Fig. 2.

Only severely demented AD patients show a significant decrease in CSF levels of cGMP. a Correlation analysis of CSF cGMP levels with the cognitive performance (MMSE score) of all participants showed a significant correlation of CSF cGMP levels and MMSE scores (p = 0.046, Spearman’s rank correlation coefficient). b CSF levels of cGMP of control subjects and AD patients stratified by their MMSE scores (severe AD = MMSE 5–17, moderate AD = MMSE 17–23, mild AD = MMSE 23–27). Only severely demented AD patients show a significant reduction in CSF cGMP levels compared with the control group (p < 0.01, Mann–Whitney U test). c Correlation of CSF cGMP levels with neurodegeneration marker tau showed a significantly negative correlation (p = 0.001, Spearman’s rank correlation coefficient). cGMP cyclic guanosine-3',5'-monophosphate, MMSE mini-mental state examination