Frequency of C9orf72, GRN, and MAPT pathogenic variants in patients recruited at the Belgrade Memory Center.

Most of the heritability in frontotemporal dementia (FTD) is accounted for by autosomal dominant hexanucleotide expansion in the chromosome 9 open reading frame 72 (C9orf72), pathogenic/likely pathogenic variants in progranulin (GRN), and microtubule-associated protein tau (MAPT) genes. Until now, there has been no systematic analysis of these genes in the Serbian population. Herein, we assessed the frequency of the C9orf72 expansion, pathogenic/likely pathogenic variants in GRN and MAPT in a well-characterized group of 472 subjects (FTD, Alzheimer's disease - AD, mild cognitive impairment - MCI, and unspecified dementia - UnD), recruited in the Memory Center, Neurology Clinic, University Clinical Center of Serbia. The C9orf72 repeat expansion was detected in 6.98% of FTD cases (13.46% familial; 2.6% sporadic). In the UnD subgroup, C9orf72 repeat expansions were detected in 4.08% (8% familial) individuals. Pathogenic variants in the GRN were found in 2.85% of familial FTD cases. Interestingly, no MAPT pathogenic/likely pathogenic variants were detected, suggesting possible geographical specificity. Our findings highlight the importance of wider implementation of genetic testing in neurological and psychiatric practice managing patients with cognitive-behavioral and motor symptoms.

Clusters of cognitive impairment among different phenotypes of myotonic dystrophy type 1 and type 2.

Neuropsychological examinations in myotonic dystrophy (DM) patients show a great variability of results from a condition of intellectual disability to the subtle cognitive impairments. It is unclear if different clusters of neuropsychological deficits appear in different phenotypes of DM, or if there are patients with no cognitive deficit at all. The aim of this study is to assess cognitive impairments among patients with different phenotypes of DM type 1 (DM1) and type 2 (DM2), and to potentially define cognitive clusters in these disorders. Study comprised 101 DM1 and 46 DM2 adult patients who were genetically confirmed. Patients underwent analysis of five cognitive domains (visuospatial, executive, attention, memory and language). Virtually all DM1 patients had cognitive defect with approximately 2-3 cognitive domains affected. On the other hand, one-third of DM2 patients had completely normal neuropsychological findings, and in other two-thirds approximately 1-2 domains were affected. Cluster analysis showed that in both diseases visuospatial and executive dysfunctions seemed to be the main cognitive defects, while memory and language impairments appeared in more severe phenotypes. Our results showed that a single form of DM1 or DM2 may consist of several cognitive clusters. Understanding of cognitive impairments in DM is very important to follow positive and side effects in ongoing and future clinical trials.

The impact of automated hippocampal volumetry on diagnostic confidence in patients with suspected Alzheimer's disease: A European Alzheimer's Disease Consortium study.

INTRODUCTION: Hippocampal volume is a core biomarker of Alzheimer's disease (AD). However, its contribution over the standard diagnostic workup is unclear. METHODS: Three hundred fifty-six patients, under clinical evaluation for cognitive impairment, with suspected AD and Mini-Mental State Examination ≥20, were recruited across 17 European memory clinics. After the traditional diagnostic workup, diagnostic confidence of AD pathology (DCAD) was estimated by the physicians in charge. The latter were provided with the results of automated hippocampal volumetry in standardized format and DCAD was reassessed. RESULTS: An increment of one interquartile range in hippocampal volume was associated with a mean change of DCAD of -8.0% (95% credible interval: [-11.5, -5.0]). Automated hippocampal volumetry showed a statistically significant impact on DCAD beyond the contributions of neuropsychology, 18F-fluorodeoxyglucose positron emission tomography/single-photon emission computed tomography, and cerebrospinal fluid markers (-8.5, CrI: [-11.5, -5.6]; -14.1, CrI: [-19.3, -8.8]; -10.6, CrI: [-14.6, -6.1], respectively). DISCUSSION: There is a measurable effect of hippocampal volume on DCAD even when used on top of the traditional diagnostic workup.

Screening for C9orf72 Expansion Mutation in Serbian Patients with Early-Onset Dementia.

