Hippocampal volumes among older Indian adults: Comparison with Alzheimer's disease and mild cognitive impairment.

Background: Hippocampal volume data from India have recently been reported in younger adults. Data in older adults are unknown. The present paper describes hippocampal volume from India among older adults and compares the same with patients having Alzheimer's disease (AD) and mild cognitive impairment (MCI).

Materials And Methods: A total of 32 cognitively normal subjects, 20 patients with AD, and 13 patients with MCI were enrolled. Patients were evaluated for the diagnosis of AD/MCI using the National Institute of Neurological and Communicative Disorders and Stroke and the Related Disorders Association criteria and the Clinical Dementia Rating (CDR) Scale (score = 0.5), respectively. Hippocampal volume was measured using magnetic resonance imaging (MRI) machine by manual segmentation (Megnatom Symphony 1.5T scanner) three-dimensional (3D) sequences.

Results: Age and duration of illness in the MCI group were 70.6 ± 8.6 years and 1.9 ± 0.9 years, respectively. In the AD group, age and duration of illness were 72 ± 8.1 years and 3.1 ± 2.2 years, respectively. In cognitively normal subjects, the age range was 45-88 years (66.9 ± 10.32) years. Mean mini-mental status examination (MMSE) score of healthy subjects was 28.28 ± 1.33. In the MCI group, MMSE was 27.05 ± 1.79. In the AD group, MMSE was 13.32 ± 5.6. In the healthy group, the hippocampal volume was 2.73 ± 0.53 cm(3) on the left side and 2.77 ± 0.6 cm(3) on the right side. Likewise, in MCI, the volume on the left side was 2.35 ± 0.42 cm(3) and the volume on the right side was 2.36 ± 0.38 cm(3). Similarly, in the AD group, the volume on the right side was 1.64 ± 0.55 cm(3) and on the left side it was 1.59 ± 0.55 cm(3). Post hoc analysis using Tukey's honestly significant difference (HSD) showed, using analysis of variance (ANOVA) that there was a statistically significant difference between healthy and AD (P ≤ 0.01), and between healthy and MCI (P ≤ 0.01) subjects. There was a correlation between MMSE score and hippocampal volume in the AD group.

Conclusion: The volume of the hippocampus in older Indian adults was 2.77 ± 0. 6 cm(3) on the right side and 2.73 ± 0.52 cm(3) on the left side. There was a significant hippocampal volume loss in MCI/AD compared to cognitively normal subjects.