Clinical value of cerebrospinal fluid neurofilament light chain in semantic dementia

BACKGROUND

Semantic dementia (SD) is a neurodegenerative disorder characterised by progressive language problems falling within the clinicopathological spectrum of frontotemporal lobar degeneration (FTLD). The development of disease-modifying agents may be facilitated by the relative clinical and pathological homogeneity of SD, but we need robust monitoring biomarkers to measure their efficacy. In different FTLD subtypes, neurofilament light chain (NfL) is a promising marker, therefore we investigated the utility of cerebrospinal fluid (CSF) NfL in SD.

METHODS

This large retrospective multicentre study compared cross-sectional CSF NfL levels of 162 patients with SD with 65 controls. CSF NfL levels of patients were correlated with clinical parameters (including survival), neuropsychological test scores and regional grey matter atrophy (including longitudinal data in a subset).

RESULTS

CSF NfL levels were significantly higher in patients with SD (median: 2326 pg/mL, IQR: 1628-3593) than in controls (577 (446-766), p<0.001). Higher CSF NfL levels were moderately associated with naming impairment as measured by the Boston Naming Test (rs =-0.32, p=0.002) and with smaller grey matter volume of the parahippocampal gyri (rs =-0.31, p=0.004). However, cross-sectional CSF NfL levels were not associated with progression of grey matter atrophy and did not predict survival.

CONCLUSION

CSF NfL is a promising biomarker in the diagnostic process of SD, although it has limited cross-sectional monitoring or prognostic abilities.

A nonsynonymous mutation in PLCG2 reduces the risk of Alzheimer's disease, dementia with Lewy bodies and frontotemporal dementia, and increases the likelihood of longevity

The genetic variant rs72824905-G (minor allele) in the PLCG2 gene was previously associated with a reduced Alzheimer's disease risk (AD). The role of PLCG2 in immune system signaling suggests it may also protect against other neurodegenerative diseases and possibly associates with longevity. We studied the effect of the rs72824905-G on seven neurodegenerative diseases and longevity, using 53,627 patients, 3,516 long-lived individuals and 149,290 study-matched controls. We replicated the association of rs72824905-G with reduced AD risk and we found an association with reduced risk of dementia with Lewy bodies (DLB) and frontotemporal dementia (FTD). We did not find evidence for an effect on Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS) risks, despite adequate sample sizes. Conversely, the rs72824905-G allele was associated with increased likelihood of longevity. By-proxy analyses in the UK Biobank supported the associations with both dementia and longevity. Concluding, rs72824905-G has a protective effect against multiple neurodegenerative diseases indicating shared aspects of disease etiology. Our findings merit studying the PLCγ2 pathway as drug-target.

Cerebrospinal Fluid Amyloid-β Subtypes in Confirmed Frontotemporal Lobar Degeneration Cases: A Pilot Study

To investigate amyloid-β (Aβ) in frontotemporal dementia (FTD), cerebrospinal fluid (CSF) Aβ38, Aβ40, and Aβ42 in frontotemporal lobar degeneration (FTLD; N = 18 genetically and/or pathologically confirmed and N = 8 FTD with concomitant amyotrophic lateral sclerosis) were compared with Alzheimer's disease (AD; pathological or Pittsburgh-compound-B Positron-emission-tomography (PIB-PET) positive; N = 25) and controls (N = 24). For all the Aβ subtypes, group difference was seen and post-hoc analysis revealed lower levels in FTLD compared to controls (p≤0.05). Aβ42/40 ratio showed no difference between FTLD and controls; however, a difference was seen between AD versus FTLD (p < 0.01). This is an intriguing finding, suggesting a possible role of Aβ in FTLD pathogenesis.

Von Economo neurons are part of a larger neuronal population that are selectively vulnerable in C9orf72 frontotemporal dementia

AIMS

The behavioural variant of frontotemporal dementia with a C9orf72 expansion (C9-bvFTD) is characterised by early changes in social-emotional cognition that are linked to the loss of von Economo neurons (VENs). Together with a subset of neighbouring pyramidal neurons, VENs express the GABA receptor subunit theta (GABRQ). It is not known if the selective vulnerability of VENs in C9-bvFTD also includes this GABRQ-expressing population.

METHODS

We quantified VENs and GABRQ immunopositive neurons in the anterior cingulate cortex (ACC) in C9-bvFTD (n = 16), controls (n = 12) and Alzheimer's disease (AD) (n = 7). Second, we assessed VENs and GABRQ-expressing populations in relation to the clinicopathological profiles.

