Fluorodeoxyglucose positron emission tomography in semantic dementia after 6 months of memantine: an open-label pilot study

Alzheimer's Dementia: The Emerging Role of Positron Emission Tomography

Alzheimer's disease (AD) is the most common cause of dementia and accounts for approximately 50% to 80% of all cases of dementia. The diagnosis of probable AD is based on clinical criteria and overlapping clinical features pose a challenge to accurate diagnosis. However, neuroimaging has been included as a biomarker in various published criteria for the diagnosis of probable AD, in the absence of a confirmatory diagnostic test during life. Advances in neuroimaging techniques and their inclusion in diagnostic and research criteria for the diagnosis of AD includes the use of positron emission tomography (PET) imaging as a biomarker in various therapeutic and prognostic studies in AD. The development and application of a range of PET tracers will allow more detailed assessment of people with AD and will improve diagnostic specificity and targeted therapy of AD. The aim of this review is to summarize current evidence on PET imaging using the non-specific tracer [18F]fluorodeoxyglucose and specific tracers that target amyloid and tau pathology in people with AD.

[Contemporary approaches to clinical diagnosis and treatment of tau-protein accumulation related multisystem degenerations]

Tau-protein pathology is the basis of a great variety of neurodegenerative diseases. Misfolding tau-protein conformation structure is the key pathogenetic mechanism of development of such multisystem degenerations as progressive supranuclear palsy, corticobasal syndrome, and fronto-temporal degeneration, as well as relatively recently added primary age-associated tauopathies and others. This review presents current views on the pathogenesis of various forms of neurodegenerative pathology linked to tau-protein accumulation. Potential of clinical diagnosis and modern diagnostic criteria, as well as existing therapy approaches, are discussed.

[Speech disorders in neurodegenerative diseases as dysphasia manifestation]

OBJECTIVE

To develop the classification and methodology for assessment of speech disorders in neurodegenerative diseases, and to identify the characteristics of speech disorders for various forms.

MATERIALS AND METHODS

The study included 1016 patients with neurodegenerative diseases. Screening assessment identified 42.1% patients with speech disorders exceeding isolated dysarthria. Patients were assessed using the speech disorder test battery developed by the authors. Cluster, multifactor and contingency analyses were performed.

RESULTS

Nine subtypes of speech disorders were identified in neurodegenerative diseases that we denominated as dysphasia. Based on contingency analysis, the principal and the additional dysphasia variants were identified for each form of neurodegenerative pathology, which may contribute to better understanding of various phenotypes. Based on the general scheme of speech origination, the level of disorders typical for a given dysphasia subtype was identified.

CONCLUSION

The proposed classification enables identification of the subtypes of speech disorders for individual forms of neurodegenerative diseases. Introducing dysphasia concept to clinical practice will improve differential diagnosis and understanding of phenotypical heterogeneity of each nosological form as well as will facilitate therapy optimization.

[Current approaches to the treatment of fronto-temporal dementia]

Frontotemporal dementias (FTD) are one of the prevalent forms of early neurodegenerative diseases. FTD are characterized by heterogeneous clinical manifestations and syndromes. The current methods of FTD treatment and the clinical trials of new methods of FTD treatment are considered in the article. Biomarkers and their relationships with the results of recently completed clinical trials, as well as future therapeutic perspectives, are reviewed.

The emerging role of PET imaging in dementia

A compelling need in the field of neurodegenerative diseases is the development and validation of biomarkers for early identification and differential diagnosis. The availability of positron emission tomography (PET) neuroimaging tools for the assessment of molecular biology and neuropathology has opened new venues in the diagnostic design and the conduction of new clinical trials. PET techniques, allowing the in vivo assessment of brain function and pathology changes, are increasingly showing great potential in supporting clinical diagnosis also in the early and even preclinical phases of dementia. This review will summarize the most recent evidence on fluorine-18 fluorodeoxyglucose-, amyloid -, tau -, and neuroinflammation - PET tools, highlighting strengths and limitations and possible new perspectives in research and clinical applications. Appropriate use of PET tools is crucial for a prompt diagnosis and target evaluation of new developed drugs aimed at slowing or preventing dementia.

Efficacy of memantine on neuropsychiatric symptoms associated with the severity of behavioral variant frontotemporal dementia: A six-month, open-label, self-controlled clinical trial

Previous studies have focused on the curative effects of memantine in patients with mild-to-moderate frontotemporal lobar degeneration (FTLD); however, its benefits in patients with moderate-to-severe FTLD have not been investigated. The present study explores the behavioral, cognitive and functional effects of memantine on behavioral variant frontotemporal dementia (bvFTD) in patients with mild and moderate-to-severe stage bvFTD. A total of 42 patients with bvFTD completed a 6-month treatment plan of 20 mg memantine daily in an open-label, self-controlled clinical trial. Patients were divided into two groups according to their Mini-Mental State Examination (MMSE) score: Mild (score, 21-26); and moderate-to-severe (score, 4-20). Primary endpoints included Neuropsychiatric Inventory Questionnaire (NPI-Q) and Clinic Dementia Rating (CDR) scores, and secondary endpoints comprised Neuropsychiatric Inventory Caregiver Distress Scale (NPI-D), MMSE, Montreal Cognitive Assessment (MoCA), Activity of Daily Life (ADL) and Hamilton Depression Rating Scale (HAMD) scores. Memantine treatment had no effect on overall NPI-Q scores, with the exception of the agitation subdomain in all patients with bvFTD. However, patients with moderate-to-severe bvFTD exhibited a better performance than patients with mild bvFTD, demonstrated by improved NPI-Q total scores and subscales of agitation, depression, apathy and disinhibition. In the moderate-to-severe group, CDR and HAMD scores remained stable, but MMSE, MoCA and ADL scores were reduced after 6 months of treatment. Memantine was well-tolerated in patients. In conclusion, patients with moderate-to-severe bvFTD responded significantly better to memantine in comparison to patients with mild bvFTD with regard to their neuropsychiatric scores, while memantine did not present any cognitive or functional benefits in patients with mild bvFTD. A randomized, double-blind, placebo-controlled clinical trial with a larger number of patients is required to verify these promising results for patients with moderate-to-severe bvFTD.

Role of positron emission tomography/computed tomography in dementia

This article provides a clinically based review of positron emission tomography (PET) imaging for dementia. Significant advances in nuclear medicine and molecular imaging techniques have improved the understanding of the genetic and molecular processes that define neurodegenerative dementia diseases. Metabolic imaging remains constant in its ability to document neuronal loss and lost function. Amyloid-β radiotracers are useful in documenting amyloid deposition, differentiating origins of dementia and possibly predicting disease progression. These radiotracers may be useful in diagnosis-specific treatment. PET radiotracers have increased sensitivity and specificity to complement clinical presentation and other adjunct testing in the evaluation of dementia.