Profiles of Alzheimer's disease-related pathology in an aging urban population sample in India

Abstract

Systematic studies on Alzheimer's disease (AD)-related pathology that complement clinical and epidemiological data on dementia from low and middle income countries are rare. We report the first large study on AD-related pathology in autopsy service-derived brains from an urban center in India, a low/middle income country, and compare findings with a similar sample from New York. Amyloid-β plaques and neurofibrillary tangles were assessed in 91 brain specimens derived from hospital autopsy cases from Mumbai, India (age 60+ years; mean age 71.1 years, ± 8.3 SD; range 60-107 years) and compared with identically examined age-matched sample obtained in New York. These cases had no known clinical history of dementia. Our study showed that in comparison with the New York sample, the mean brain weight of the Mumbai sample was lower (p = 0.013) and mean diffuse plaque density was higher (p = 0.019), while differences in mean density and counts of neurofibrillary tangles and neuritic plaques were not statistically significant (p > 0.05). Our findings indicate that the burden of AD-related pathology was approximately equivalent in Mumbai and New York samples, which is at variance with expected lower AD-related lesion burden based on the clinical/epidemiological studies suggesting lower prevalence of AD in India.

Fig. 1

Histological images of AD-related lesions in neocortex: (A) modified Bielschowsky's silver stain, (B) Aβ immunohistochemistry demonstrating amyloid plaques and (C) hyperphosphorylated tau immunohistochemistry for neurofibrillary tangles. Senile plaques (SP, large arrow); diffuse plaque (DP, small arrow), and neurofibrillary tangles (NFT, arrowheads) (bar = 150 μm).

Fig. 2

Histological images of AD-related lesions in the layer CA1 of the hippocampus by modified Bielschowsky's silver stain (A), Aβ immunohistochemistry demonstrating amyloid plaques (B) and hyperphosphorylated tau immunohistochemistry for neurofibrillary tangles (C) (bar = 120 μm).

Fig. 3

Histological images of AD-related pathology in the entorhinal cortex by modified Bielschowsky's silver stain (A), Aβ immunohistochemistry demonstrating amyloid plaques (B) and hyperphosphorylated tau immunohistochemistry for neurofibrillary tangles (C). Senile plaques (SP, large arrow); diffuse plaque (DP, small arrow), and neurofibrillary tangles (NFT, arrowheads) (bar = 120 μm).

Fig. 4

Comparison of AD related pathology in 91 age-matched cases of the Mumbai and New York samples. SP, neuritic/amyloid core plaques; DP, diffuse amyloid plaques; NFT, neurofibrillary tangles; NC, neocortex; Hip, hippocampus; EC, entorhinal cortex.