Omental transpositionto the brain as a surgical method for treating Alzheimer's disease

Alzheimer's Disease: A Decreased Cerebral Blood Flow to Critical Intraneuronal Elements is the Cause

Normally, an adequate cerebral blood flow arrives at individual cerebral neurons in which the blood flow augments activity of intraneuronal mitochondria, which is the source of intraneuronal ATP, the energy source of cerebral neurons. With a decrease in cerebral blood flow that can occur as a function of normal aging phenomena, less blood results in decreased mitochondria, decreased ATP, and a decrease in neuronal activity, which can eventually lead to Alzheimer’s disease. It has been found that placement of the omentum directly on an Alzheimer’s disease brain can lead to improved cognitive function.

Modifying the progression of Alzheimer's and Parkinson's disease with deep brain stimulation

At times of an aging population and increasing prevalence of neurodegenerative disorders, effective medical treatments remain limited. Therefore, there is an urgent need for new therapies to treat Alzheimer's disease (AD). Deep brain stimulation (DBS) is thought to address the neuronal network dysfunction of this disorder and may offer new therapeutic options. Preliminary evidence suggests that DBS of the fornix may have effects on cognitive decline, brain glucose metabolism, hippocampal volume and cortical grey matter volume in certain patients with mild AD. Rodent studies have shown that increase of cholinergic neurotransmitters, hippocampal neurogenesis, synaptic plasticity and reduction of amyloid plaques are associated with DBS. Currently a large phase III study of fornix DBS is assessing efficacy in patients with mild AD aged 65 years and older. The Nucleus basalis of Meynert has also been explored in a phase I study in of mild to moderate AD and was tolerated well regardless of the lack of benefit. Being an established therapy for Parkinson's Disease (PD), DBS may exert some disease-modifying traits rather than being a purely symptomatic treatment. There is evidence of dopaminergic neuroprotection in animal models and some suggestion that DBS may influence the natural progression of the disorder. Neuromodulation may possibly have beneficial effects on course of different neurodegenerative disorders compared to medical therapy alone. For dementias, functional neurosurgery may provide an adjunctive option in patient care. This article is part of the special issue entitled 'The Quest for Disease-Modifying Therapies for Neurodegenerative Disorders'.

Deep cervical lymph node ligation aggravates AD-like pathology of APP/PS1 mice

The imbalance between production and clearance of amyloid-beta (Aβ) is a key step in the onset and development of Alzheimer's disease (AD). Therefore, reducing Aβ accumulation in the brain is a promising therapeutic strategy for AD. The recently discovered glymphatic system and meningeal lymphatic vasculature have been shown to be critical for the elimination of interstitial waste products, especially Aβ, from the brain. In the present study, ligation of deep cervical lymph nodes was performed to block drainage of this system and explore the consequences on Aβ-related pathophysiology. Five-month-old APP/PS1 mice and their wild-type littermates received deep cervical lymphatic node ligation. One month later, behavioral testing and pathological analysis were conducted. Results demonstrated that ligation of dcLNs exacerbated AD-like phenotypes of APP/PS1 mice, showing more severe brain Aβ accumulation, neuroinflammation, synaptic protein loss, impaired polarization of aquaporin-4 and deficits in cognitive and exploratory behaviors. These results suggest that brain lymphatic clearance malfunction is one of the deteriorating factors in the progression of AD, and restoring its function is a potential therapeutic target against AD.

Vascular risk factors: a ticking time bomb to Alzheimer's disease

Evidence is growing that vascular risk factors (VRFs) for Alzheimer's disease (AD) affect cerebral hemodynamics to launch a cascade of cellular and molecular changes that initiate cognitive deficits and eventual progression of AD. Neuroimaging studies have reported VRFs for AD to be accurate predictors of cognitive decline and dementia. In regions that participate in higher cognitive function, middle temporal, posterior cingulate, inferior parietal and precuneus regions, and neuroimaging studies indicate an association involving VRFs, cerebral hypoperfusion, and cognitive decline in elderly individuals who develop AD. The VRF can be present in cognitively intact individuals for decades before mild cognitive deficits or neuropathological signs are manifested. In that sense, they may be "ticking time bombs" before cognitive function is demolished. Preventive intervention of modifiable VRF may delay or block progression of AD. Intervention could target cerebral blood flow (CBF), since most VRFs act to lower CBF in aging individuals by promoting cerebrovascular dysfunction.

