Childhood anxiety/withdrawal

Similar rates of item endorsement were found across the male and female subsamples, and the NCT detected no statistically significant difference between the male and female childhood network models. It is noted that the NCT is conservative with regard to identifying significant group network differences, so this result should not be interpreted as firm evidence of no true sex difference (Van Borkulo, Reference Van Borkulo2015). However, the strong similarity (r_p = 0.87) between the networks estimated from the male and female subsamples suggests a childhood anxiety/withdrawal causal system may function through similar pathways in both males and females. While some evidence suggests that there are sex differences in anxious childhood behaviour (Anderson et al., Reference Anderson, Williams, McGee and Silva1987; Bender et al., Reference Bender, Reinholdt-Dunne, Esbjørn and Pons2012; Lewinsohn et al., Reference Lewinsohn, Gotlib, Lewinsohn, Seeley and Allen1998), the present findings tend to fall in line with the view that notable sex differences in anxious behaviour emerge later, during puberty (Hayward & Sanborn, Reference Hayward and Sanborn2002; Pine & Fox, Reference Pine and Fox2015).

The spinglass community-detection algorithm retrieved a four-community solution for both the male and female subsamples. Four items changed community between subsamples. As the spinglass algorithm allows each node to inhabit only one community, the structure identified by the algorithm should be interpreted only as an aid. Much ‘bridging’ (Jones, Ma, & McNally, Reference Jones, Ma and McNally2019) was observed between communities, indicating that the groupings may be malleable. For instance, the items overly sensitive (AW11) and overly serious or sad (AW12) appeared to bridge two communities (social-emotional and response to authority); small changes in edge weights between the male and female subsamples thus resulted in them being grouped into the social-emotional community in the male subsample and the response to authority community for the female subsample. On face value, these two items may be better characterised as social-emotional, but the network structures indicate they may influence anxious/withdrawn responses towards authority figures.

Network outcome analyses

Previous research on the CHDS cohort has found that childhood anxiety/withdrawal, when modelled as a unidimensional variable, predicts later AD (Goodwin et al., Reference Goodwin, Fergusson and Horwood2004; Jakobsen et al., Reference Jakobsen, Horwood and Fergusson2012). The present findings add nuance to this established relationship by demonstrating that not all items measuring childhood anxiety/withdrawal procure the same type or degree of risk.

Childhood anxiety/withdrawal items formed a total of 16 positive edges and one negative edge with outcome AD variables across the four NOA models. Further, seven of these edges were considered robust, as they were retrieved in >70% of bootstrapped models using both the GGM and MGM estimation procedures. It is important to note that edges which did not meet the defined robustness criteria are not necessarily invalid. Although edges which were defined as robust can be interpreted with the highest degree of confidence, all regularised edges may still be interpreted with a high degree of confidence, as network models fitted with gLASSO regularisation have been shown under simulation to perform well in retrieving true networks (Epskamp et al., Reference Epskamp, Borsboom and Fried2018; Foygel & Drton, Reference Foygel and Drton2010; Van Borkulo et al., Reference Van Borkulo, Borsboom, Epskamp, Blanken, Boschloo, Schoevers and Waldorp2015). Further, the wide 95% CIs estimated around NOA edges do not affect interpretation of their validity. As edges have already been selected as non-zero by gLASSO, 95% CIs should be interpreted only as indicators of parameter strength estimate precision, and not significance tests. However, despite gLASSO generally performing well in retrieving true network structures, more recent work has suggested that estimating parameter stability and accuracy is an important safeguard against false-positive findings (Fried, Van Borkulo, & Epskamp, Reference Fried, Van Borkulo and Epskamp2020). This is particularly important for the present paper, as inferences are made based on the presence or absence of specific edges (rather than global network properties). When concerned with specific edges, false-positive edges lead directly to erroneous conclusions. To account for this, the extra step has been taken to define robust edges as those which were replicated in at least 70% of bootstraps using both the GGM and MGM estimation procedures. Thus, the full steps taken to ensure valid NOA results are: (a) regularised model selection; (b) two cross-checked estimation procedures, from which the higher specificity GGM models were presented; (c) bootstrapping all NOA models to estimate the accuracy and robustness of parameters, from which the most robust were identified.

All seven robust (P_n−_z > 0.70) NOA edges were positive. Of these, four childhood items belonged to the social-emotional community, two belonged to the worried-emotional community, and one belonged to the fearful-withdrawn community. When looking at the individual items, this trend is also borne out. The item solitary, tends to do things alone (AW10) formed a robust edge with the AD outcome in both male NOA models. Five other childhood items each formed one robust edge with later AD: afraid of being left alone (AW3), cries easily and often (AW5), often appears miserable (AW6), feelings easily hurt (AW9) and overly sensitive (AW11). All of these items except AW3 describe behaviours relating to social problems and sadness. A preponderance of items related to social problems and sadness is also observed when looking at all regularised NOA edges estimated as non-zero (also including those where P_{n −z} < 0.70 across bootstraps). Of the 16 positive NOA edges, 13 belonged to either the social-emotional or worried-emotional communities. The item solitary, tends to do things alone (AW10) formed an edge with later AD in three NOA models. The items cries easily and often (AW5), often appears miserable (AW6), often worried (AW7) and overly serious or sad (AW12) each formed an edge with later AD in two NOA models. The items afraid of new things or situations (AW1), afraid of being left alone (AW3), worries about illness or death (AW4), feelings easily hurt (AW9) and overly sensitive (AW11) each formed an edge with later AD in one NOA model. Items describing fearful behaviours (AW1–AW3) and authority figure-specific behaviours (AW13–AW15) did not consistently predict later AD by any measure. This applied across both the male and female subsamples and both the adolescent and adult AD outcomes. Either by considering all regularised NOA edges, or only those which were considered robust, items describing sad and unsocial behaviours formed edges with later AD consistently when compared to items describing situational fears and responses towards authority figures.