RESULTS

We found the number of VENs and GABRQ-expressing neurons and their ratio over the total layer 5 neuronal population was lower in C9-bvFTD compared to control and AD. C9-bvFTD donors with underlying TDP43 type A pathology in the ACC showed the highest loss of GABRQ-expressing neurons. C9-bvFTD donors that did not present with motor neuron disease (MND) symptoms in the first half of their disease course showed a prominent loss of GABRQ-expressing neurons compared to controls. C9-bvFTD donors with no symptoms of psychosis showed a higher loss compared to controls. Across all donors, the number of VENs correlated strongly with the number of GABRQ-expressing neurons.

CONCLUSION

We show that VENs, together with GABRQ-expressing neurons, are selectively vulnerable in C9-bvFTD but are both spared in AD. This suggests they are related and that this GABRQ-expressing population of VENs and pyramidal neurons, is a key modulator of social-emotional functioning.

Single Subject Classification of Alzheimer's Disease and Behavioral Variant Frontotemporal Dementia Using Anatomical, Diffusion Tensor, and Resting-State Functional Magnetic Resonance Imaging

BACKGROUND/OBJECTIVE

Overlapping clinical symptoms often complicate differential diagnosis between patients with Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD). Magnetic resonance imaging (MRI) reveals disease specific structural and functional differences that aid in differentiating AD from bvFTD patients. However, the benefit of combining structural and functional connectivity measures to-on a subject-basis-differentiate these dementia-types is not yet known.

METHODS

Anatomical, diffusion tensor (DTI), and resting-state functional MRI (rs-fMRI) of 30 patients with early stage AD, 23 with bvFTD, and 35 control subjects were collected and used to calculate measures of structural and functional tissue status. All measures were used separately or selectively combined as predictors for training an elastic net regression classifier. Each classifier's ability to accurately distinguish dementia-types was quantified by calculating the area under the receiver operating characteristic curves (AUC).

RESULTS

Highest AUC values for AD and bvFTD discrimination were obtained when mean diffusivity, full correlations between rs-fMRI-derived independent components, and fractional anisotropy (FA) were combined (0.811). Similarly, combining gray matter density (GMD), FA, and rs-fMRI correlations resulted in highest AUC of 0.922 for control and bvFTD classifications. This, however, was not observed for control and AD differentiations. Classifications with GMD (0.940) and a GMD and DTI combination (0.941) resulted in similar AUC values (p = 0.41).

CONCLUSION

Combining functional and structural connectivity measures improve dementia-type differentiations and may contribute to more accurate and substantiated differential diagnosis of AD and bvFTD patients. Imaging protocols for differential diagnosis may benefit from also including DTI and rs-fMRI.

Early recognition and treatment of neuropsychiatric symptoms to improve quality of life in early Alzheimer's disease: protocol of the BEAT-IT study

BACKGROUND

Neuropsychiatric symptoms (NPS) are very common in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) dementia and are associated with various disadvantageous clinical outcomes including a negative impact on quality of life, caregiver burden, and accelerated disease progression. Despite growing evidence of the efficacy of (non)pharmacological interventions to reduce these symptoms, NPS remain underrecognized and undertreated in memory clinics. The BEhavioural symptoms in Alzheimer's disease Towards early Identification and Treatment (BEAT-IT) study is developed to (1) investigate the neurobiological etiology of NPS in AD and (2) study the effectiveness of the Describe, Investigate, Create, Evaluate (DICE) approach to structure and standardize the current care of NPS in AD. By means of the DICE method, we aim to improve the quality of life of AD patients with NPS and their caregivers who visit the memory clinic. This paper describes the protocol for the intervention study that incorporates the latter aim.

METHODS

We aim to enroll a total of 150 community-dwelling patients with MCI or AD and their caregivers in two waves. First, we will recruit a control group who will receive care as usual. Next, the second wave of participants will undergo the DICE method. This approach consists of the following steps: (1) describe the context in which NPS occur, (2) investigate the possible causes, (3) create and implement a treatment plan, and (4) evaluate whether these interventions are effective. Primary outcomes are the quality of life of patients and their caregivers. Secondary outcomes include NPS change, caregiver burden, caregivers' confidence managing NPS, psychotropic medication use, the experiences of patients and caregivers who underwent the DICE method, and the cost-effectiveness of the intervention.

CONCLUSIONS

This paper describes the protocol of an intervention study that is part of the BEAT-IT study and aims to improve current recognition and treatment of NPS in AD by structuring and standardizing the detection and treatment of NPS in AD using the DICE approach.

