Establishing Brain Reference Ranges in Indian Population: Comparison with Westerners and Validation for Parkinsonism Differential Diagnosis

Motivation: The human brain varies significantly across ethnicities, yet reference data for the Indian population is lacking. Addressing this gap could enhance the accuracy of brain abnormality quantification. Goal(s): Provide Indian reference ranges and validate them with Indian patients. Approach: We build novel reference ranges from Indian controls, compare them with Western controls, and validate the resulting ranges by analyzing brain atrophy patterns in Indian patients with Parkinsonian syndromes. Results: We found significant differences for 18 out of 55 brain regions between Indian and Western controls. Patient analysis revealed midbrain atrophy in Progressive Supranuclear Palsy and pons atrophy in Multiple System Atrophy, as expected. Impact: We release age-/sex-/ethnicity-specific reference ranges built from Indian and Western controls. We show notable variations highlighting the need for population-specific reference modeling. Additionally, our reference ranges enable the detection of specific atrophy patterns in patients with different Parkinsonian syndromes.