Grey matter atrophy in patients with benign multiple sclerosis

BACKGROUND

Brain atrophy appears during the progression of multiple sclerosis (MS) and is associated with the disability caused by the disease.

METHODS

We investigated global and regional grey matter (GM) and white matter (WM) volumes, WM lesion load, and corpus callosum index (CCI), in benign relapsing-remitting MS (BRRMS, n = 35) with and without any treatment and compared those to aggressive relapsing-remitting MS (ARRMS, n = 46). Structures were analyzed by using an automated MRI quantification tool (cNeuro®).

RESULTS

The total brain and cerebral WM volumes were larger in BRRMS than in ARRMS (p = .014, p = .017 respectively). In BRRMS, total brain volumes, regional GM volumes, and CCI were found similar whether or not disease-modifying treatment (DMT) was used. The total (p = .033), as well as subcortical (p = .046) and deep WM (p = .041) lesion load volumes were larger in BRRMS patients without DMT. Cortical GM volumes did not differ between BRRMS and ARRMS, but the volumes of total brain tissue (p = .014) and thalami (p = .003) were larger in patients with BRRMS compared to ARRMS. A positive correlation was found between CCI and whole-brain volume in both BRRMS (r = .73, p < .001) and ARRMS (r = .80, p < .01).

CONCLUSIONS

Thalamic volume is the most prominent measure to differentiate BRRMS and ARRMS. Validation of automated quantification of CCI provides an additional applicable MRI biomarker to detect brain atrophy in MS.

Brainstem atrophy is linked to extrapyramidal symptoms in frontotemporal dementia

Extrapyramidal (EP) symptoms are a known feature in a subpopulation of patients with behavioral variant frontotemporal dementia (bvFTD). Concomitant EP symptoms with FTD-like neuropsychiatric symptoms are also core features in progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). This complicates the early diagnosis of these disorders. Our retrospective register study aimed to discover imaging (MRI and FDG-PET) biomarkers to differentiate PSP, CBD, and bvFTD patients with extrapyramidal symptoms (EP +) from bvFTD patients without EP symptoms (EP-). The records of 2751 patients were screened for the diagnoses and presence of EP symptoms. A total of 222 patients were submitted to imaging analysis and applicable imaging data were recovered from 139 patients. Neuroimaging data were analyzed using Freesurfer software. In the whole cohort, EP + patients showed lower volumes of gray matter compared to EP- patients in the putamen (p = 0.002), bilateral globus pallidum (p = 0.002, p = 0.042), ventral diencephalon (p = 0.002) and brain stem (p < 0.001). In the bvFTD subgroup, there was volumetric difference between EP + and EP− patients in the brain stem. FDG-PET scans in the bvFTD patient subgroup showed that EP + patients had comparative hypometabolism of the superior cerebellar peduncle (SCP) and the frontal lobes. We discovered that EP symptoms are linked to brainstem atrophy in bvFTD patients and the whole cohort. Also, evident hypometabolism in the SCP of bvFTD EP + patients was detected as compared to bvFTD EP− patients. This could indicate that the EP symptoms in these diseases have a more caudal origin in the brainstem than in Parkinson’s disease.

GFAP as a biomarker in frontotemporal dementia and primary psychiatric disorders: diagnostic and prognostic performance

BACKGROUND

Frontotemporal lobar degeneration (FTLD) and primary psychiatric disorders (PPD) are characterised by overlapping clinical features but different aetiologies. Here, we assessed for the first time the potential of blood glial fibrillar acidic protein (GFAP), marker of astrogliosis, as a discriminative and prognostic tool in FTLD and PPD.

METHODS

The levels of GFAP in serum (sGFAP) of patients with FTLD (N=107) and PPD (N=44) and GFAP in whole blood samples (bGFAP) from FTLD (N=10), PPD (N=10) and healthy controls (N=18) were measured. We evaluated whether the sGFAP levels associate with C9orf72 repeat expansion, survival of FTLD and PPD patients, and brain atrophy assessed cross-sectionally and longitudinally by structural T1W MRI. We also examined the correlation between sGFAP and bGFAP levels in a subset of patients.

