Psychiatry Research EG

The diagnosis of definite Alzheimer’s disease (AD) can only be made by postmortem neuropathological confirmation of individuals who had been studied in life and met the criteria for dementia [1]. Clinical AD is still diagnosed by excluding other causes of dementia. A combination of clinical examination with neuroimaging may improve diagnostic accuracy using neuropathology as the standard of comparison. Temporal lope atrophy progresses 10 times faster in AD than in normal aging. Indices of atrophy are statistically related to cognitive performance [2]. Such variables were correlated with the severity of neuropathological changes. Hence, Hentschel and Forstel [3] concluded that hippocampal imaging has proven to be a clinically useful and feasible method for identifying patients with early AD, which is demonstrated by diffusion-weighted imaging (DWI) technique. This technique involves noninvasive functional imaging, that is, processing through high-speed magnetic resonance imaging (MRI), with images acquired in a few seconds or less, thus providing motion-free images. The advent of a high-speed gradient has made DWI an everyday routine scan and has led to its establishment as an Food and Drug Administration-approved clinical screening examination for nearly all neurology examinations today [4]. With the modest but important breakthrough in the treatment of AD, the diagnostic focus has increasingly shifted to the accurate detection of the earliest phase of the illness. The challenge of distinguishing preclinical AD from changes in normal aging or established AD has been recognized during several attempts at clinical classification. Of these attempts, Mayo Clinic’s MCI has received significant attention. However, as not all individuals diagnosed as having MCI will develop AD; hence, there is a need to predict progression reliably [5]. The diagnosis and prognosis of a-MCI has been studied most thoroughly. It is frequently a prodrome to AD, whereas the prognostic significance of other subtypes of MCI is not well understood. Brain imaging studies are not routinely used for the diagnosis of MCI, although imaging techniques are rapidly developing and may prove to be clinically useful in future [6]. The aim of this study was to determine the relationship between the measures of diffusivity of water molecules and clinically diagnosed AD and its prototype a-MCI. Changes in DWI in the right and left cerebral regions of AD were assessed. In addition, the relationship between the severity of cognitive and behavioral manifestations of AD as measured by neuropsychological assessments and the DWI was tested. Determination of such a relationship may help in differentiating between normal aging, MCI, and AD and hence, improving the diagnostic accuracy.