Background: Suicidal ideation is thought to be of high risk for attempts and behaviours. Researches have suggested that depressive symptoms and impulsiveness can affect suicidal ideation, attempts and behaviours independently. But how they work together in influencing suicidal ideation remains unclear. This study is aiming to investigate the reciprocal associations among impulsiveness, depressive symptoms, and suicidal ideation and to confirm the mediating effect of depressive symptoms on

more »

... iveness and suicidal ideation through cross-sectional and longitudinal analyses.Methods: The Self-rating Depression Scale (SDS), Barratt Impulsiveness Scale 11th version (BIS-11) and Self-rating Idea of Suicide Scale (SIOSS) were applied, as well as a list of demographic information. Multilinear regression and parallel process latent growth curve models were applied to conduct cross-sectional and longitudinal analyses, respectively.Results: (1) Participants with suicidal ideation scored higher in depressive symptoms and impulsiveness than those without suicidal ideation (P<10-5). (2) The three variables and the three dimensions of impulsiveness were significantly reciprocally correlated with each other (P<0.01). (3) For the impulsiveness total score, non-planning, motor and attention, the multilinear regression models fit well (adjusted R2>0.3, SRMR<0.05). Their indirect effects on suicidal ideation through depressive symptoms were all statistically significant (BIS-SDS-SIOSS, indirect effect coefficient=0.557, P<0.001; non-planning-SDS-SIOSS, indirect effect coefficient=0.480, P<0.001; motor-SDS-SIOSS, indirect effect coefficient=0.486, P<0.001; attention-SDS-SIOSS, indirect effect coefficient=0.504, P<0.001). (4) Four parallel process latent growth curve models fit well (RMSEA<0.05). The total indirect effect of impulsiveness on the growth rate of suicidal ideation through the initial level and growth rate of depressive symptoms was significant (indirect effect coefficient=-0.450, P=0.001). The indirect effects of non-planning and attention impulsiveness were -0.336 (P=0.005) and -0.314 (P=0.002), respectively. However, the indirect effect of motor function on the growth rate of suicidal ideation was not significant (coefficient=-0.379, P=0.067).Conclusions: This study mainly revealed that individuals with impulsive personalities might be at higher risk for and experience more rapid changes in suicidal ideation. The effects were indirect and mediated by depressive symptoms. This implies that impulsive personality with depressive symptoms is critical for suicide prevention and needs more attention.