BACKGROUND: Frontotemporal dementia (FTD) is the second most common cause of early-onset dementia (EOD), characterized by behavioral changes (behavioral variant; bvFTD) or language deficits. A hexanucleotide repeat expansion in a noncoding region of chromosome 9 open reading frame 72 (C9orf72) has been proved to be a major cause of both familial and sporadic amyotrophic lateral sclerosis or FTD, with or without concomitant motor neuron disease (MND). METHODS: The aim of this study was to assess the frequency of the C9orf72 hexanucleotide expansion in a cohort of 117 Serbian patients with EOD and to report phenotypic features of identified carriers. RESULTS: We identified 4 of 117 (3.4%) patients with EOD to have C9orf72 hexanucleotide expansions. All patients were classified in the FTD disease spectrum group (8.2%): 3 patients fulfilled the criteria for bvFTD, and 1 patient had FTD-MND. None of the patients with the C9orf72 hexanucleotide expansion fulfilled the diagnostic criteria for language variants of FTD, FTD-progressive supranuclear palsy overlap syndrome, dementia with Lewy bodies or Alzheimer's dementia. CONCLUSION: In a cohort of consecutive patients with EOD, 3.4% had the C9orf72 hexanucleotide expansion with clinical phenotypes of bvFTD or an overlap of bvFTD and MND.

Heart involvement in patients with myotonic dystrophy type 2.

Myotonic dystrophy type 2 (DM2) is a slowly progressive, autosomal-dominant disease. This is a multisystemic disorder that affects the heart, which is one of the main causes of morbidity and mortality in DM2. The aim of the study was to define cardiac impairments in patients with DM2 and its association with sociodemographic and clinical features of patients. This retrospective study comprised 62 adult patients with DM2 hospitalized at the Neurology Clinic, Clinical Center of Serbia from 2013 until 2018, who underwent electrocardiography (ECG) and echocardiography examinations. Hypertension was observed in 42% of DM2 patients. One-fifth of DM2 patients had bradycardia, while other conduction and rhythm impairments were rare. Only one patient had a pacemaker implanted because of the first degree AV block associated with incomplete left bundle branch block. Echocardiography showed diastolic dysfunction of the left ventricle in 44% of patients, while systolic dysfunction was found in only 4%. Cardiomyopathy was observed in 18% of patients, of whom three-fourth had dilated type. Cardiac conduction and rhythm defects are relatively rare in DM2, while diastolic dysfunction is common. This suggests that regular ECG and echocardiography screening is needed in DM2. Adequate therapy should be introduced in patients with DM2 on time to reduce the frequency of heart complications and to prevent premature death.

Functional and structural brain networks in posterior cortical atrophy: A two-centre multiparametric MRI study.

This study identified structural and functional brain connectivity alterations in two independent samples of patients along the posterior cortical atrophy (PCA) disease course. Twenty-one PCA patients and 44 controls were recruited from two expert centres. Microstructural damage of white matter (WM) tracts was assessed using probabilistic tractography; resting state (RS) functional connectivity of brain networks was explored using a model free approach; grey matter (GM) atrophy was investigated using voxel-based morphometry. Compared with controls, common patterns of damage across PCA patients included: GM atrophy in the occipital-temporal-parietal regions; diffusion tensor (DT) MRI alterations of the corpus callosum and superior (SLF) and inferior longitudinal fasciculi (ILF) bilaterally; and decreased functional connectivity of the occipital gyri within the visual network and the precuneus and posterior cingulum within the default mode network (DMN). In PCA patients with longer disease duration and greater disease severity, WM damage extended to the cingulum and RS functional connectivity alterations spread within the frontal, dorsal attentive and salience networks. In PCA, reduced DMN functional connectivity was associated with SLF and ILF structural alterations. PCA patients showed distributed WM damage. Altered RS functional connectivity extends with disease worsening from occipital to temporo-parietal and frontostriatal regions, and this is likely to occur through WM connections. Future longitudinal studies are needed to establish trajectories of damage spreading in PCA and whether a combined DT MRI/RS functional MRI approach is promising in monitoring the disease progression.

Multiparametric MRI to distinguish early onset Alzheimer's disease and behavioural variant of frontotemporal dementia.