RESULTS

sGFAP and bGFAP levels were elevated in the FTLD group compared with the PPD or control groups. Receiver operating characteristic analysis indicated an excellent diagnostic performance between FTLD and PPD (the area under the curve (AUC)=0.820, 95% CI 0.745 to 0.896). sGFAP and bGFAP levels showed a strong correlation and elevated sGFAP levels significantly associated with atrophy rate in the temporal cortex and predicted shorter survival time in patients with FTLD. No association with C9orf72 repeat expansion was detected.

CONCLUSIONS

sGFAP enabled differentiation of patients with FTLD and PPD and associated with shorter survival and more severe brain atrophy rate in patients with FTLD. These results suggest that blood-based GFAP represents a minimally invasive and useful biomarker in the differential diagnostics between patients with FTLD and PPD and in evaluating disease progression and astrogliosis in FTLD.

Comparison of Prodromal Symptoms of Patients with Behavioral Variant Frontotemporal Dementia and Alzheimer Disease

INTRODUCTION

Behavioral variant frontotemporal dementia (bvFTD) is the most common clinical subtype of frontotemporal lobar degeneration. bvFTD is often characterized by changes in behavior and personality, frequently leading to psychiatric misdiagnoses. On the other hand, substantial clinical overlap with other neurodegenerative diseases, such as Alzheimer disease (AD), further complicates the diagnostics.

OBJECTIVE

Our aim was to identify the main differences in early symptoms of bvFTD and AD in the prodromal stages of the diseases. In addition, patients with bvFTD were analyzed separately according to whether they carry the C9orf72repeat expansion or not.

METHODS

Patient records of bvFTD (n = 75) and AD (n = 83) patients were analyzed retrospectively for memory and neuropsychiatric symptoms, sleeping disorders, and somatic complaints before the setting of the accurate diagnosis.

RESULTS

A total of 84% of bvFTD patients (n = 63) and 98.8% of AD patients (n = 82) reported subjective memory disturbances in the prodromal phases of the disease. bvFTD patients presented significantly more often with sleeping disorders, headache, inexplicable collapses, transient loss of consciousness, somatization, delusions, and hallucinations, suicidality, changes in oral behaviors, and urinary problems. In addition, poor financial judgement was frequently detected in patients with prodromal bvFTD. Aberrant sensations in the nose and throat without any physical explanation, regarded as somatizations, emerged only in bvFTD patients with the C9orf72 repeat expansion.

CONCLUSIONS

Subjective reporting of impaired episodic memory is a poor indicator in differentiating bvFTD from AD. Sleeping disturbances, delusions, hallucinations, and unexplained somatic complaints in a patient with cognitive disturbances should prompt the clinicians to consider bvFTD as a possible diagnostic option behind these symptoms. The spectrum of symptoms in the prodromal stages of bvFTD may be more diverse than the latest criteria suggest.

Serum neurofilament light chain in FTLD: association with C9orf72, clinical phenotype, and prognosis

Objective

The aim of the present study was to compare the levels of serum neurofilament light chain (sNfL) in frontotemporal lobar degeneration (FTLD) patients of different clinical subtypes (bvFTD, PPA, and FTLD‐MND) and with or without the C9orf72 repeat expansion, and to correlate sNfL levels to disease progression, assessed by the brain atrophy rate and survival time.

Methods

The sNfL levels were determined from 78 FTLD patients (C9orf72 repeat expansion carriers [n = 26] and non‐carriers [n = 52]) with Single Molecule Array (SIMOA). The progression of brain atrophy was evaluated using repeated T1‐weighted MRI scans and the survival time from medical records.

