Phenylephrine and pilocarpine eye drop test for dementia with Lewy bodies and Alzheimer's disease

Ophthalmic manifestations of dementing disorders

PURPOSE OF REVIEW

Dementia is a term for loss of memory, language, problem-solving, and other thinking abilities, which significantly interferes with daily life. Certain dementing conditions may also affect visual function. The eye is an accessible window to the brain that can provide valuable information for the early diagnosis of people who suffer from Alzheimer's disease, Parkinson's disease, dementia with Lewy bodies as well as from more rare causes of dementias, such as Creutzfeldt-Jacob and Huntington's diseases. Herein, we present the ocular manifestations of neurocognitive disorders focusing on the neuro-ophthalmic ones and further discuss potential ocular biomarkers that could help in early detection of these disorders.

RECENT FINDINGS

Ophthalmic examination along with the recent developments in in-vivo testing have provided a strong foundation of useful knowledge about brain disorder in neurodegenerative diseases without the need for invasive studies. Currently, a number of visual measures, such as visual acuity, contrast sensitivity, pupil response, and saccades in addition to various ophthalmic tests, such as electroretinogram, visual evoked potential, optical coherence tomography (OCT), and OCT-angiography have been widely used and evaluated as potential biomarkers for different stages of dementia.

SUMMARY

Ophthalmologic and neuro-ophthalmic evaluation is evolving as an important part of the early diagnosis and management of people with dementia. A particular focus on ocular biomarkers in dementing illnesses has arisen over the past few years and there are several promising measures and imaging tools that have been proposed as potential biomarkers for these diseases.

Drug Repurposing for Alzheimer's Disease Based on Protein-Protein Interaction Network

Alzheimer's disease (AD) is known as a critical neurodegenerative disorder. It worsens as symptoms concerning dementia grow severe over the years. Due to the globalization of Alzheimer's disease, its prevention and treatment are vital. This study proposes a method to extract substantial gene complexes and then introduces potential drugs in Alzheimer's disease. To this end, a protein-protein interaction (PPI) network was utilized to extract five meaningful gene complexes functionally interconnected. An enrichment analysis to introduce the most important biological processes and pathways was accomplished on the obtained genes. The next step is extracting the drugs related to AD and introducing some new drugs which may be helpful for this disease. Finally, a complete network including all the genes associated with each gene complex group and genes' target drug was illustrated. For validating the proposed potential drugs, Connectivity Map (CMAP) analysis was accomplished to determine target genes that are up- or downregulated by proposed drugs. Medical studies and publications were analyzed thoroughly to introduce AD-related drugs. This analysis proves the accuracy of the proposed method in this study. Then, new drugs were introduced that can be experimentally examined as future work. Raloxifene and gentian violet are two new drugs, which have not been introduced as AD-related drugs in previous scientific and medical studies, recommended by the method of this study. Besides the primary goal, five bipartite networks representing the genes of each group and their target miRNAs were constructed to introduce target miRNAs.

The Pupil Diameter as a Possible Indicator of Neurodegenerative Diseases and Response to Acetylcholinesterase Inhibitors Therapy: In-Depth Measurements Following Topical Administration of Tropicamide and Pilocarpine

BACKGROUND

The aim of this study is to assess whether pupillary modifications following ocular anticholinergic and cholinergic drugs can identify subjects with neurodegenerative diseases from early stages.

METHODS

51 subjects were divided into 3 groups, according to different neurodegenerative diseases, and compared with a control group of 10 patients. Pupil diameter has been measured at different times after topical administration of tropicamide 0.01% in the right eye. Then, topical administration of pilocarpine 0.06% has been performed, followed by pupillary constriction measurement. Pupillary response rates were stratified according to acetylcholinesterase inhibitors intake.

RESULTS

Observed mydriasis and pupillary constriction was similar in all study groups at all evaluation times. Patients without acetylcholinesterase inhibitors intake presented greater mydriasis.

CONCLUSIONS

Although it was not possible to observe significant differences among groups in terms of pupillary response, the analysis of pupillary features may become an useful tool to detect efficacy of acetylcholinesterase inhibitors.

Visual system manifestations of Alzheimer's disease

Alzheimer's disease (AD) is an increasingly common disease with massive personal and economic costs. While it has long been known that AD impacts the visual system, there has recently been an increased focus on understanding both pathophysiological mechanisms that may be shared between the eye and brain and how related biomarkers could be useful for AD diagnosis. Here, were review pertinent cellular and molecular mechanisms of AD pathophysiology, the presence of AD pathology in the visual system, associated functional changes, and potential development of diagnostic tools based on the visual system. Additionally, we discuss links between AD and visual disorders, including possible pathophysiological mechanisms and their relevance for improving our understanding of AD.

