Risk of dementia associated with elevated plasma homocysteine in a latin american population

Identification of biomarkers for vascular dementia: a literature review

Alzheimer's disease and vascular dementia are the two most common types of dementia. It becomes difficult to distinguish between the two, especially when there are no specific genetic causes or vascular changes apparent. The aim of this review was to identify specific biomarkers supporting the diagnosis of vascular dementia by conducting a literature search for systematic reviews and observational studies. We found seven studies meeting our inclusion/exclusion criteria, and from these we identified four specific biomarkers supporting the diagnosis of vascular dementia: high levels of thyroid-stimulating hormone, lipoprotein(a), homocysteine and N-terminal prosomatostatin. However, the studies were small and a well-conducted study with larger populations is recommended to strengthen the evidence base.

Research on aging during the Venezuelan humanitarian crisis: the experience of the Maracaibo aging study

BACKGROUND

Venezuela is in the throes of a complex humanitarian crisis that is one of the worst in decades to impact any country outside of wartime. This case analysis describes the challenges faced by the ongoing Maracaibo Aging Study (MAS) during the deteriorating conditions in Venezuela. When the MAS began in 1997, it focused on memory-related disorders. Since then, strategic planning and proactive community participation allowed us to anticipate and address logistical, funding, and ethical challenges, and facilitated the enrollment and retention of more than 2500 subjects over 55 years of age. All participants, who are residents of the city of Maracaibo, Venezuela, underwent various assessments on several occasions. Here, we discuss how our approach to implementing a longitudinal, population-based study of age-related conditions has allowed our research program to continue throughout this period of political, economic, and social upheaval.

DISCUSSION

As the social context in Venezuela became more complicated, new challenges emerged, and strategies to sustain the study and participation were refined. We identified five main mechanisms through which the evolving humanitarian crisis has affected implementation of the MAS: 1) community dynamics; 2) morale of researchers, staff, and participants; 3) financial feasibility; 4) components of the research process; and 5) impact on the health of staff, participants, and their families. Strategies to compensate for the impact on these components were implemented, based on inputs from community members and staff. Improved communication, greater involvement of stakeholders, broadening the scope of the project, and strengthening international collaboration have been the most useful strategies. Particular demands emerged, related to the increased mortality and comorbidities of participants and staff, and deterioration of basic services and safety.

CONCLUSION

Although the MAS has faced numerous obstacles, it has been possible to continue a longitudinal research project throughout the humanitarian crisis, because our research team has engaged the community deeply and developed a sense of mutual commitment, and also because our project has provided funding to help keep researchers employed, somewhat attenuating the brain drain.

Biomarkers in Alzheimer's, Frontotemporal, Lewy Body, and Vascular Dementias

This article reviews the current evidence base for biomarkers of the most common causes of dementia in later life: Alzheimer's disease (AD), frontotemporal lobar degenerations, Lewy body dementias, and vascular cognitive impairment and dementia. Biomarkers are objectively measurable indicators of normal physiology, pathological processes, or response to an intervention. Ideally, they are sensitive, specific, easy to obtain, and closely reflect the underlying biological processes of interest. While such markers are well established and in broad clinical use for common disorders in general medicine (e.g., thallium stress tests for coronary artery disease or serum blood urea nitrogen and creatinine for renal failure), analogous, validated markers for AD or other common dementias are limited, although biomarkers in research settings and specialty dementia clinics are progressing toward clinical use. By way of introducing current and future biomarkers for dementias of later life, this article will benefit the practicing clinician by increasing awareness of the availability and utility of current and emerging biomarkers in dementia diagnosis and prognosis and for monitoring new disease-modifying therapeutics that arrive in the clinic over the coming decade.

Oxidative and Nitrosative Stress and Immune-Inflammatory Pathways in Patients with Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS)

Myalgic Encephalomyelitis (ME) / Chronic Fatigue Syndrome (CFS) has been classified as a disease of the central nervous system by the WHO since 1969. Many patients carrying this diagnosis do demonstrate an almost bewildering array of biological abnormalities particularly the presence of oxidative and nitrosative stress (O&NS) and a chronically activated innate immune system. The proposal made herein is that once generated chronically activated O&NS and immune-inflammatory pathways conspire to generate a multitude of self-sustaining and self-amplifying pathological processes which are associated with the onset of ME/CFS. Sources of continuous activation of O&NS and immune-inflammatory pathways in ME/CFS are chronic, intermittent and opportunistic infections, bacterial translocation, autoimmune responses, mitochondrial dysfunctions, activation of the Toll-Like Receptor Radical Cycle, and decreased antioxidant levels. Consequences of chronically activated O&NS and immune-inflammatory pathways in ME/CFS are brain disorders, including neuroinflammation and brain hypometabolism / hypoperfusion, toxic effects of nitric oxide and peroxynitrite, lipid peroxidation and oxidative damage to DNA, secondary autoimmune responses directed against disrupted lipid membrane components and proteins, mitochondrial dysfunctions with a disruption of energy metabolism (e.g. compromised ATP production) and dysfunctional intracellular signaling pathways. The interplay between all of these factors leads to self-amplifying feed forward loops causing a chronic state of activated O&NS, immune-inflammatory and autoimmune pathways which may sustain the disease.

Serum Homocysteine, Dehydroepiandrosterone Sulphate and Lipoprotein (a) in Alzheimer's Disease and Vascular Dementia

Alzheimer's disease (AD) and vascular dementia (VAD) are the major forms of dementia affecting elderly people, in which the levels of many metabolites are altered in cerebrospinal fluid (CSF) and serum. These metabolites could be risk factors or potential biomarkers, but the significance of some of these are not clearly understood in the context of the disease pathogenesis. In the present study serum levels of homocysteine, dehydroepiandrosterone sulphate (DHEA-S) and lipoprotein (a) or Lp(a) have been measured by ELISA using commercial kits in AD (n = 40), VAD (n = 40) and age matched control subjects (n = 40). The data are compared by ANOVA and post-hoc analysis. The serum homocysteine is markedly elevated compared to control both in AD and VAD subjects, but to a significantly higher extent in the latter. Lp(a) is increased in the serum of VAD subjects only compared to control. Likewise, serum DHEA-S level is lowered in AD but not in VAD compared to control. The analysis of the present data and those published by others suggest that alterations in homocysteine and Lp(a) in serum are indicators of vascular pathology in AD or VAD, while the lowering of serum DHEA-S is a consequence of AD pathology.