This prospective study explored whether an approach combining structural [cortical thickness and white matter (WM) microstructure] and resting state functional MRI can aid differentiation between 62 early onset Alzheimer's disease (EOAD) and 27 behavioural variant of frontotemporal dementia (bvFTD) patients. Random forest and receiver operator characteristic curve analyses assessed the ability of MRI in classifying the two clinical syndromes. All patients showed a distributed pattern of brain alterations relative to controls. Compared to bvFTD, EOAD patients showed bilateral inferior parietal cortical thinning and decreased default mode network functional connectivity. Compared to EOAD, bvFTD patients showed bilateral orbitofrontal and temporal cortical thinning, and WM damage of the corpus callosum, bilateral uncinate fasciculus, and left superior longitudinal fasciculus. Random forest analysis revealed that left inferior parietal cortical thickness (accuracy 0.78, specificity 0.76, sensitivity 0.83) and WM integrity of the right uncinate fasciculus (accuracy 0.81, specificity 0.96, sensitivity 0.43) were the best predictors of clinical diagnosis. The combination of cortical thickness and DT MRI measures was able to distinguish patients with EOAD and bvFTD with accuracy 0.82, specificity 0.76, and sensitivity 0.96. The diagnostic ability of MRI models was confirmed in a subsample of patients with biomarker-based clinical diagnosis. Multiparametric MRI is useful to identify brain alterations which are specific to EOAD and bvFTD. A severe cortical involvement is suggestive of EOAD, while a prominent WM damage is indicative of bvFTD.

Routine echocardiography in patients with myotonic dystrophy type 1.

BACKGROUND: Myotonic dystrophy type 1 (DM1) is an autosomal-dominant disease. One third of DM1 patients die suddenly, most of them due to the heart conduction abnormalities and arrhythmias. The aim of this study was to analyze echocardiographic findings in a large cohort of DM1 patients. METHODS: This retrospective study comprised 111 patients and 71 healthy controls (HCs) matched for gender and age. RESULTS: Mitral valve (MV) prolapse was observed in 23% of our DM1 patients vs. 8.5% of HCs (p < 0.05). Left ventricle (LV) systolic dysfunction was observed in 6% of patients and none of the HCs (p < 0.05). Frequency of diastolic dysfunction showed no significant difference between DM1 patients and HCs (8.1% vs. 15.5%, p > 0.05). Systolic dysfunction was more common in patients with severe electrocardiographic (ECG) abnormality (18.8% vs. 2.7%, p < 0.01). CONCLUSION: One fourth of DM1 patients have MV prolapse. Approximately 15% of DM1 patients have systolic or diastolic LV dysfunction. These patients should have benefit from medical therapy. Furthermore, it seems that treatment of conduction defects might prevent development of the heart failure (HF).

Frontostriatal dysexecutive syndrome: a core cognitive feature of myotonic dystrophy type 2.

The aim of this study was to assess cognitive status in a large group of patients with myotonic dystrophy type 2 (DM2) compared to type 1 (DM1) subjects matched for gender and age, using a comprehensive battery of neuropsychological tests. Thirty-four genetically confirmed adult DM2 patients were recruited and matched for gender and age with 34 adult-onset DM1 subjects. All patients underwent detailed classic pen and pencil neuropsychological investigation and also computerized automated battery-CANTAB. More than half of DM2 patients had abnormal results on executive tests [Intra/Extradimensional Set Shift (IED), Stockings of Cambridge (SOC)] and verbal episodic memory (Ray Auditory Verbal Learning Test). Regarding DM1, abnormal results in more than 50 % of subjects were achieved in even ten tests, including visuospatial, language, executive, cognitive screening and visual memory tests. Direct comparison between patient groups showed that lower percentage of DM2 patients had abnormal results on following tests: Addenbrooke's Cognitive Examination-Revised, Raven Standard Progressive Matrices, Block Design, copy and recall of Rey-Osterieth Complex Figure, number of categories and perseverative responses on Wisconsin Card Sorting Test and Boston Naming Test (p < 0.01), as well as Trail Making Test-B and Spatial Span (p < 0.05). Our results showed significant dysexecutive syndrome and certain impairment of episodic verbal memory in DM2 patients that are reflective of frontal (especially frontostriatal) and temporal lobe dysfunction. On the other hand, dysexecutive and visuospatial/visuoconstructional deficits predominate in DM1 which correspond to the frontal, parietal (and occipital) lobe dysfunction.