of which 39 were women (17%, age 70 ± 6, MMSE 21 ± 6) and 184 men (83%, age 68 ± 7, MMSE 23 ± 4). Sex differences in CSF biomarker concentrations (i.e., α-syn, Aß42, Tau, and pTau) were evaluated using age-corrected general linear models (GLM). In addition, we analyzed sex differences in core clinical features (i.e., visual hallucinations, parkinsonism, cognitive fluctuations, and REM sleep behavior disorder (RBD) and cognitive test scores using age- and education-adjusted GLM. RESULTS: Women had lower CSF α-syn levels (F 1429 ± 164 vs M 1831 ± 60, p = 0.02) and CSF Aß42 levels (F 712 ± 39 vs M 821 ± 18, p = 0.01) compared to men. There were no sex differences for (p) Tau concentrations (p > 0.05). Clinically, women were older, had a shorter duration of complaints (F 2 ± 1 vs M 4 ± 3, p < 0.001), more frequent hallucinations (58% vs 38%, p = 0.02), and scored lower on MMSE and a fluency task (MMSE, p = 0.02; animal fluency, p = 0.006). Men and women did not differ on fluctuations, RBD, parkinsonism, or other cognitive tests. CONCLUSIONS: Women had lower Aß42 and α-syn levels than men, alongside a shorter duration of complaints. Moreover, at the time of diagnosis, women had lower cognitive test scores and more frequent hallucinations. Based on our findings, one could hypothesize that women have a more aggressive disease course in DLB compared to men. Future research should investigate whether women and men with DLB might benefit from sex-specific treatment strategies.

Tau PET and relative cerebral blood flow in dementia with Lewy bodies: A PET study.

PURPOSE: Alpha-synuclein often co-occurs with Alzheimer's disease (AD) pathology in Dementia with Lewy Bodies (DLB). From a dynamic [18F]flortaucipir PET scan we derived measures of both tau binding and relative cerebral blood flow (rCBF). We tested whether regional tau binding or rCBF differed between DLB patients and AD patients and controls and examined their association with clinical characteristics of DLB. METHODS: Eighteen patients with probable DLB, 65 AD patients and 50 controls underwent a dynamic 130-minute [18F]flortaucipir PET scan. DLB patients with positive biomarkers for AD based on cerebrospinal fluid or amyloid PET were considered as DLB with AD pathology (DLB-AD+). Receptor parametric mapping (cerebellar gray matter reference region) was used to extract regional binding potential (BPND) and R1, reflecting (AD-specific) tau pathology and rCBF, respectively. First, we performed regional comparisons of [18F]flortaucipir BPND and R1 between diagnostic groups. In DLB patients only, we performed regression analyses between regional [18F]flortaucipir BPND, R1 and performance on ten neuropsychological tests. RESULTS: Regional [18F]flortaucipir BPND in DLB was comparable with tau binding in controls (p > 0.05). Subtle higher tau binding was observed in DLB-AD+ compared to DLB-AD- in the medial temporal and parietal lobe (both p < 0.05). Occipital and lateral parietal R1 was lower in DLB compared to AD and controls (all p < 0.01). Lower frontal R1 was associated with impaired performance on digit span forward (standardized beta, stß = 0.72) and category fluency (stß = 0.69) tests. Lower parietal R1 was related to lower delayed (stß = 0.50) and immediate (stß = 0.48) recall, VOSP number location (stß = 0.70) and fragmented letters (stß = 0.59) scores. Lower occipital R1 was associated to worse performance on VOSP fragmented letters (stß = 0.61), all p < 0.05. CONCLUSION: The amount of tau binding in DLB was minimal and did not differ from controls. However, there were DLB-specific occipital and lateral parietal relative cerebral blood flow reductions compared to both controls and AD patients. Regional rCBF, but not tau binding, was related to cognitive impairment. This indicates that assessment of rCBF may give more insight into disease mechanisms in DLB than tau PET.

Reviewing the role of the genes G72 and DAAO in glutamate neurotransmission in schizophrenia.

We review the role of two susceptibility genes; G72 and DAAO in glutamate neurotransmission and the aetiology of schizophrenia. The gene product of G72 is an activator of DAAO (D-amino acid oxidase), which is the only enzyme oxidising D-serine. D-serine is an important co-agonist for the NMDA glutamate receptor and plays a role in neuronal migration and cell death. Studies of D-serine revealed lower serum levels in schizophrenia patients as compared to healthy controls. Furthermore, administration of D-serine as add-on medication reduced the symptoms of schizophrenia. The underlying mechanism of the involvement of G72 and DAAO in schizophrenia is probably based on decreased levels of D-serine and decreased NMDA receptor functioning in patients. The involvement of this gene is therefore indirect support for the glutamate dysfunction hypothesis in schizophrenia.