Search

BackgroundThe etiology of frontotemporal dementia (FTD) is poorly understood. To identify genes with predicted expression levels associated with FTD, we integrated summary statistics with external reference gene expression data using a transcriptome-wide association study approach.MethodsFUSION software was used to leverage FTD summary statistics (all FTD: n = 2154 cases, n = 4308 controls; behavioral variant FTD: n = 1337 cases, n = 2754 controls; semantic dementia: n = 308 cases, n = 616 controls; progressive nonfluent aphasia: n = 269 cases, n = 538 controls; FTD with motor neuron disease: n = 200 cases, n = 400 controls) from the International FTD-Genomics Consortium with 53 expression quantitative loci tissue type panels (n = 12,205; 5 consortia). Significance was assessed using a 5% false discovery rate threshold.ResultsWe identified 73 significant gene-tissue associations for FTD, representing 44 unique genes in 34 tissue types. Most significant findings were derived from dorsolateral prefrontal cortex splicing data (n = 19 genes, 26%). The 17q21.31 inversion locus contained 23 significant associations, representing 6 unique genes. Other top hits included SEC22B (a gene involved in vesicle trafficking), TRGV5, and ZNF302. A single gene finding (RAB38) was observed for behavioral variant FTD. For other clinical subtypes, no significant associations were observed.ConclusionsWe identified novel candidate genes (e.g., SEC22B) and previously reported risk regions (e.g., 17q21.31) for FTD. Most significant associations were observed in dorsolateral prefrontal cortex splicing data despite the modest sample size of this reference panel. This suggests that our findings are specific to FTD and are likely to be biologically relevant highlights of genes at different FTD risk loci that are contributing to the disease pathology.

Abstract Background APP duplication is a rare genetic cause of Alzheimer disease and cerebral amyloid angiopathy (CAA). We aimed to evaluate the phenotypes of APP duplications carriers. Methods Clinical, radiological, and neuropathological features of 43 APP duplication carriers from 24 French families were retrospectively analyzed, and MRI features and cerebrospinal fluid (CSF) biomarkers were compared to 40 APP-negative CAA controls. Results Major neurocognitive disorders were found in 90.2% symptomatic APP duplication carriers, with prominent behavioral impairment in 9.7%. Symptomatic intracerebral hemorrhages were reported in 29.2% and seizures in 51.2%. CSF Aβ42 levels were abnormal in 18/19 patients and 14/19 patients fulfilled MRI radiological criteria for CAA, while only 5 displayed no hemorrhagic features. We found no correlation between CAA radiological signs and duplication size. Compared to CAA controls, APP duplication carriers showed less disseminated cortical superficial siderosis (0% vs 37.5%, p = 0.004 adjusted for the delay between symptoms onset and MRI). Deep microbleeds were found in two APP duplication carriers. In addition to neurofibrillary tangles and senile plaques, CAA was diffuse and severe with thickening of leptomeningeal vessels in all 9 autopsies. Lewy bodies were found in substantia nigra, locus coeruleus, and cortical structures of 2/9 patients, and one presented vascular amyloid deposits in basal ganglia. Discussion Phenotypes associated with APP duplications were heterogeneous with different clinical presentations including dementia, hemorrhage, and seizure and different radiological presentations, even within families. No apparent correlation with duplication size was found. Amyloid burden was severe and widely extended to cerebral vessels as suggested by hemorrhagic features on MRI and neuropathological data, making APP duplication an interesting model of CAA.

