Maura Cosseddu

Granulin mutation drives brain damage and reorganization from preclinical to symptomatic FTLD

Granulin (GRN) mutations have been identified as a major cause of frontotemporal lobar degeneration (FTLD) by haploinsufficiency mechanism, although their effects on brain tissue dysfunction and damage still remain to be clarified. In this study, we investigated the pattern of neuroimaging abnormalities in FTLD patients, carriers and noncarriers of GRN Thr272fs mutation, and in presymptomatic carriers. We assessed regional gray matter (GM) atrophy, and resting (RS)-functional magnetic resonance imaging (fMRI). The functional connectivity maps of the salience (SN) and the default mode (DMN) networks were considered. Frontotemporal gray matter atrophy was found in all FTLD patients (more remarkably in those GRN Thr272fs carriers), but not in presymptomatic carriers. Functional connectivity within the SN was reduced in all FTLD patients (again more remarkably in those mutation carriers), while it was enhanced in the DMN. Conversely, presymptomatic carriers showed increased connectivity in the SN, with no changes in the DMN. Our findings suggest that compensatory mechanisms of brain plasticity are present in GRN-related FTLD, but with different patterns at a preclinical and symptomatic disease stage.

The FTLD-modified Clinical Dementia Rating scale is a reliable tool for defining disease severity in Frontotemporal Lobar Degeneration: evidence from a brain SPECT study

Background:  Frontotemporal Lobar Degeneration (FTLD) is a heterogeneous disorder characterized by impairment in executive functions, behavioural disturbance and language deficit. Reliable scales of global impairment are under evaluation. A consortium of Mayo Clinic and University of California FTLD Centers has recently developed the FTLD‐modified Clinical Dementia Rating (CDR) scale to assess FTLD severity.

Pattern of behavioral disturbances in corticobasal degeneration syndrome and progressive supranuclear palsy.

BACKGROUND A careful characterization of behavioral abnormalities in corticobasal degeneration syndrome (CBDS) and progressive supranuclear palsy (PSP) by reliable tools is still lacking. Literature data provided evidence of the usefulness of the Frontal Behavioral Inventory (FBI) to operationalize such disturbances, particularly in the frontotemporal lobar degeneration spectrum. The study aimed to evaluate the frequency and pattern of presentation of behavioral disturbances in a large sample of CBDS and PSP patients by FBI. METHODS Sixty-eight CBDS and 57 PSP patients entered the study and underwent a standardized clinical and neuropsychological battery, and a structural brain imaging study. Behavioral disturbances were carefully analyzed by FBI. RESULTS FBI scores were relatively low in both groups, being 6.7 +/- 8.2 and 5.6 +/- 6.1 in CBDS and PSP, respectively. Comparison of the behavioral profile between CBDS and PSP patients showed significant differences in apathy were more frequent in the latter (57.9% vs. 33.8%, P = 0.007), and the presence of alien hand/apraxia more frequent in the former group 39.7% vs. 10.5%, P = 0.001). Apathy correlated neither with age nor with motor disturbances as measured by UPDRS-III. Overall, the most frequent behavioral abnormalities present in both groups (>25%) were aspontaneity and logopenia. Aphasia (27.9%) and irritability (35.3%) were more frequent in CBDS compared to PSP, even if not statistically different. DISCUSSION The present study has provided measures of behavioral disturbances in a population of PSP and CBDS patients, and further confirms the usefulness of the FBI scale.

Prefrontal cortex rTMS enhances action naming in progressive non‐fluent aphasia

Background and purpose: Progressive non‐fluent aphasia (PNFA) is a neurodegenerative disorder that is characterized by non‐fluent speech with naming impairment and grammatical errors. It has been recently demonstrated that repetitive transcranial magnetic stimulation (rTMS) over the dorsolateral prefrontal cortex (DLPFC) improves action naming in healthy subjects and in subjects with Alzheimer’s disease.

