Clinical and Biochemical Predictors of Hippocampal Atrophy in Alzheimera？？s Disease

Aim: Hippocampus is an important brain structure responsible for learning and episodic memory. It is also a plastic and vulnerable structure damaged by a variety of factors. Incidentally, it is among the first and the most severely affected structure that undergoes atrophy in Alzheimera？？s disease (AD), the leading cause of dementia worldwide. Though considered neurodegenerative; the role of vascular and other associated factors causing hippocampal atrophy in AD is under investigation. In the present study; an attempt was made to explore the effect of presence of various clinical and biochemical predictors on the hippocampal volumes in patients with AD. Methods: We screened 280 subjects coming to the Department of Neurology of a Tertiary Care Hospital with memory/and or cognitive complaints starting from July 2012 to December 2015 and enrolled 144 subjects. Those who met the diagnostic Criteria for the diagnosis of probable AD (National Institute of Neurological and Communicative Disorders and Stroke, Alzheimera？？s disease related Disease Association criteria (NINCDS-ARDA), were recruited for the present study. Selected patients were segregated into AD-associated comorbidities or biochemical alterations in AD e.g. AD-diabetes, AD-hypertension, AD-depression, AD-seizures categories or AD-hyperhomocysteinemia, AD-hypercortisolemia, AD-vitamin D3 and AD-vitamin B12 deficient patients groups. Selected patients underwent Magnetic Resonance Imaging of the Brain (MRI Brain) and T1 weighted images in a plane perpendicular to long axis of hippocampus were obtained. Hippocampal volumes were measured manually using a standard protocol. The comparison of hippocampal volumes was done among the groups e.g. with the cognitively normal individuals and those patients of AD with or without vascular and non vascular risk factors. Results: Out of 280 patients screened, 144 met the diagnostic criteria for AD. A total of 8 patients (n=64) per predictor group were selected in the predictor-stratified group. There was a statistically significant difference between the hippocampal volumes of the cognitively normal elderly (n=30), those patients with AD without vascular or other risk factors (n=20), and patients with cumulative risk factors (n=30) [p-value<0.05]. Hippocampal volumes of those with atleast one of the biochemical/vascular or non vascular risk factor for hippocampal atrophy was compared with the patients without risk factors and there was a statistically significant difference between these groups (p-value<0.05). There was a moderately strong correlation between