Results

In the total FTLD cohort, sNfL levels were significantly higher in C9orf72 repeat expansion carriers compared to non‐carriers. Considering clinical phenotypes, sNfL levels were higher in the C9orf72 repeat expansion carriers than in the non‐carriers in bvFTD and PPA groups. Furthermore, sNfL levels were the highest in the FTLD‐MND group (median 105 pg/mL) and the lowest in the bvFTD group (median 27 pg/mL). Higher sNfL levels significantly correlated with frontal cortical atrophy rate and subcortical grey matter atrophy rate. The higher sNfL levels also associated with shorter survival time.

Interpretation

Our results indicate that the C9orf72 repeat expansion carriers show elevated sNFL levels compared to non‐carriers and that the levels differ among different clinical phenotypes of FTLD. Higher sNfL levels correlated with a shorter survival time and cortical and subcortical atrophy rates. Thus, sNfL could prove as a potential prognostic biomarker in FTLD.

Serum neurofilament light chain is a discriminative biomarker between frontotemporal lobar degeneration and primary psychiatric disorders

Due to the significant clinical overlap between frontotemporal lobar degeneration (FTLD) spectrum disorders and late-onset primary psychiatric disorders (PPD), diagnostic biomarkers reflecting the different underlying pathophysiologies are urgently needed. Thus far, elevated cerebrospinal fluid (CSF) levels of neurofilament light chain (NfL) have been reported in various neurological conditions. Furthermore, recent advancements in ultrasensitive analytical methods (e.g., single molecule array, Simoa) have enabled sensitive and less invasive NfL detection also from blood samples. In this study, we evaluated the potential of serum NfL (sNfL) as a diagnostic tool between FTLD and PPD. We analyzed sNfL levels with Simoa from 125 participants including patients from FTLD (n = 91) and PPD (n = 34) spectra. Our results show that sNfL levels are higher in the FTLD group compared to the PPD group as well as in separate clinical subtypes of FTLD compared to different psychiatric manifestations (i.e., mood or psychotic disorders). At single-subject level, discrimination between FTLD and PPD was possible with 80% sensitivity and 85% specificity (AUC = 0.850, 95% CI 0.776–0.923), and between behavioral variant frontotemporal dementia (bvFTD) and PPD with 79% sensitivity and 85% specificity (AUC = 0.830, 95% CI 0.732–0.908). These findings highlight the potential of sNfL as a discriminating biomarker for FTLD over PPD in patients with wide-ranging behavioral, psychiatric and cognitive symptoms.

The Association Between Distinct Frontal Brain Volumes and Behavioral Symptoms in Mild Cognitive Impairment, Alzheimer's Disease, and Frontotemporal Dementia

Our aim was to investigate the association between behavioral symptoms of agitation, disinhibition, irritability, elation, and aberrant motor behavior to frontal brain volumes in a cohort with various neurodegenerative diseases. A total of 121 patients with mild cognitive impairment (MCI, n = 58), Alzheimer's disease (AD, n = 45) and behavioral variant frontotemporal dementia (bvFTD, n = 18) were evaluated with a Neuropsychiatric Inventory (NPI). A T1-weighted MRI scan was acquired for each participant and quantified with a multi-atlas segmentation method. The volumetric MRI measures of the frontal lobes were associated with neuropsychiatric symptom scores with a linear model. In the regression model, we included CDR score and TMT B time as covariates to account for cognitive and executive functions. The brain volumes were corrected for age, gender and head size. The total behavioral symptom score of the five symptoms of interest was negatively associated with the volume of the subcallosal area (β = −0.32, p = 0.002). High disinhibition scores were associated with reduced volume in the gyrus rectus (β = −0.30, p = 0.002), medial frontal cortex (β = −0.30, p = 0.002), superior frontal gyrus (β = −0.28, p = 0.003), inferior frontal gyrus (β = −0.28, p = 0.005) and subcallosal area (β = −0.28, p = 0.005). Elation scores were associated with reduced volumes of the medial orbital gyrus (β = −0.30, p = 0.002) and inferior frontal gyrus (β = −0.28, p = 0.004). Aberrant motor behavior was associated with atrophy of frontal pole (β = −0.29, p = 0.005) and the subcallosal area (β = −0.39, p < 0.001). No significant associations with frontal brain volumes were found for agitation and irritability. We conclude that the subcallosal area may be common neuroanatomical area for behavioral symptoms in neurodegenerative diseases, and it appears to be independent of disease etiology.

