Cognitive dysfunction in patients with interstitial lung disease

To investigate cognitive status in patients with interstitial lung disease (ILD) and its association with lung tissue transcriptomic alterations, and to propose potential lung-brain interaction mechanisms and clinical implications.

We enrolled 45 ILD patients and 45 age-matched controls and compared Mini-Mental State Examination (MMSE) total and subscale scores. Baseline laboratory and pulmonary function characteristics of ILD were summarized. Using lung tissue RNA-seq data from GSE213001 {29 ILD cases [20 idiopathic pulmonary fibrosis (IPF), 9 non-IPF], 14 non-diseased controls [NDC], totaling 139 samples}, we performed PCA, differential expression analysis using the limma-voom framework with the duplicate Correlation function to account for within-donor correlations (threshold |log₂FC| > 1, FDR-adjusted p-value < 0.05), and GO enrichment. We focused on enrichment related to neurodegeneration/cognition and inflammatory pathways, and compared the expression of AD-related genes (PSEN1, PSEN2, BACE1, and MME) between ILD and NDC.

ILD patients showed significantly lower MMSE total scores than healthy controls, with notable declines in attention/calculation and orientation. At the transcriptomic level, PCA clearly separated ILD from NDC, whereas IPF and non-IPF did not form distinct subgroups. Differential analysis identified 1,544 DEGs (1,142 upregulated; 402 downregulated). Enrichment analysis confirmed strong signals for inflammatory and fibrotic pathways. In an exploratory analysis, we also observed enrichment for terms related to nervous system function. The expression trends of several genes previously implicated in neurocognitive contexts, including PSEN1, PSEN2, BACE1, showed a directional concordance with patterns described in neurodegenerative contexts.

This study provides preliminary evidence linking ILD to cognitive impairment on screening and identifies intriguing overlaps between lung tissue transcriptomic alterations and pathways relevant to brain function. These convergent observations lend biological plausibility to, and motivate further investigation of, a lung-brain axis hypothesis in ILD. The findings highlight the need to consider cognitive health in ILD management and warrant validation in longitudinal cohorts with detailed neuropsychological phenotyping.