The mean ADA activity in TBM patients was 14.31 ± 3.87 (2.99–26.94), significantly higher than the non-TBM infectious meningitis group, 9.25 ± 2.14 (4.99–13.96); P < 0.0001, and also higher than the non-infectious neurological disorders group, 2.71 ± 1.96 (0.00–7.68); P < 0.0001. Here, ADA is linked to meningeal tuberculosis.