TRIAL REGISTRATION

The trial was registered on the Netherlands Trial Registry ( NTR7459 ); registered 6 September 2018.

Individual Prediction of Behavioral Variant Frontotemporal Dementia Development Using Multivariate Pattern Analysis of Magnetic Resonance Imaging Data

BACKGROUND

Patients with behavioral variant of frontotemporal dementia (bvFTD) initially may only show behavioral and/or cognitive symptoms that overlap with other neurological and psychiatric disorders. The diagnostic accuracy is dependent on progressive symptoms worsening and frontotemporal abnormalities on neuroimaging findings. Predictive biomarkers could facilitate the early detection of bvFTD.

OBJECTIVE

To determine the prognostic accuracy of clinical and structural MRI data using a support vector machine (SVM) classification to predict the 2-year clinical follow-up diagnosis in a group of patients presenting late-onset behavioral changes.

METHODS

Data from 73 patients were included and divided into probable/definite bvFTD (n = 18), neurological (n = 28), and psychiatric (n = 27) groups based on 2-year follow-up diagnosis. Grey-matter volumes were extracted from baseline structural MRI scans. SVM classifiers were used to perform three binary classifications: bvFTD versus neurological and psychiatric, bvFTD versus neurological, and bvFTD versus psychiatric group(s), and one multi-class classification. Classification performance was determined for clinical and neuroimaging data separately and their combination using 5-fold cross-validation.

RESULTS

Accuracy of the binary classification tasks ranged from 72-82% (p < 0.001) with adequate sensitivity (67-79%), specificity (77-88%), and area-under-the-receiver-operator-curve (0.80-0.9). Multi-class accuracy ranged between 55-59% (p < 0.001). The combination of clinical and voxel-wise whole brain data showed the best performance overall.

CONCLUSION

These results show the potential for automated early confirmation of diagnosis for bvFTD using machine learning analysis of clinical and neuroimaging data in a diverse and clinically relevant sample of patients.

Novel CSF biomarkers in genetic frontotemporal dementia identified by proteomics

Objective

To identify novel CSF biomarkers in GRN‐associated frontotemporal dementia (FTD) by proteomics using mass spectrometry (MS).

Methods

Unbiased MS was applied to CSF samples from 19 presymptomatic and 9 symptomatic GRN mutation carriers and 24 noncarriers. Protein abundances were compared between these groups. Proteins were then selected for validation if identified by ≥4 peptides and if fold change was ≤0.5 or ≥2.0. Validation and absolute quantification by parallel reaction monitoring (PRM), a high‐resolution targeted MS method, was performed on an international cohort (n = 210) of presymptomatic and symptomatic GRN, C9orf72 and MAPT mutation carriers.

Results

Unbiased MS revealed 20 differentially abundant proteins between symptomatic mutation carriers and noncarriers and nine between symptomatic and presymptomatic carriers. Seven of these proteins fulfilled our criteria for validation. PRM analyses revealed that symptomatic GRN mutation carriers had significantly lower levels of neuronal pentraxin receptor (NPTXR), receptor‐type tyrosine‐protein phosphatase N2 (PTPRN2), neurosecretory protein VGF, chromogranin‐A (CHGA), and V‐set and transmembrane domain‐containing protein 2B (VSTM2B) than presymptomatic carriers and noncarriers. Symptomatic C9orf72 mutation carriers had lower levels of NPTXR, PTPRN2, CHGA, and VSTM2B than noncarriers, while symptomatic MAPT mutation carriers had lower levels of NPTXR and CHGA than noncarriers.

Interpretation

We identified and validated five novel CSF biomarkers in GRN‐associated FTD. Our results show that synaptic, secretory vesicle, and inflammatory proteins are dysregulated in the symptomatic stage and may provide new insights into the pathophysiology of genetic FTD. Further validation is needed to investigate their clinical applicability as diagnostic or monitoring biomarkers.

The cognitive profile of behavioural variant FTD and its similarities with ALS: a systematic review and meta-analysis

