The demographics of aging suggest a great need for an early diagnosis of dementia and for the development of preventive strategies. Neurodegeneration in Alzheimer's disease (AD) is estimated to start even 20-30 years before clinical onset, and the identification of biological markers for pre-clinical and early diagnosis is the principal aim of research studies in the field.It is still difficult to make diagnosis in the early disease stages. At the beginning the patient might have a deficit limited to memory or to another single cognitive domain, without any disorder of instrumental and daily activities. The cognitive impairment then might proceed to a degree that allows the diagnosis of dementia. The transitional state between normal ageing and mild dementia has been recently indicated by the term Mild Cognitive Impairment (MCI).In the last few years, a wide range of studies addressed this topic. Clinically, within the group of MCI subjects, two separate subgroups have been described, those rapidly converting to AD (MCI converters), in whom MCI represents the early stage of an ongoing AD-related process, and those who remain stable (MCI non-converters), in whom the isolated cognitive deficits represent a different condition without an increased risk to develop dementia at short follow-up.In this line, reliable markers for early AD detection could be useful both for prognosis, and for identifying a potential target for therapeutic intervention, since treatments are emerging which rather than reversing structural damage are likely to slow or halt the disease process.While currently no routine diagnostic test confirms AD presence, functional neuroimaging techniques represent an important tool in biological neurology. The challenge for neuroimaging methods is to achieve high specificity and sensitivity in early disease stages and at single subject level. Functional imaging, in particular, has the potential to detect very early brain dysfunction even before clear-cut neuropsychological deficits emerge. Predicting progression to AD in cases of MCI and supporting diagnosis and differential diagnosis of dementia are the outmost important goals.The implications are the identification of minimally symptom-matic patients that could benefit from treatment strategies, as well as the monitoring of treatment response and the therapeutic decal-eration of the disease.This chapter highlights recent cross-sectional and longitudinal neuroimaging studies in the attempt to put into perspective their value in diagnosing AD-like changes, particularly at an early stage, providing diagnostic and prognostic specificity.There is now considerable evidence supporting that early diagnosis is feasible through a multimodal approach, including also a combination of multiple imaging modalities.
|Title of host publication||Alzheimer's Diagnosis|
|Publisher||Nova Science Publishers, Inc.|
|Number of pages||51|
|Publication status||Published - 2011|
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