Objective Tourette syndrome (TS) is a neuropsychiatric condition characterised by multiple motor and vocal tics, as well as a spectrum of behavioural problems. Previous research found that 76% of patients with TS experience depressive symptoms, with 13% fulfilling diagnostic criteria for depression. We set out to assess the severity of affective symptoms in patients with TS, in comparison to patients with primary affective disorders (recurrent major depressive disorder, rMDD; bipolar affective disorder types I/II, BPD-I/II), and healthy controls.
Method Both patients with affective disorders and controls completed the Beck Depression Inventory (BDI)-IA, whilst patients with TS completed the BDI-II. Total BDI-II scores were transformed using an equipercentile equating method for converting raw total BDI-II to BDI-IA scores. Data from 14/21 items had corresponding anchor points between the two versions and were therefore suitable for analysis.
Results This cross-sectional study included N=3,066 participants: TS (N=65), rMDD (N=696), BPD-I (N=1515), BPD-II (N=497), and controls (N=293). Depressive symptoms did not show any association with ethnicity or age. Patients with TS scored significantly higher than healthy controls (P=<.001) for all relevant items. When comparing depression ratings between patients with TS and patients with primary affective disorders, total BDI scores in TS were not significantly different from BPD-I or BPD-II, but significantly lower than rMDD (P=.030). Specifically, patients with rMDD scored higher on the self-criticalness, libido, suicidality and anergia items (P=.003 - >< .001). The TS group also showed statistically significant differences in BDI scores across gender, with female patients reporting higher scores (P=.013), particularly in the guilt, suicidality, crying, irritability and libido items (P=.047 - .002). >
Conclusion Depression appears to be a prominent feature in TS and seems to have a different phenotype to that in rMDD. Female patients with TS present a particularly high risk to develop severe depressive symptoms. This has relevant clinical implications in terms of screening, management and prognosis of this patient population.