Approximately 30% of patients with amyotrophic lateral sclerosis (ALS) have cognitive impairment and 8%-14% fulfil the criteria for behavioural variant frontotemporal dementia (bv-FTD). The cognitive profiles of ALS and bv-FTD have been reported to be comparable, but this has never been systematically investigated. We aimed to determine the cognitive profile of bv-FTD and examine its similarities with that of ALS, to provide evidence for the existence of a cognitive disease continuum encompassing bv-FTD and ALS. We therefore systematically reviewed neuropsychological studies on bv-FTD patients and healthy volunteers. Neuropsychological tests were divided in 10 cognitive domains and effect sizes were calculated for all domains and compared with the cognitive profile of ALS by means of a visual comparison and a Pearson's r correlation coefficient. We included 120 studies, totalling 2425 bv-FTD patients and 2798 healthy controls. All cognitive domains showed substantial effect sizes, indicating cognitive impairment in bv-FTD patients compared to healthy controls. The cognitive domains with the largest effect sizes were social cognition, verbal memory and fluency (1.77-1.53). The cognitive profiles of bv-FTD and ALS (10 cognitive domains, 1287 patients) showed similarities on visual comparison and a moderate correlation 0.58 (p=0.13). When social cognition, verbal memory, fluency, executive functions, language and visuoperception were considered, i.e. the cognitive profile of ALS, Pearson's r was 0.73 (p=0.09), which raised to 0.92 (p=0.03), when language was excluded in this systematic analysis of patients with a non-language subtype of FTD. The cognitive profile of bv-FTD consists of deficits in social cognition, verbal memory, fluency and executive functions and shows similarities with the cognitive profile of ALS. These findings support a cognitive continuum encompassing ALS and bv-FTD.

[Behavioural changes as a symptom: diagnosing behavioural variant frontotemporal dementia]

Behavioural variant frontotemporal dementia (bvFTD) is a neurodegenerative disease, the symptoms of which are changes in character, behavioural changes and socio-cognitive changes occurring predominantly at an age between 40 and 70 years. Frontotemporal atrophy is apparent on diagnostic imaging in 70% of patients with bvFTD; a diagnostic dilemma arises if this is not clearly obvious. Validated questionnaires for stereotypical behaviour, depressive symptoms and apathy, and neuropsychological examination can be very helpful in differentiating between bvFTD and psychiatric and other neurological conditions. A brain MRI is always indicated in patients displaying behavioural changes; frontal or temporal atrophy on brain MRI provide sufficient support for the diagnosis 'probable bvFTD'. When in doubt, a supplementary 18F-FDG-PET scan can be performed, but hypometabolism on an 18F-FDG-PET scan can give a false-positive result. If bvFTD is suspected, a multidisciplinary approach, clinical follow-up for 2 years and referral to an FTD centre of excellence are recommended. Conflict of interest and financial support: none declared.

Hypometabolism of the posterior cingulate cortex is not restricted to Alzheimer's disease

When differential diagnosis of dementia includes both Alzheimer's disease (AD) and the behavioural variant of frontotemporal dementia (bvFTD), distribution of cerebral glucose metabolism as measured using [¹⁸F]‑2‑fluoro‑2‑deoxy‑d‑glucose positron emission tomography ([¹⁸F]FDG-PET) may be helpful. One important clue for differentiation is the presence of hypometabolism in the posterior cingulate cortex (PCC), usually associated with AD. PCC hypometabolism however, could also be present in bvFTD. Therefore, the specificity of PCC hypometabolism was examined. Based on visual reading PCC hypometabolism was present in 69–73/81 probable AD patients, in 10–16/33 probable bvFTD patients, and in 0–1/22 cognitive normal (CN) subjects. Findings were validated using a PCC to reference tissue [¹⁸F]FDG standard uptake value ratio (SUVr) cut-off, which was derived from the receiver operating characteristic (ROC) separating probable AD from CN, resulting in 9–14/33 bvFTD patients having PCC hypometabolism, depending on the reference tissue used. In conclusion, PCC hypometabolism is not restricted to AD.

Poly(GP), neurofilament and grey matter deficits in C9orf72 expansion carriers

Objective

To evaluate poly(GP), a dipeptide repeat protein, and neurofilament light chain (NfL) as biomarkers in presymptomatic C9orf72 repeat expansion carriers and patients with C9orf72‐associated frontotemporal dementia. Additionally, to investigate the relationship of poly(GP) with indicators of neurodegeneration as measured by NfL and grey matter volume.

Methods

We measured poly(GP) and NfL levels in cerebrospinal fluid (CSF) from 25 presymptomatic C9orf72 expansion carriers, 64 symptomatic expansion carriers with dementia, and 12 noncarriers. We explored associations with grey matter volumes using region of interest and voxel‐wise analyses.

Results

Poly(GP) was present in C9orf72 expansion carriers and absent in noncarriers (specificity 100%, sensitivity 97%). Presymptomatic carriers had lower poly(GP) levels than symptomatic carriers. NfL levels were higher in symptomatic carriers than in presymptomatic carriers and healthy noncarriers. NfL was highest in patients with concomitant motor neuron disease, and correlated with disease severity and survival. Associations between poly(GP) levels and small grey matter regions emerged but did not survive multiple comparison correction, while higher NfL levels were associated with atrophy in frontotemporoparietal cortices and the thalamus.

