Caudate nucleus atrophy as a neuroimaging feature of mild cognitive impairment induced by occupational aluminum exposure.

Occupational aluminum (Al) exposure is linked to mild cognitive impairment (MCI), yet its neuroanatomical mechanisms remain unclear. We investigated gray matter volume (GMV) alterations specifically associated with Al-induced MCI. This study enrolled 86 participants: 30 Al-exposed MCI (Al-MCI), 26 Al-exposed cognitively normal (Al-HC), and 30 non-exposed controls (Non-Al-HC). Structural MRI quantified whole-brain GMV. Plasma Al concentrations, Montreal Cognitive Assessment (MoCA), the Rey Auditory Verbal Learning Test (AVLT), and the Trail Making Test (TMT) were assessed in Al-exposed individuals. Intergroup GMV differences were analyzed via ANCOVA. Partial correlations and mediation analyses explored cognition-GMV relationships. We found that Al-MCI and Al-HC showed comparable plasma Al concentrations (42.74 ± 26.00 vs. 32.52 ± 30.86 µg/L, p = 0.184). A graded pattern of bilateral caudate nucleus (CAU) atrophy was observed: most severe atrophy in the Al-MCI group, intermediate atrophy in the Al-HC group, and the largest volumes in the Non-Al-HC group (p < 0.05 for all pairwise comparisons). In Al-exposed individuals, left CAU volume correlated positively with abstraction (r = 0.294, p = 0.028), language (r = 0.321, p = 0.016), and AVLT-immediate recall (r = 0.289, p = 0.030). Right CAU volume correlated negatively with TMT-A error responses (r=-0.306, p = 0.022). In conclusions, CAU atrophy was significantly associated with cognitive decline and may represent a specific neuroimaging feature of occupational Al-induced MCI.