Aims Cardiac troponin T (cTnT), measured with a high-sensitivity (hs) assay, is associated with cognitive decline, but the underlying mechanism is unknown. We investigated the association of hs-cTnT with cognitive function and decline, and studied whether this association was independent of cardiovascular diseases or risk factors, and N-terminal pro-brain natriuretic peptide (NT-proBNP). Methods and results We studied 5407 participants (mean age 75.31 years) from the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER), who all had cardiovascular diseases or risk factors thereof. Participants with pre-existent advanced clinical heart failure were excluded. Hs-cTnT and NT-proBNP obtained after 6 months of follow-up were related with cognitive function, tested repeatedly during a mean follow-up of 3.2 years. Participants with higher hs-cTnT performed worse at baseline on Stroop test (mean baseline score (standard error (SE)) lowest vs highest third 65.91 (1.16) vs 69.40 (1.10) seconds, p < 0.001), Letter-Digit Coding test (23.35 (0.32) vs 22.40 (0.31) digits coded, p < 0.001), immediate Picture-Word Learning test (9.45 (0.09) vs 9.31 (0.08) pictures remembered, p = 0.002) and delayed Picture-Word Learning test (10.33 (0.12) vs 10.10 (0.12) pictures remembered, p = 0.013). Furthermore, participants with higher hs-cTnT had steeper decline on Stroop test (mean annual change (SE) lowest vs highest third 0.34 (0.12) vs 1.06 (0.12) seconds, p = 0.013), Letter-Digit Coding test (-0.29 (0.03) vs -0.46 (0.03) digits coded, p < 0.001), immediate Picture-Word Learning test (0.01 (0.01) vs -0.06 (0.01) pictures remembered, p < 0.001) and delayed Picture-Word Learning test (-0.03 (0.01) vs -0.12 (0.02) pictures remembered, p = 0.001). Associations were independent of cardiovascular diseases risk factors or Apolipoprotein E genotype. Further adjusting for NT-proBNP levels revealed the same results. Conclusions Higher levels of hs-cTnT associate with worse cognitive function and steeper cognitive decline in older adults independent of cardiovascular diseases, risk factors and NT-proBNP.