Interpretation

This study of C9orf72 expansion carriers reveals that: (1) poly(GP) levels discriminate presymptomatic and symptomatic expansion carriers from noncarriers, but are not associated with indicators of neurodegeneration; and (2) NfL levels are associated with grey matter atrophy, disease severity, and shorter survival. Together, poly(GP) and NfL show promise as complementary biomarkers for clinical trials for C9orf72‐associated frontotemporal dementia, with poly(GP) as a potential marker for target engagement and NfL as a marker of disease activity and progression.

Clinical value of neurofilament and phospho-tau/tau ratio in the frontotemporal dementia spectrum

Objective

To examine the clinical value of neurofilament light chain (NfL) and the phospho-tau/total tau ratio (p/t-tau) across the entire frontotemporal dementia (FTD) spectrum in a large, well-defined cohort.

Methods

CSF NfL and p/t-tau levels were studied in 361 patients with FTD: 179 behavioral variant FTD, 17 FTD with motor neuron disease (FTD-MND), 36 semantic variant primary progressive aphasia (PPA), 19 nonfluent variant PPA, 4 logopenic variant PPA (lvPPA), 42 corticobasal syndrome, and 64 progressive supranuclear palsy. Forty-five cognitively healthy controls were also included. Definite pathology was known in 68 patients (49 frontotemporal lobar degeneration [FTLD]-TDP, 18 FTLD-tau, 1 FTLD-FUS).

Results

NfL was higher in all diagnoses, except lvPPA (n = 4), than in controls, equally elevated in behavioral variant FTD, semantic variant PPA, nonfluent variant PPA, and corticobasal syndrome, and highest in FTD-MND. The p/t-tau was lower in all clinical groups, except lvPPA, than in controls and lowest in FTD-MND. NfL did not discriminate between TDP and tau pathology, while the p/t-tau ratio had a good specificity (76%) and moderate sensitivity (67%). Both high NfL and low p/t-tau were associated with poor survival (hazard ratio on tertiles 1.7 for NfL, 0.7 for p/t-tau).

Conclusion

NfL and p/t-tau similarly discriminated FTD from controls, but not between clinical subtypes, apart from FTD-MND. Both markers predicted survival and are promising monitoring biomarkers for clinical trials. Of note, p/t-tau, but not NfL, was specific to discriminate TDP from tau pathology in vivo.

Classification of evidence

This study provides Class III evidence that for patients with cognitive issues, CSF NfL and p/t-tau levels discriminate between those with and without FTD spectrum disorders.

A Longitudinal Study on Resting State Functional Connectivity in Behavioral Variant Frontotemporal Dementia and Alzheimer's Disease

BACKGROUND/OBJECTIVE

Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) are the most common types of early-onset dementia. We applied longitudinal resting state functional magnetic resonance imaging (fMRI) to delineate functional brain connections relevant for disease progression and diagnostic accuracy.

METHODS

We used two-center resting state fMRI data of 20 AD patients (65.1±8.0 years), 12 bvFTD patients (64.7±5.4 years), and 22 control subjects (63.8±5.0 years) at baseline and 1.8-year follow-up. We used whole-network and voxel-based network-to-region analyses to study group differences in functional connectivity at baseline and follow-up, and longitudinal changes in connectivity within and between groups.

RESULTS

At baseline, connectivity between paracingulate gyrus and executive control network, between cuneal cortex and medial visual network, and between paracingulate gyrus and salience network was higher in AD compared with controls. These differences were also present after 1.8 years. At follow-up, connectivity between angular gyrus and right frontoparietal network, and between paracingulate gyrus and default mode network was lower in bvFTD compared with controls, and lower compared with AD between anterior cingulate gyrus and executive control network, and between lateral occipital cortex and medial visual network. Over time, connectivity decreased in AD between precuneus and right frontoparietal network and in bvFTD between inferior frontal gyrus and left frontoparietal network. Longitudinal changes in connectivity between supramarginal gyrus and right frontoparietal network differ between both patient groups and controls.

CONCLUSION

We found disease-specific brain regions with longitudinal connectivity changes. This suggests the potential of longitudinal resting state fMRI to delineate regions relevant for disease progression and for diagnostic accuracy, although no group differences in longitudinal changes in the direct comparison of AD and bvFTD were found.