The Speech and Language FOXP2 Gene Modulates the Phenotype of Frontotemporal Lobar Degeneration

The FOXP2 gene is mutated in a severe monogenic form of speech and language deficits, but no study on the influence of genetic variations within FOXP2 in neurological disorders characterized by language impairment is available yet. In the present study, we investigated the impact of common FOXP2 polymorphisms with regard to frontotemporal lobar degeneration (FTLD). Two-hundred ten FTLD patients underwent clinical and a wide standardized neuropsychological examination as well as brain imaging. In all patients, and in 200 age-matched healthy controls, four FOXP2 polymorphisms were evaluated, namely rs2396753, rs1456031, rs17137124 and rs1852469. SPECT images were analyzed by Statistical Parametric Mapping (SPM5). No significant differences of the four FOXP2 polymorphisms in genotype distribution and allele frequency between FTLD and controls were observed. A significant and specific association between rs1456031 TT and rs17137124 TT genotypes and verbal fluency scores was reported. The two polymorphisms showed an addictive effect. When the analysis was computed on the number of observations over time, and 391 assessments considered, comparable results were obtained. FTLD patients carrying at-risk polymorphisms showed greater hypoperfusion in the frontal areas, namely the left inferior frontal gyrus, and putamen, compared to the non-carriers (p < 0.005). Genetic variations within FOXP2 do not represent a genetic risk to FTLD per se, but modulate FTLD presentation when disease is overt, affecting language performances and leading to hypoperfusion in language-associated brain areas.

Transcranial magnetic stimulation distinguishes Alzheimer disease from frontotemporal dementia

Objective: To determine whether a transcranial magnetic stimulation (TMS) multiparadigm approach can be used to distinguish Alzheimer disease (AD) from frontotemporal dementia (FTD). Methods: Paired-pulse TMS was used to investigate short-interval intracortical inhibition (SICI) and facilitation (ICF), long-interval intracortical inhibition, and short-latency afferent inhibition (SAI) to measure the activity of different intracortical circuits in patients with AD, patients with FTD, and healthy controls (HC). The primary outcome measures were sensitivity and specificity of TMS measures, derived from receiver operating curve analysis. Results: A total of 175 participants met the inclusion criteria. We diagnosed 79 patients with AD, 64 patients with FTD, and 32 HC. We found that while patients with AD are characterized by a specific impairment of SAI, FTD shows a remarkable dysfunction of SICI-ICF intracortical circuits. With the use of the best indexes, TMS differentiated FTD from AD with a sensitivity of 91.8% and specificity of 88.6%, AD from HC with a sensitivity of 84.8% and specificity of 90.6%, and FTD from HC with a sensitivity of 90.2% and specificity of 78.1%. These results were confirmed in patients with mild disease. Conclusions: TMS is a noninvasive procedure that reliably distinguishes AD from FTD and HC and, if these findings are replicated in larger studies, could represent a useful additional diagnostic tool for clinical practice. Classification of evidence: This study provides Class III evidence that TMS measures can distinguish patients with AD from those with FTD.

Impaired long-term potentiation-like cortical plasticity in presymptomatic genetic frontotemporal dementia.

Neurophysiological biomarkers were assessed using a TMS multi-paradigm approach in thirteen presymptomatic (n=13 Granulin) and fourteen symptomatic (n=11 Granulin, n=3 C9orf72) subjects with a pathogenic mutation for Frontotemporal Dementia. Intra-cortical facilitation and LTP-like plasticity were impaired in presymptomatic carriers compared to healthy controls more than 15 years before expected symptom onset. In symptomatic carriers, a decrease in short-interval intracortical inhibition compared to presymptomatic carriers was found. In conclusion, these biomarkers could provide the footprints of specific physiopathological processes in the development of this disease and possibly support the diagnosis of autosomal dominant Frontotemporal dementia. This article is protected by copyright. All rights reserved.Neurophysiological biomarkers were assessed using a transcranial magnetic stimulation multiparadigm approach in 13 presymptomatic (n = 13 Granulin) and 14 symptomatic (n = 11 Granulin, n = 3 C9orf72) subjects with a pathogenic mutation for frontotemporal dementia (FTD). Intracortical facilitation and long‐term potentiation–like plasticity were impaired in presymptomatic carriers, compared to healthy controls, more than 15 years before expected symptom onset. In symptomatic carriers, a decrease in short‐interval intracortical inhibition, compared to presymptomatic carriers, was found. In conclusion, these biomarkers could provide the footprints of specific physiopathological processes in the development of this disease and possibly support the diagnosis of autosomal‐dominant FTD. Ann Neurol 2016;80:472–476