Abstract Abnormal mitochondrial function has been found in patients with frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Mutations in the p62 gene (also known as SQSTM1) which encodes the p62 protein have been reported in both disorders supporting the idea of an ALS/FTD continuum. In this work the role of p62 in energy metabolism was studied in fibroblasts from FTD patients carrying two independent pathogenic mutations in the p62 gene, and in a p62-knock-down (p62 KD) human dopaminergic neuroblastoma cell line (SH-SY5Y). We found that p62 deficiency is associated with inhibited complex I mitochondrial respiration due to lack of NADH for the electron transport chain. This deficiency was also associated with increased levels of NADPH reflecting a higher activation of pentose phosphate pathway as this is accompanied with higher cytosolic reduced glutathione (GSH) levels. Complex I inhibition resulted in lower mitochondrial membrane potential and higher cytosolic ROS production. Pharmacological activation of transcription factor Nrf2 increased mitochondrial NADH levels and restored mitochondrial membrane potential in p62-deficient cells. Our results suggest that the phenotype is caused by a loss-of-function effect, because similar alterations were found both in the mutant fibroblasts and the p62 KD model. These findings highlight the implication of energy metabolism in pathophysiological events associated with p62 deficiency.

Background: The diagnosis of behavioral variant of frontotemporal dementia (bvFTD) relies primarily on clinical features and remains challenging. The specificity of the recently revised criteria can be disappointing, justifying development of new clinical tools. Objective: We produced a behavioral inventory named DAPHNE. This scale (adapted from Rascovsky's criteria) explores six domains: disinhibition, apathy, perseverations, hyperorality, personal neglect and loss of empathy. It is composed of ten items (five answer categories). The aim was (1) to assess the validity and reliability of DAPHNE and (2) to evaluate its contribution in differentiating patients. Methods: Two scores were computed: DAPHNE-6 (screening) from the six domains and DAPHNE-40 (diagnosis) from the ten items. Reliability and reproducibility were assessed. External validity was studied with the Frontal Behavioral Inventory (FBI) and the Frontotemporal Behavioral Scale (FBS). Finally, the diagnostic performance of DAPHNE was compared to revised criteria, FBI and FBS. Results: DAPHNE was administered to the caregivers of 89 patients, 36 with bvFTD, 22 with Alzheimer's disease, 15 with progressive supranuclear palsy and 16 with bipolar disorder. Reliability and reproducibility were excellent, as was external validity. DAPHNE-6 allowed bvFTD diagnosis (score ≥4) with a sensitivity of 92%, while DAPHNE-40 (score ≥15) had a specificity of 92%. Conclusion: We demonstrate excellent psychometric features for DAPHNE. This quick tool could help for both diagnosing and screening bvFTD.

BACKGROUND:Many studies have highlighted the high prevalence of executive disorders in stroke. However, major uncertainties remain due to use of variable and non-validated methods. The objectives of this study were: 1) to characterize the executive disorder profile in stroke using a standardized battery, validated diagnosis criteria of executive disorders and validated framework for the interpretation of neuropsychological data and 2) examine the sensitivity of the harmonization standards protocol proposed by the National Institute of Neurological Disorders and Stroke and Canadian Stroke Network (NINDS-CSN) for the diagnosis of Vascular Cognitive Impairment. METHODS:237 patients (infarct: 57; cerebral hemorrhage: 54; ruptured aneurysm of the anterior communicating artery (ACoA): 80; cerebral venous thrombosis (CVT): 46) were examined by using the GREFEX battery. The patients' test results were interpreted with a validated framework derived from normative data from 780 controls. RESULTS:Dysexecutive syndrome was observed in 88 (55.7%; 95%CI: 48-63.4) out of the 156 patients with full cognitive and behavioral data: 40 (45.5%) had combined behavioral and cognitive syndromes, 29 (33%) had a behavioral disorder alone and 19 (21.6%) had a cognitive syndrome alone. The dysexecutive profile was characterized by prominent impairments of initiation and generation in the cognitive domain and by hypoactivity with disinterest and anticipation loss in the behavioral domain. Cognitive impairment was more frequent (p = 0.014) in hemorrhage and behavioral disorders were more frequent (p = 0.004) in infarct and hemorrhage. The harmonization standards protocol underestimated (p = 0.007) executive disorders in CVT or ACoA. CONCLUSIONS:This profile of executive disorders implies that the assessment should include both cognitive tests and a validated inventory for behavioral dysexecutive syndrome. Initial assessment may be performed with a short cognitive battery, such as the harmonization standards protocol. However, administration of a full cognitive battery is required in selected patients.