Tau Rather than TDP-43 Proteins are Potential Cerebrospinal Fluid Biomarkers for Frontotemporal Lobar Degeneration Subtypes: A Pilot Study

BACKGROUND

Frontotemporal dementia (FTD) is a heterogeneous disease both at the clinical, genetic, and pathobiological level. The underlying pathological spectrum (termed FTLD, frontotemporal lobar degeneration) is in most cases defined by accumulation of either tau (FTLD-tau) or TDP-43 proteins (FTLD-TDP). Biomarkers to differentiate these subtypes are not yet available, whereas these are essential requirements to study the natural course of disease and for homogeneous inclusion of patients in clinical studies.

OBJECTIVE

To study if a combination of total (t-) and phosphorylated (p-)tau, and t-TDP-43 and p-TDP-43 proteins in cerebrospinal fluid (CSF) is suitable to discriminate FTLD-tau and FTLD-TDP subtypes.

METHODS

We developed immunoassays for the quantification of t-TDP-43 and p-TDP-43 proteins and used commercially available assays for the quantification of t-tau and p-tau proteins. We quantified these proteins in ventricular CSF samples from neuropathologically defined FTLD-tau and FTLD-TDP cases to study the reflection of underlying brain pathology in CSF composition, and in lumbar CSF samples from FTLD-tau and FTLD-TDP patients to study the diagnostic potential of CSF biomarkers.

RESULTS

In ventricular CSF, t-TDP-43 and t-tau levels, when combined into one model, were significantly different between neuropathologically-defined FTLD-tau and FTLD-TDP cases. In a pilot study using lumbar CSF, the p-tau/t-tau ratio, but not t-TDP-43 levels, were significantly different between FTLD-TDP and FTLD-tau patients.

CONCLUSION

We conclude that with current available methods, CSF tau, rather than TDP-43 proteins, may have diagnostic value in the differentiation of FTLD patients with either tau or TDP-43 pathology.

Rare Genetic Variant in SORL1 May Increase Penetrance of Alzheimer's Disease in a Family with Several Generations of APOE-ɛ4 Homozygosity

Background: The major genetic risk factor for late onset Alzheimer’s disease (AD) is the APOE-ɛ4 allele. However, APOE-ɛ4 homozygosity is not fully penetrant, suggesting co-occurrence of additional genetic variants.

Objective: To identify genetic factors that, next to APOE-ɛ4 homozygosity, contribute to the development of AD.

Methods: We identified a family with nine AD patients spanning four generations, with an inheritance pattern suggestive of autosomal dominant AD, with no variants in PSEN1, PSEN2, or APP. We collected DNA from four affected and seven unaffected family members and performed exome sequencing on DNA from three affected and one unaffected family members.

Results: All affected family members were homozygous for the APOE-ɛ4 allele. Statistical analysis revealed that AD onset in this family was significantly earlier than could be expected based on APOE genotype and gender. Next to APOE-ɛ4 homozygosity, we found that all four affected family members carried a rare variant in the VPS10 domain of the SORL1 gene, associated with AβPP processing and AD risk. Furthermore, three of four affected family members carried a rare variant in the TSHZ3 gene, also associated with AβPP processing. Affected family members presented between 61 and 74 years, with variable presence of microbleeds/cerebral amyloid angiopathy and electroencephalographic abnormalities.

Conclusion: We hypothesize that next to APOE-ɛ4 homozygosity, impaired SORL1 protein function, and possibly impaired TSHZ3 function, further disturbed Aβ processing. The convergence of these genetic factors over several generations might clarify the increased AD penetrance and the autosomal dominant-like inheritance pattern of AD as observed in this family.

Diagnostic Accuracy of the Frontotemporal Dementia Consensus Criteria in the Late-Onset Frontal Lobe Syndrome

BACKGROUND/AIMS

We aimed to prospectively assess the diagnostic accuracy of the revised criteria for behavioural variant frontotemporal dementia (bvFTD) among subjects presenting with a frontal lobe syndrome in middle-late adulthood.

METHODS

Patients were included based on a predominant behavioural clinical presentation, a Frontal Behavioural Inventory (FBI) score of ≥11 and/or a Stereotypy Rating Inventory (SRI) score of ≥10. At baseline, the fulfilment of the international consensus criteria for behavioural variant FTD (FTDC) was systematically recorded. The 2-year follow-up consensus diagnosis was used as the gold standard to calculate sensitivity and specificity of the FTDC criteria for possible and probable bvFTD.

