NEFL and Mental deterioration: For participants with low NfL concentrations (≤25 pg/mL), those who took part in medium physical activity had 43% slower global cognitive decline (β, –0.025; 95% CI, −0.043 to −0.007) and individuals who participated in high physical activity had 30% slower decline (β, –0.031; 95% CI, −0.048 to −0.014) than did those who participated in low physical activity (β, –0.046; 95% CI, −0.066 to −0.025).