The evolution of omentum transposition: from lymphedema to spinal cord, stroke and Alzheimer's disease

It is now well established that the omentum incorporates into its tissues a variety of biological factors that exert a favorable effect on the central nervous system. Physiological characteristics of the omentum include edema absorption, fibrotic inhibition, blood-brain barrier penetration and, of major importance, angiogenic activity. Over several decades, studies have shown increasing clinical uses of the omentum following its placement on various structures within the body. This paper details the evolution of omental transposition (OT) up to the present at which time OT is being applied to the brain of Alzheimer disease (AD) patients. Success in this area raises the possibility that the omentum may prove to be a present-day treatment for patients with AD until future pharmaceutical and/or genetic forms of treatment are developed.

Alzheimer's disease and the 'ABSENT' hypothesis: mechanism for amyloid beta endothelial and neuronal toxicity

Alzheimer's disease [AD] is the most common cause of dementia among people age 65 and older. One of the biggest stumbling blocks in developing effective drug therapy for Alzheimer's disease has been the lack of a comprehensive hypothesis that explains the mechanism behind all of the histopathological changes seen in patients suffering from Alzheimer's disease. An overview of the currently popular 'amyloid' and 'vascular' hypotheses for AD demonstrates that neither hypothesis by itself can explain all the known histopathological and biochemical lesions seen in Alzheimer's disease. The paper presents a hypothesis that tries to explain the mechanism behind almost all the histopathological changes, and varying clinical manifestations seen in both diagnosed AD and Vascular Dementia [VaD]. The new hypothesis is based on the known dual toxicity of beta amyloid to both vascular and neuronal tissues, their synergy and the resultant net effect on the onset and progression of AD. The new hypothesis therefore will be known as the Amyloid Beta Synergistic Endothelial and Neuronal Toxicity [ABSENT] hypothesis. The ABSENT hypothesis will try to show the common chemical mechanism behind almost all of the pathological changes seen in AD. According to the ABSENT hypothesis, beta amyloid itself generates all the free radicals that cause both vascular dysfunction and the neuronal damage seen in AD. The chemical mechanism proposed is based on evidence from physical chemistry experiments, calculations as well as in vitro/in vivo experiments. The ABSENT hypothesis does not favor one mode of beta amyloid-induced brain damage over the other, rather it considers the net effects of the neuronal stress/damage caused by both the cerebrovascular dysfunction and direct neurotoxicity caused by beta amyloid. The hypothesis states that each patient has a different balance of predisposing factors that modulate the extent of neurotoxicity and cerebrovascular dysfunction caused by beta amyloid and thereby explains the wide range and mixed nature of damage and dysfunction seen in the studies done on patients diagnosed with AD, VaD or 'mixed dementias'. According to the hypothesis, beta amyloid peptides are necessary if not sufficient to cause AD, VaD and mixed senile dementias. The hypothesis, therefore, proposes the term Beta Amyloid Dementias [BAD] to describe the conditions currently covered by the diagnoses of 'AD', 'VaD' and 'Mixed [senile] Dementias'. Finally, the ABSENT hypothesis tries to put forth a direct chemical mechanism behind the apparent synergy and increased association between old age, pre- and coexisting vascular disease, diabetes and AD.

Enhanced Prospects for Drug Delivery and Brain Targeting by the Choroid Plexus–CSF Route

The choroid plexus (CP), i.e., the blood-cerebrospinal fluid barrier (BCSFB) interface, is an epithelial boundary exploitable for drug delivery to brain. Agents transported from blood to lateral ventricles are convected by CSF volume transmission (bulk flow) to many periventricular targets. These include the caudate, hippocampus, specialized circumventricular organs, hypothalamus, and the downstream pia-glia and arachnoid membranes. The CSF circulatory system normally provides micronutrients, neurotrophins, hormones, neuropeptides, and growth factors extensively to neuronal networks. Therefore, drugs directed to CSF can modulate a variety of endocrine, immunologic, and behavioral phenomema; and can help to restore brain interstitial and cellular homeostasis disrupted by disease and trauma. This review integrates information from animal models that demonstrates marked physiologic effects of substances introduced into the ventricular system. It also recapitulates how pharmacologic agents administered into the CSF system prevent disease or enhance the brain's ability to recover from chemical and physical insults. In regard to drug distribution in the CNS, the BCSFB interaction with the blood-brain barrier is discussed. With a view toward translational CSF pharmacotherapy, there are several promising innovations in progress: bone marrow cell infusions, CP encapsulation and transplants, neural stem cell augmentation, phage display of peptide ligands for CP epithelium, CSF gene transfer, regulation of leukocyte and cytokine trafficking at the BCSFB, and the purification of neurotoxic CSF in degenerative states. The progressively increasing pharmacological significance of the CP-CSF nexus is analyzed in light of treating AIDS, multiple sclerosis, stroke, hydrocephalus, and Alzheimer's disease.