Psychosocial stress predicts future symptom severities in children and adolescents with Tourette syndrome and/or obsessive-compulsive disorder

Abstract

Background: The goals of this prospective longitudinal study were to monitor levels of psychosocial stress in children and adolescents with Tourette syndrome (TS) and/or obsessive-compulsive disorder (OCD) compared to healthy control subjects and to examine the relationship between measures of psychosocial stress and fluctuations in tic, obsessive-compulsive (OC), and depressive symptom severity.

Methods: Consecutive ratings of tic, OC and depressive symptom severity were obtained for 45 cases and 41 matched healthy control subjects over a two-year period. Measures of psychosocial stress included youth self-report, parental report, and clinician ratings of long-term contextual threat. Structural equation modeling for unbalanced repeated measures was used to assess the temporal sequence of psychosocial stress with the severity of tic, OC and depressive symptoms.

Results: Subjects with TS and OCD experienced significantly more psychosocial stress than did the controls. Estimates of psychosocial stress were predictive of future depressive symptoms. Current levels of psychosocial stress were also a significant predictor of future OC symptom severity, but not vice versa. Current OC symptom severity was a predictor of future depressive symptom severity, but not vice versa. Current levels of psychosocial stress and depression were independent predictors of future tic severity, even after controlling for the effect of advancing chronological age.

Conclusions: The impact of antecedent psychosocial adversity is greater on future depressive symptoms than for tic and/or OC symptoms. Worsening OC symptoms are also a predictor of future depressive symptoms. Advancing chronological age is robustly associated with reductions in tic severity.

Figure 1

Group-specific stress measures. Stress scores at each time point (Baseline = TB, visit 4, 8, 12, 16, 20, 24 months after baseline = T4, T8, T12, T16, T20, T24, respectively) over the two-year period were averaged separately across patients and controls. Stress scores are plotted for Perceived Stress Scale – Parent (PSS-P), Daily Life Stressors Scale Parent (DLSS), and Yale Children’s Global Stress Index (YCGSI). Stress levels for all the three stress ratings PSS-P, DLSS, and YCGSI over the two-year period are significantly higher among the patients with TS and/or OCD than those among the normal controls (Z = 6.97, p < .0001 for PSS-P; Z = 3.95, p < .0001 for DLSS; and Z = 2.84, p = .0045 for YCGSI)

Figure 2

Trajectories of YGTSS and CY-BOCS. Yale Global Tic Severity Scale (YGTSS) and Children’s Yale-Brown Obsessive Compulsive Scale (CY-BOCS) symptom severity scores are plotted among the patients over the two-year period (TB to T24)

Figure 3

Pathway analyses of the relationships between longitudinally collected measures of psychosocial stress and tic, obsessive-compulsive (OC) and depressive symptom severity. Squares depict measured variables and circles represent latent variables. The standardized coefficients represent the size of the effects and the p-values in parentheses represent the significance of these effects as a result of the Wald test. An effect is deemed to be statistically significant if the p-value for the Wald test for each of the γ’s,α’s and β’s is smaller than .05 (see text). The standardized coefficients are the proportion of 1.0 standard deviation (SD) of the predicted variable that can be explained by 1.0 SD change in the predicting variable. A solid line indicates a statistically significant positive relationship; a dashed line indicates a significant inverse relationship. The thickness of the lines reflects the relative significance of the interactions. An arrow indicates a predictive relationship, while a line without an arrow head indicates the relative contributions to a latent variable. (A) Tic symptoms. In this model, future tic improvement was associated with advancing chronological age. The standardized coefficient of .38 means that following an increase of 2.7 years of age (1 SD of all measures of age in the patient population), we observed a reduction of 38% of 1.0 SD of all the YGTSS scores (.38 × 9.0 = 3.4). In addition, increases in past depressive symptoms (Children’s Depression Rating Scale-Revised, CDRS-R_T−1) predict higher levels of current psychosocial stress (Stress Construct, SC), which in turn modestly, but significantly, predict increases in future tic severity (Yale Global Tic Severity Scale, YGTSS_T+1). Increases in current depressive symptoms (Children’s Depression Rating Scale-Revised, CDRS-R_T) are also modestly, and independently, predictive of increases in future tic symptom severity (YGTSS_T+1). Prior tic symptom severity (YGTSS_T−1) does not affect current depressive symptom ratings; and past YGTSS scores also do not significantly affect current stress levels (data not shown). The SC is a latent variable derived from the Yale Children’s Global Stress Index (YCGSI), the Perceived Stress Scale–Parent (PSS-P) and the Daily Life Stress Scale (DLSS). (B) Obsessive-compulsive (OC) symptoms. Higher levels of psychosocial stress in the past (SC_T−1), predict higher levels of current obsessive-compulsive symptom severity (Children’s Yale-Brown Obsessive Compulsive Scale [CY-BOCS_T]), which subsequently predicts future depressive symptom severity (CDRS-R_T+1). The standardized coefficient of .47 means that following an increase of 8.2 units on the CY-BOCS (1.0 SD of all measures of OC symptom severity in the patient population), we estimated an increase of 47% of 1.0 SD of all the CDRS-R scores (.47 × 8.7 = 4.1 units). (C) Depressive symptoms. The previous (time-lagged) depressive symptom severity (CDRS-R_T−1) strongly predicts current levels of psychosocial stress (SC), which subsequently predicts future levels of depressive symptoms (CDRS-R_T+1). The standardized coefficient of .73 means that following an increase of 3.3 units on the PSS-P (1.0 SD of all measures on the PSS–P in the patient population), we estimated an increase of 73% of 1.0 SD of all the CDRS-R scores (.73 × 8.7 = 6.4 units)