Exosomal mtDNA profiles enable differential diagnosis of alzheimer’s disease across independent cohorts

Mitochondrial DNA (mtDNA) has emerged as a promising biomarker for Alzheimer’s disease (AD), but the role of plasma-derived extracellular vesicle (EV) mtDNA in aiding differential diagnosis remains to be further elucidated. In this study, we evaluated mtDNA from plasma-derived EVs as potential biomarkers to distinguish AD from other non-AD dementias, including vascular dementia (VaD), dementia with Lewy bodies (DLB), Parkinson’s disease dementia (PDD), and chronic traumatic encephalopathy (CTE). Across two independent cohorts comprising 168 healthy controls, 262 AD patients, and 312 non-AD dementia patients, we quantified the EV-associated mtDNA regions ND1 , COX3 , and DLOOP . Copy numbers of all three markers were significantly elevated in AD patients relative to both control and non-AD groups. Although their standalone diagnostic performance for AD was modest, mtDNA markers demonstrated strong discriminatory power in differentiating AD from other dementia subtypes, with composite area under the curves reaching 0.92 and 0.97 in training and validation sets, respectively. Correlation analyses further revealed strong associations between mtDNA levels and established AD-related biomarkers such as phosphorylated Tau217, GFAP, and the Aβ42/40 ratio. These findings suggest that EV mtDNA signatures—particularly ND1 , COX3 , and DLOOP —hold significant promise as differential diagnostic biomarkers, offering added value in distinguishing AD from other forms of dementia rather than serving as standalone diagnostic tools.