RESULTS

Two-year follow-up data were available for 116 patients (85%). Two-year follow-up consensus diagnoses consisted of probable/definite bvFTD (n = 27), other dementia (n = 30), psychiatric disorders (n = 46) and other neurological disorders (n = 13). Sensitivity for possible bvFTD was 85% (95% CI 70-95%) at a specificity of 27% (95% CI 19-37%). Sensitivity for probable bvFTD was 85% (95% CI 69-95%), whereas their specificity was 82% (95% CI 73-89%).

CONCLUSIONS

We found a good diagnostic accuracy for FTDC probable bvFTD. However, the specificity for FTDC possible bvFTD was low. Our results reflect the symptomatic overlap between bvFTD, other neurological conditions and psychiatric disorders, and the relevance of adding neuroimaging to the diagnostic process.

Gait Speed and Grip Strength Reflect Cognitive Impairment and Are Modestly Related to Incident Cognitive Decline in Memory Clinic Patients With Subjective Cognitive Decline and Mild Cognitive Impairment: Findings From the 4C Study

Background

Prospective studies in the general population show that slow gait speed is associated with cognitive decline and clinical progression to dementia. However, longitudinal studies in memory clinic populations are mostly lacking. We aimed to study the association between gait speed and grip strength and cognitive functioning at baseline and cognitive decline over time in memory clinic patients with subjective cognitive decline and mild cognitive impairment.

Methods

We included 309 patients (age 70 ± 9 years, 108 [35%] women, Mini-Mental State Examination 27 ± 3 points). Baseline gait speed was assessed over 15 feet, grip strength with a hydraulic hand dynamometer. Cognitive functioning was assessed annually with a comprehensive test battery during 3 years.

Results

Age- and gender-adjusted linear mixed models showed that slower gait speed was related to worse baseline attention, memory, information processing speed, and verbal fluency. Longitudinally, gait speed was related to decline in information processing speed and executive functioning. Weaker grip strength was related to worse baseline information processing speed and executive functioning but there were no longitudinal associations. Cox proportional hazards models revealed no significant associations with clinical progression.

Conclusions

Our findings suggest that markers of physical performance are related to current cognitive status and modestly related to cognitive decline but are seemingly not useful as an early marker of incident clinical progression.

A novel CCM2 variant in a family with non-progressive cognitive complaints and cerebral microbleeds

Lobar cerebral microbleeds are most often sporadic and associated with Alzheimer's disease. The aim of our study was to identify the underlying genetic defect in a family with cognitive complaints and multiple lobar microbleeds and a positive family history for early onset Alzheimer's disease. We performed exome sequencing followed by Sanger sequencing for validation purposes on genomic DNA of three siblings with cognitive complaints, reduced amyloid-beta-42 in CSF and multiple cerebral lobar microbleeds. We checked for the occurrence of the variant in a cohort of 363 patients with early onset dementia and/or microbleeds. A novel frameshift variant (c.236_237delAC) generating a premature stop codon in the CCM2 gene shared by all three siblings was identified. Pathogenicity of the variant was supported by the presence of cerebral cavernous malformations in two of the siblings and by the absence of the variant exome variant databases. Two siblings were homozygous for APOE-ϵ4; one heterozygous. The cognitive complaints, reduced amyloid-beta-42 in CSF and microbleeds suggest preclinical Alzheimer's disease, but the stability of the cognitive complaints does not. We hypothesize that the phenotype in this family may be due to a combination of the CCM2 variant and the APOE status. © 2016 The Authors. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics Published by Wiley Periodicals, Inc.

Cerebrospinal fluid biomarker examination as a tool to discriminate behavioral variant frontotemporal dementia from primary psychiatric disorders

INTRODUCTION

To prospectively determine the diagnostic value of cerebrospinal fluid (CSF) levels total-tau (tau) to amyloid-β_1-42 ratio (Aβ_1-42) ratio (tau/Aβ_1-42 ratio), phosphorylated-tau (p-tau) to tau ratio (p-tau/tau ratio), neurofilament light chain (NfL) and YKL40 in the late-onset frontal lobe syndrome, in particular for the differential diagnosis of behavioral variant frontotemporal dementia (bvFTD) versus primary psychiatric disorders (PSY).

METHOD

We included patients with a multidisciplinary 2-year-follow-up diagnosis of probable/definite bvFTD (n = 22) or PSY (n = 25), who underwent a detailed neuropsychiatric clinical examination, neuropsychological test battery, and magnetic resonance imaging at baseline. In all cases, CSF was collected through lumbar puncture at baseline. We compared CSF biomarker levels between the two groups and measured the diagnostic accuracy for probable/definite bvFTD, using the follow-up diagnosis as the reference standard.