Vascular Risk Factors and Cognition in Parkinson’s Disease

Vascular risk factors have been associated with cognitive deficits and incident dementia in the general population, but their role on cognitive dysfunction in Parkinsons disease (PD) is still unclear. The present study addresses the single and cumulative effect of vascular risk factors on cognition in PD patients, taking clinical confounders into account. Standardized neuropsychological assessment was performed in 238 consecutive PD patients. We evaluated the association of single and cumulative vascular risk factors (smoking, diabetes, hypercholesterolemia, hypertension, and heart disease), with the diagnosis of PD normal cognition (PDNC, n = 94), mild cognitive impairment (PD-MCI, n = 111), and dementia (PDD, n = 33). The association between single neuropsychological tests and vascular risk factors was evaluated with covariance analyses adjusted for age at onset, educational levels, gender, disease duration, and motor performance. Age, educational levels, disease duration, and motor function were significantly different between PDNC, PD-MCI, and PDD. Heart disease was the only vascular factor significantly more prevalent in PDD compared with PDNC in adjusted analyses. Performance of tests assessing executive and attention functions were significantly worse in patients with hypertension, heart disease, and/or diabetes (p <  0.05). Heart disease is associated with dementia in PD, suggesting a potential window of intervention. Vascular risk factors act especially on attention and executive functions in PD. Vascular risk stratification may be useful in order to identify PD patients with a greater risk of developing dementia. These findings need to be verified in longitudinal studies.

Left parietal cortex transcranial direct current stimulation enhances gesture processing in corticobasal syndrome

Corticobasal syndrome (CBS) is a clinical entity characterized by higher cortical dysfunctions associated with asymmetric onset of levodopa‐resistant parkinsonism, dystonia and myoclonus. One of the most typical and distressful features of CBS is limb apraxia, which affects patients in their everyday life. Transcranial direct current stimulation (tDCS) is a non‐invasive procedure of cortical stimulation, which represents a promising tool for cognitive enhancement and neurorehabilitation. The present study investigated whether anodal tDCS over the parietal cortex (PARC), would improve ideomotor upper limb apraxia in CBS patients.

Iron in Frontotemporal Lobar Degeneration: A New Subcortical Pathological Pathway?

Introduction: Brain iron homeostasis dysregulation has been widely related to neurodegeneration. In particular, human haemochromatosis protein (HFE) is involved in iron metabolism, and HFE H63D polymorphism has been related to the risk of amyotrophic lateral sclerosis and Alzheimers disease. Recently, iron accumulation in the basal ganglia of frontotemporal lobar degeneration (FTLD) patients has been described. Objective: To explore the relationship between HFE genetic variation and demographic, clinical and imaging characteristics in a large cohort of FTLD patients. Methods: A total of 110 FTLD patients underwent neuropsychological and imaging evaluation and blood sampling for HFE polymorphism determination. HFE H63D polymorphism was considered in the present study. Two imaging approaches were applied to evaluate the effect of HFE genetic variation on brain atrophy, namely voxel-based morphometry and region of interest-based probabilistic approach (SPM8; Wellcome Trust Centre for Neuroimaging). Results: FTLD patients carrying the D* genotype (H/D or D/D) showed greater atrophy in the basal ganglia, bilaterally, compared to H/H carriers (x, y, z: -22, -4, 0; T = 3.45; cluster size: 33 voxels, x, y, z: 24, 4, -2; T = 3.38; cluster size: 36 voxels). The former group had even more pronounced behavioural symptoms, as defined by the Frontal Behavioural Inventory total scores. Conclusions: Our data suggest that H63D polymorphism could represent a disease-modifying gene in FTLD, fostering iron deposition in the basal ganglia. This suggests a new possible mechanism of FTLD-associated neurodegeneration.