Prodromal and Early bvFTD: Evaluating Clinical Features and Current Biomarkers

Despite the current diagnostic criteria, early diagnostics of behavioral variant of frontotemporal dementia (bvFTD) has remained challenging. Patients with bvFTD often present with misleading psychiatric phenotype, and, on the other hand, impairment in memory functions have increasingly been reported. However, impaired episodic memory is currently considered as an exclusion criterion for bvFTD. Single biofluid-based or imaging biomarkers do not currently provide sufficient sensitivity or specificity for early bvFTD diagnosis at single-subject level, although studies have suggested improved accuracy with different biomarker combinations. In this mini review, we evaluate the core clinical features of early bvFTD and summarize the most potential imaging and fluid biomarkers for bvFTD diagnostics.

Astrocytes and Microglia as Potential Contributors to the Pathogenesis of C9orf72 Repeat Expansion-Associated FTLD and ALS

Frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative diseases with a complex, but often overlapping, genetic and pathobiological background and thus they are considered to form a disease spectrum. Although neurons are the principal cells affected in FTLD and ALS, increasing amount of evidence has recently proposed that other central nervous system-resident cells, including microglia and astrocytes, may also play roles in neurodegeneration in these diseases. Therefore, deciphering the mechanisms underlying the disease pathogenesis in different types of brain cells is fundamental in order to understand the etiology of these disorders. The major genetic cause of FTLD and ALS is a hexanucleotide repeat expansion (HRE) in the intronic region of the C9orf72 gene. In neurons, specific pathological hallmarks, including decreased expression of the C9orf72 RNA and proteins and generation of toxic RNA and protein species, and their downstream effects have been linked to C9orf72 HRE-associated FTLD and ALS. In contrast, it is still poorly known to which extent these pathological changes are presented in other brain cells. Here, we summarize the current literature on the potential role of astrocytes and microglia in C9orf72 HRE-linked FTLD and ALS and discuss their possible phenotypic alterations and neurotoxic mechanisms that may contribute to neurodegeneration in these diseases.

Automatic MRI Quantifying Methods in Behavioral-Variant Frontotemporal Dementia Diagnosis

Aims

We assessed the value of automated MRI quantification methods in the differential diagnosis of behavioral-variant frontotemporal dementia (bvFTD) from Alzheimer disease (AD), Lewy body dementia (LBD), and subjective memory complaints (SMC). We also examined the role of the C9ORF72-related genetic status in the differentiation sensitivity.

Methods

The MRI scans of 50 patients with bvFTD (17 C9ORF72 expansion carriers) were analyzed using 6 quantification methods as follows: voxel-based morphometry (VBM), tensor-based morphometry, volumetry (VOL), manifold learning, grading, and white-matter hyperintensities. Each patient was then individually compared to an independent reference group in order to attain diagnostic suggestions.

Results

Only VBM and VOL showed utility in correctly identifying bvFTD from our set of data. The overall classification sensitivity of bvFTD with VOL + VBM achieved a total sensitivity of 60%. Using VOL + VBM, 32% were misclassified as having LBD. There was a trend of higher values for classification sensitivity of the C9ORF72 expansion carriers than noncarriers.

Conclusion

VOL, VBM, and their combination are effective in differential diagnostics between bvFTD and AD or SMC. However, MRI atrophy profiles for bvFTD and LBD are too similar for a reliable differentiation with the quantification methods tested in this study.