RESULTS

The best discriminators between probable/definite bvFTD and PSY were the levels of CSF NfL (area under the curve [AUC] 0.93, P < .001, 95% confidence interval [CI] 0.85-1.00), p-tau/tau ratio (AUC 0.87, P < .001, 95% CI 0.77-0.97), and YKL40 (AUC 0.82, P = .001, 95% CI 0.68-0.97). The combination of these three biomarkers had a sensitivity of 91% (95% CI 66%-100%) at a specificity of 83% (95% CI 65%-95%) with an AUC of 0.94 (P < .001, 95% CI 0.87-1.00) for bvFTD. CSF tau/Aβ_1-42 ratio was less accurate in differentiating between bvFTD and PSY.

DISCUSSION

We found a good diagnostic accuracy for higher levels of CSF NfL and YKL40 and reduced p-tau/tau ratio in distinguishing bvFTD from PSY. We advocate the use of these CSF biomarkers as potential additional tools to neuroimaging in the diagnosis of bvFTD versus PSY.

Stability of Progranulin Under Pre-Analytical Conditions in Serum and Cerebrospinal Fluid

Progranulin (PGRN) levels in blood and cerebrospinal fluid (CSF) are increasingly studied as potential markers for neurodegenerative disorders. We aimed to 1) characterize two commercially available PGRN ELISAs on several assay validation parameters, 2) assess the stability of PGRN in serum and CSF under pre-analytical conditions, and 3) compare stability in the two assays. Intra- and inter-assay variation, inter-lot variation, linearity, lower limit of detection, and kit correlations were assessed for the Adipogen and R&D PGRN ELISA kits. Blood and serum samples were experimentally exposed to ≤9 freeze/thaw cycles, delayed processing for ≤24 h at room temperature and 4°C, and to temperature stability tests for ≤3 weeks at -20°C, 4°C, room temperature, and 37°C. Both commercial PGRN ELISA kits showed acceptable ranges for intra- and inter-assay variation, where the R&D kit performed more accurate than the Adipogen kit, especially for inter-assay variation (intra-assay serum: 6.7 and 8.3%, respectively; inter-assay serum: 9.2 and 21.0%; intra-assay CSF: 3.6 and 12.0%; inter-assay CSF: 16.0 and 44.5%). Absolute serum PGRN concentrations were 1.9-fold higher in Adipogen than R&D (p < 0.001) and strongly correlated between both kits (ρ= 0.86, p < 0.0001) and CSF PGRN levels were on the borderline of detection in both kits. PGRN was typically stable under all pre-analytical conditions addressed, although two weeks at 37°C resulted in decreased PGRN concentrations in CSF, only when using the Adipogen kit. These results support further examination of PGRN as a potential marker in neurodegenerative diseases, since PGRN is stable in serum and CSF and can be measured using ELISA kits from several providers.

[DNA diagnostics in dementia]

- Thanks to next-generation sequencing several genes can be examined in one go. Since this method has been introduced, the possibilities for DNA diagnostics in patients with dementia have increased tremendously in recent years.- DNA diagnostics is indicated for patients with an Alzheimer's disease diagnosis before they are 60 years old, for all patients with frontotemporal dementia and for patients with a positive family history.- For 15% of the patients who visited the Alzheimer centre of the VUmc, in Amsterdam, the Netherlands DNA diagnostics indicated a clear monogenic cause.- Although a hereditary cause of dementia is often a hard message for patients and their families, this knowledge often provides them with more clarity with respect to the diagnosis and the course of the disease. In addition, family members may choose to carry out presymptomatic DNA testing.- The therapeutical consequences of DNA diagnostics are currently minimal; several studies are being carried out internationally in this area.

[Chronic traumatic encephalopathy: an old acquaintance in athletes]

- Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease caused by repetitive head injuries like those seen in sports such as boxing, American football and soccer.- The clinical features of CTE are a range of cognitive, psychiatric and motor symptoms, and histopathology involves deposits of hyperphosphorylated tau protein and the presence of TAR DNA-binding protein (TDP-43) with relatively little beta-amyloid.- CTE is difficult to differentiate clinically from Alzheimer's disease, frontotemporal dementia and psychiatric disorders because of the major symptom overlap between these conditions.- The most important risk factors for developing CTE are the cumulative effect of repetitive head injuries, with or without clinical symptoms, and the duration of exposure to the repetitive injuries (the sporting career).- There is no treatment for CTE at present and the strategy must be primarily geared to prevention.- In view of the large number of people, including those in the Netherlands, who take part in sports in which head injuries may occur, research into CTE is of major societal importance.