Autonomic dysfunction in neurodegenerative dementias

Syncope associated to orthostatic hypotension (OH), urinary incontinence and constipation is common symptoms in demented patients, mainly in dementia with Lewy bodies (DLB) and in Parkinson's disease dementia (PDD). Alzheimer's disease (AD) and fronto temporal lobar degeneration (FTLD) show less autonomic dysfunction. Urinary symptoms are a prominent component of normal pressure hydrocephalus (NPH). There are non invasive tests including standard cardiovascular tests, 123 I-metaiodobenzylguanide (MIBG) cardiac scintigraphy, urodynamic tests, gastrointestinal motility studies, sweating reflexes and pupillary responses that assess autonomic dysfunction in these patients. The study of autonomic symptoms and abnormal tests in patients with dementia is useful to prevent morbidity due falls, severe constipation and to avoid side effects of drugs that interfere with autonomic function.

Diagnostic performance of myocardial innervation imaging using MIBG scintigraphy in differential diagnosis between dementia with lewy bodies and other dementias: a systematic review and a meta-analysis

BACKGROUND AND PURPOSE

This study was designed to review the diagnostic performance of myocardial innervation imaging using iodine-123-metaiodobenzylguanidine (MIBG) scintigraphy in differential diagnosis between dementia with Lewy bodies (DLB) and other dementias.

METHODS

A comprehensive computer literature search of studies published through May 2010 regarding MIBG scintigraphy in patients with DLB was performed in PubMed/MEDLINE and Embase databases. Only studies in which MIBG scintigraphy was performed for differential diagnosis between DLB and other dementias were selected. Pooled sensitivity and specificity of MIBG scintigraphy were presented with a 95% confidence interval (CI). The area under the ROC curve was calculated to measure the accuracy of MIBG scintigraphy in differential diagnosis between Lewy body diseases and other dementias.

RESULTS

Ultimately, we identified 8 studies comprising a total of 346 patients with dementia (152 patients with DLB and 194 patients with other dementias). The pooled sensitivity of MIBG scintigraphy in detection of DLB was 98% (95% CI, 94-100%); the pooled specificity of MIBG scintigraphy in differential diagnosis between DLB and other dementias was 94% (95% CI, 90-97%). The area under the ROC curve was .99.

CONCLUSIONS

Myocardial innervation imaging with MIBG scintigraphy demonstrated high pooled sensitivity and specificity in patients with suspected DLB. MIBG scintigraphy is an accurate test for differential diagnosis between DLB and other dementias.

Alzheimer's disease: visual system review

BACKGROUND

Ten million baby boomers in the United States will get Alzheimer's disease. Optometrists can benefit from understanding the impact the Alzheimer's disease process has on the visual system. This can result in more effective management of the condition and in more effective communication with members of the Alzheimer's disease multidisciplinary team.

METHODS

This is a review of the literature but by no means a completely exhaustive review. Alzheimer's disease is a complex disease. A rapidly expanding body of knowledge covers multiple disciplines.

RESULTS

The visual system shows deficits early in the degenerative process of Alzheimer's disease. Biomarkers through the visual system such as nerve fiber deficits, lens opacities, and functional losses in the magnocellular pathway, such as contrast sensitivity and temporal processing, may prove to not only help detect Alzheimer's disease early but also detect it before there are the classic cognitive and memory losses.

CONCLUSIONS

The effects of Alzheimer's disease are devastating. Optometrists, as primary care clinicians, can make critical contributions in the diagnosis, treatment, and management of this neurodegenerative disease.

Current and future uses of neuroimaging for cognitively impaired patients

Technological advances have led to greater use of both structural and functional brain imaging to assist with the diagnosis of dementia for the increasing numbers of people with cognitive decline as they age. In current clinical practice, structural imaging (CT or MRI) is used to identify space-occupying lesions and stroke. Functional methods, such as PET scanning of glucose metabolism, could be used to differentiate Alzheimer's disease from frontotemporal dementia, which helps to guide clinicians in symptomatic treatment strategies. New neuroimaging methods that are currently being developed can measure specific neurotransmitter systems, amyloid plaque and tau tangle concentrations, and neuronal integrity and connectivity. Successful co-development of neuroimaging surrogate markers and preventive treatments might eventually lead to so-called brain-check scans for determining risk of cognitive decline, so that physicians can administer disease-modifying medications, vaccines, or other interventions to avoid future cognitive losses and to delay onset of disease.