Analyzing the underlying symptom-dimensions of Gilles de la Tourette Syndrome.
Jong, D.T.H.A. de
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Aim: Gilles de la Tourette syndrome (GTS) is a complex and heterogeneous disorder which might best be viewed as part of a spectrum of tics and comorbidities. There has been little research on GTS and its co-morbid disorders on a symptom dimension level. Our hypothesis is that our model of symptom dimensions across tic symptoms and symptoms of OCD and ADHD will provide a good fit, will better represent the heterogeneity of the disorder and comorbid symptoms between disorders will partly correlate. Method: Our total study sample included 225 patients and 371 family members, summing up to a total of 596 participants. Using Mplus 5.21, a Confirmatory Factor Analysis (CFA) was conducted on a total of 10 symptom dimensions, covering GTS and comorbid OCD and ADHD. Results: Our symptom dimension model fit the data best (Δχ2 >0.948, p <0.001) and presented the lowest AIC (ΔAIC = -224). The OC dimensions Taboo (0.773) and Rituals (0.657) correlate highest with the tic symptom dimensions (p = < 0.05). Of the GTS dimensions the body tics dimension correlates lowest with OC symptom dimensions (0.731, p < 0.05). Surprisingly, the ADHD dimensions showed no correlations with the other symptom dimensions. Conclusion: In line with previous research (Mathews et al. 2009, Cath et al. 2004) our data suggest that overall 10 symptom dimension model (Katerberg, 2010; de Haan, 2010; (American Psychiatric Association [DSM-IV-TR], 2000) is superior to the 1 factor model. The OC symptom dimension Taboo showed the highest correlation with GTS. The symptom dimension body tics showed the lowest correlation with OCD. Our ﬁndings complement earlier ﬁndings that the symptom dimensions of GTS and comorbid OCD can best be viewed as belonging to a spectrum of disorders, probably with shared underlying etiology. In contrast with the literature, ADHD seems to be independent from tic and OCD symptom dimensions. We do not have an adequate explanation for this finding.