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iConcept Journal of Emerging Issues in Medical Diagnosis and Treatment
Title
iConcept Journal of Emerging Issues in Medical Diagnosis and Treatment
Editor
Eugenia Giannopoulou
ISSN
2309-3528
Publisher
iConcept Press

iConcept Journal of Emerging Issues in Medical Diagnosis and Treatment

Biomarkers in Alzheimer’s Disease: A review

by Meena Chintamaneni and Manju Bhaskar

Volume: 2 (2013); Issue: 11

Abstract

Alzheimer’s disease is the most common form of dementia affecting millions of individuals worldwide. With increasing life expectancy dementia is a growing socioeconomic and medical problem. Many factors have been linked to the incidence of AD, including age, gender (females are more likely to be affected), genetic factors, head injury and Down’s syndrome. It is estimated that, by 2050, the number of people aged 80 years or older will approach 370 million worldwide and that 50 % of those aged 85 years or older will be afflicted with AD. Intracellular neurofibrillary tangles (NFT) containing hyperphosphorylated tau protein and apolipoprotein E and extra cellular senile (neuritic) plaques containing many proteins, including β-amyloid (Aβ), α-synuclein, ubiquitin, apolipoprotein E, presenilins and alpha antichymotrypsin, are considered hallmarks of AD. Lewy bodies are present in the brains of about 60% of AD cases. The pathogenic process of AD probably starts decades before clinical onset of the disease. During mild cognitive impairment (MCI), there is a gradual neuronal loss. The first symptoms, most often impaired episodic memory, appear at a certain threshold in MCI. The enzymes like acetylcholinesterase, chitinase, β-secretase also serve as biomarkers for Alzheimer’s disease. All individuals with MCI do not progress to AD, and the ability to predict which ones would see such a progression greatly facilitate the diagnosis of AD over normal ageing-associated cognitive impairment as well as other forms of dementia. The discovery of clinically useful and robust biomarkers for AD and pre-AD are necessary for clinicians to accurately diagnose AD or predict conversion of a preclinical state of AD. It is currently diagnosed only via clinical assessments and confirmed by postmortem brain pathology. The development of validated biomarkers for Alzheimer’s disease is essential to improve diagnosis and accelerate the development of new therapies. Biochemical and neuroimaging markers could facilitate diagnosis, predict AD progression from a pre-AD state of mild cognitive impairment (MCI), and be used to monitor efficacies of disease-modifying therapies. Cerebrospinal fluid (CSF) levels of Aβ40, Aβ42, total tau, and phosphorylated tau have diagnostic values in AD. Measurements of the above CSF markers in combination are useful in predicting the risk of progression from MCI to AD. These biomarkers along with clinical assessment, neuropsychological testing, and neuroimaging could achieve a much higher diagnostic accuracy for AD and related disorders in the future. Treatment strategies might be most effective before pathological changes spread throughout the brain. Thus, an early diagnosis with reliable biomarkers is essential to distinguish between AD, mild cognitive impairment (MCI), and other dementia types. New potential biomarkers are emerging, and CSF or plasma marker profiles may eventually become part of the clinician’s toolkit for accurate AD diagnosis and management.

Author Details

Meena Chintamaneni
Department of Pharmacology, NarseeMonjee Institute of Management Studies (NMIMS), Vile Parle, India, India
Manju Bhaskar
Department of Pharmacology, NarseeMonjee Institute of Management Studies (NMIMS), Vile Parle, India, India

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