In this cross-sectional study on a large sample of 10,015 students, we found a strong association between PPS in childhood and adolescence and suicidal thoughts in young adults. Lower levels of PPS were associated with a higher frequency of both occasional and frequent suicidal thoughts. Thus, a total lack of PPS was associated with more than 4-fold increased risk of occasional suicidal thoughts (aOR, 4.55; 95% CI: 2.97–6.99) and nearly 9-fold increased risk of frequent suicidal thoughts (aOR, 8.58; 95% CI: 4.62–15.96). In all models, we observed a negative association between the level of PPS and the frequency of suicidal thoughts. Sensitivity analyses modifying adjustment and multiple imputation modeling provided consistent results.

Few studies have described the association between PPS and suicidal thoughts in young adults, and most did not control for confounding factors related to the family environment. In one study that included 5183 Chinese students, suicidal ideation was associated with poor family structures and relationships or improper parenting styles [24]. In another study that included 188 African American students, strong family support was associated with a lower incidence of suicide ideation [25]. Similarly, in a Taiwanese study that included 2919 college students, a positive linear trend was observed between increased suicidal tendency and a parenting style with low affection [26]. In a younger age range (adolescents 12 to 18 years old), it was shown that inadequate social and family support increased the risk of suicide or suicidal ideation [27,28,29,30,31]. Similarly, a cross-sectional study that included 448 adolescents aged 13 to 17 years measured PPS with the Perceived Social Support from Family Scale. In that study, each one point increase in PPS was associated with a 54% lower frequency in suicidal plans [32]. Compared to the present study, all those previous studies were more focused on current parental support, in addition to other social determinants. However, a longitudinal study conducted among a large sample of adolescents showed conflicting results. Parental support was predictive of lower levels of depression but was not significantly associated with the outcomes related to suicidal behaviors [33].

The present study had some important strengths, including the size of the sample, the strength of the associations, the PPS-dose-dependent pattern, the consistency of our results with previous studies, and the large number of variables collected and adjusted for in the multivariable models. Furthermore, when we performed multiple imputation for non-response data and the sensitivity analysis, we found consistent results. However, there were also some limitations in this study. First, it was a cross-sectional analysis; therefore, we could not strictly separate the timing of exposure, outcome, and covariates. Moreover, no causality could be inferred between PPS and suicidal ideation. Second, only brief and succinct measures could be done in large sample studies and perceived parental support as well as suicidal ideation were assessed with only one item. This is a limitation that has to be taken into account when interpreting our results. However, the prevalence of suicidal thoughts found in our study fall within the range reported by the main studies on the subject [4,5,6, 8] which was somehow reassuring. Third, the voluntary participation of students may have introduced a self-selection bias, although it is difficult to see how this potential bias could have influenced the observed associations. Fourth, the information was self-reported, which could lead to an information bias, particularly if participants under-reported the frequency of suicidal thoughts or the presence of a personal and/or family history, due to considerations of social acceptability. Again, this under-reporting would be expected to have a low impact on the associations observed. Fifth, there is an over-representation of women in our sample compared to the 56% of female students in France. However, we tested interactions with gender for the main analyses and none was significant. Further, in stratified analyses, aOR did not differ significantly between males and females and the confidence intervals were largely overlapping (data not shown). Finally, although we had information on confounding factors, we could not rule out the influence of residual or unmeasured confounding factors, due to the complexity of the suicidal thought process. In addition, because our predictor variable was PPS, a recall bias might have led to an overestimation of the associations between support and suicidal ideation. However, our findings on the differential roles that PPS played for students with and without a history of depression suggested that a recall bias might have had limited effect. Indeed, we postulated that, if recall bias was a major source of influence, the association between low support and suicidal thoughts would be stronger in students with a history of depression compared to those without. Instead, we found the reverse; students without a history of depression were more likely to report suicidal thoughts, when they also reported low parental support during childhood and adolescence.

We found that our estimation of the risk associated with PPS was higher than previous estimated risks of other variables known to be associated with suicidal ideation, such as parental divorce [34, 35] or parental death [36, 37]. We also noted that the specific role of low PPS could not be distinguished from the roles of other negative parenting practices, such as abuse or neglect (not measured in our study). However, our associations remained significant after controlling for other negative childhood events, such as parental death or divorce.

The association between PPS and suicidal thoughts could reflect a familial aggregation of suicidal thoughts and mood disorders. Contributors to his type of aggregation might be unknown psycho-social, clinical, or biological factors, including genetic factors [38]; for example, parents that provide low support might be experiencing depression [39].

Our results in young adults, if confirmed by other studies, could eventually lead to the development of intervention programs for families at an early stage of life and thus be a prerequisite for more targeted, less costly and more effective prevention interventions [40]. In adolescents, such programs have yielded promising results to decrease the incidence of suicidal thoughts in young adults after an intervention started in adolescence [41, 42]. These interventions, aimed primarily at building parenting support and supervision capacities, are strategies developed by the CDC in suicide prevention [43]. Other programs such as attachment-based family therapy [44] aim to transform the quality of adolescent-parent attachment in order to provide the adolescent with a safer relationship that can support him during difficult times and crises related to suicidal thoughts and behaviors.

Regardless of the subjectivity of the PPS variable or the etiology of suicidal thoughts, evaluating PPS could be useful in assessments of suicidal risk in young adults. Given that PPS is a relatively neutral, non-intrusive variable, health professionals can readily assess PPS to improve suicide risk screening. Our findings indicated that PPS could be a particularly important marker, because the association between PPS and suicidal ideation was stronger in the absence than in the presence of a personal history of attempted suicide or depression. This is remarkable, because a personal history of attempted suicide or depression is an important marker of suicidal risk. Our findings highlighted the importance of interventions that aim to screen for and correct risky situations that children might face at home.

To summarize, our results indicated that a low PPS in childhood and adolescence was strongly associated with frequent suicidal thoughts in young adults. This issue should be systematically addressed in further clinical studies on suicidal risk in young people and, if confirmed, it could be considered in routine care. Longitudinal studies should assess the ability of PPS to predict the risk of suicide attempts and suicide.