These findings build substantially on the work of another NOA investigating AD outcomes from childhood items. In their study of childhood emotional and behavioural symptoms as predictors of later AD in a female sample, Rouquette et al. (Reference Rouquette, Pingault, Fried, Orri, Falissard, Kossakowski and Borsboom2018) found that the item tends to play alone, solitary at age 10 was associated with AD at age 15 or 22 follow-up. The results from the present NOAs provide further evidence that female children described as solitary are at increased risk of later AD. Moreover, the present research extends this finding to male children. The finding of Rouquette et al. (Reference Rouquette, Pingault, Fried, Orri, Falissard, Kossakowski and Borsboom2018) that fear was associated with later AD in female children was not replicated with the items in the present study. An earlier longitudinal study by Roza et al. (Reference Roza, Hofstra, Van Der Ende and Verhulst2003) found that a social problems scale administered at age 14, including items such as gets teased a lot and not liked by other kids, significantly predicted later AD. The present finding that solitary behaviour in middle childhood predicts later AD in males and females is also consistent with the findings of Roza et al. (Reference Roza, Hofstra, Van Der Ende and Verhulst2003).

The NOA results also indicate that the risk incurred by childhood anxiety/withdrawal items may not be constant over time. In our male subsample, two edges were formed between fearful childhood items and adolescent AD. The item afraid of being left alone (AW3) formed a robust edge, while afraid of new things or situations (AW1) formed an edge that did not meet the criteria for robustness. However, no edges were retrieved between fearful childhood items and adult AD. This may suggest that some fearful childhood behaviours, such as a fear of being left alone, predict anxious continuity into adolescence, but the risk associated with these behaviours diminishes in adulthood. Indeed, fears of specific objects and situations, such as being left alone, are common features of anxious behaviour in childhood, and typically reduce after puberty (Beesdo-Baum & Knappe, Reference Beesdo-Baum and Knappe2012; Pine & Fox, Reference Pine and Fox2015). Conversely, NOA models suggest that social and emotional aspects of childhood anxiety/withdrawal may have more persistent continuity into adulthood. Following developmental theories of anxiety, social and emotional symptoms are a typical feature of anxiety in adolescence and adulthood; they are less typical of childhood anxiety, where specific and situational fears are theorised to arise from challenges associated with that developmental period (Weems, Reference Weems2008; Westenberg, Siebelink, & Treffers, Reference Westenberg, Siebelink and Treffers2001). Considering this, it may be that children in mid-childhood exhibiting more developmentally advanced (i.e. social and emotional) anxious behaviours carry more risk for anxious continuity compared to children exhibiting situation-based fears more typical of their developmental stage.

Limitations

There are some limitations to the present study. First, the overall replicability of network analyses has recently garnered substantial discussion (Borsboom et al., Reference Borsboom, Fried, Epskamp, Waldorp, van Borkulo, van der Maas and Cramer2017; Forbes, Wright, Markon, & Krueger, Reference Forbes, Wright, Markon and Krueger2017a, Reference Forbes, Wright, Markon and Krueger2017b; Jones, Williams, & McNally, Reference Jones, Williams and McNally2019). Several steps were taken to mitigate the potential for false-positive findings. In particular, a thorough analysis of parameter accuracy and robustness has shown that important NOA findings are not likely to have been affected by false-positive edges. However, the relatively wide 95% CIs around NOA edges indicate that strength estimates of these parameters are not precise. Second, the scale used in the present study was developed to measure a latent dimension of childhood anxiety/withdrawal. As it was not created to be modelled at the level of its components, it may be missing important variables within the true causal system of childhood anxiety/withdrawal (Jones, Heeren, & McNally, Reference Jones, Heeren and McNally2017). Third, the present study did not control for covariates due to statistical power constraints. Previous research with the CHDS dataset found that the association between the summed childhood anxiety/withdrawal scale and later AD was only slightly attenuated after controlling for psychosocial covariates such as childhood sexual and physical abuse, adverse life events, and parental history of anxiety and depression (Goodwin et al., Reference Goodwin, Fergusson and Horwood2004; Jakobsen et al., Reference Jakobsen, Horwood and Fergusson2012). Last, there were several limitations related to the study cohort and data collection procedures worth mentioning. There was a significant difference in overall childhood anxiety/withdrawal between participants who completed the first outcome assessment, and those who did not. This suggests that participants who dropped out of the study tended to have slightly higher baseline anxiety/withdrawal, possibly introducing a selection bias. It has also previously been found that trait variation accounts for approximately a quarter to half of observed variance in childhood scale scores in the CHDS cohort, with the rest being accounted for by method effects and error. This may partially explain the relative lack of difference observed in male and female childhood networks. It should also be considered that the first two outcome assessments used a different diagnostic criteria (DSM-III-R) than subsequent assessments (DSM-IV). This may have contributed to some differences between the adolescent and adult NOAs (e.g. the robust edge between AW3 and adolescent AD in males). Finally, this study is based on data from one population birth cohort over a particular period of time. The degree to which these networks may generalise to different places and times is unclear.