Serum 5-hydroxytryptamine levels as biomarkers for motor dysfunction and depression in Parkinson’s disease patients

Figure 1 Combined effects of dyskinesia and depression on serum 5-hydroxytryptamine levels: Four-group analysis. This figure demonstrates a stepwise decline in serum 5-hydroxytryptamine levels across four patient subgroups stratified by the presence of dyskinesia and depression. Patients without either complication had the highest 5-hydroxytryptamine levels (215.7 ng/mL), followed by those with dyskinesia alone (178.9 ng/mL), depression alone (156.8 ng/mL), and both complications showing the lowest levels (122.4 ng/mL). ^aP < 0.001. 5-HT: 5-hydroxytryptamine.