Tourette syndrome (TS) is a neurobehavioral disorder characterized by multiple motor and one or more phonic tics. Comorbid disorders such as attention-deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD) are common.1,2 TS is associated with poor Quality of Life (QoL),3–6 including difficulties with social interaction.7–10 The study of QoL in TS can support the development of effective interventions and understanding the role of comorbid conditions may aid treatment prioritization.
Comorbid OCD and ADHD have an important influence on QoL in TS4,11 and the severity of these conditions can be more strongly related to QoL than tic severity.12 Various studies6,13–16 have shown that many of the psychosocial and behavioral difficulties experienced by children with TS are linked to comorbid OCD and/or ADHD. For example, Pringsheim et al.17 reported that the QoL scores of patients with TS and ADHD, or ADHD and OCD were lower in almost all psychosocial domains, whereas, for the “pure” TS (no comorbidities) subgroup, only the Family Activities domain was significantly affected.
First, we aimed to investigate the hypothesis that QoL differed in patients with “pure” TS, as compared with those with TS and either comorbid OCD or ADHD, or both comorbidities. Secondly, we aimed to explore whether symptoms relating to either OCD or ADHD may differently affect QoL domains. QoL was assessed with the multidimensional Youth Quality of Life Instrument–Research Version (YQL–RV).18,19 This instrument allowed investigation of whether OCD or ADHD exerted varying influences on perceived QoL in general and domains of QoL related to the self, relationships, and environment. This measure therefore allowed us to consider domains of QoL shown to be particularly important in TS, including social relationships.4 Clinical scales were included to assess variables that could differ between comorbidity groups, including tic severity, anxiety, depression, and behavioral problems, in addition to symptoms of OCD and symptoms of ADHD. Such clinical factors may interact to influence perceived QoL in TS.4,5,11,20–22
A group of 50 young people with TS according to DSM-IV-TR criteria participated. Age ranged from 11 to 17 years. The diagnosis of comorbid OCD and ADHD was established by the treating clinician in accordance with current DSM criteria. Eleven had pure TS (10 boys; mean age: 13.73; SD: 2.41); 13 had TS+OCD (11 boys; mean age: 13.77; SD: 2.62); 15 had TS+ADHD (14 boys; mean age: 12.40; SD: 1.84); and 11 had TS+OCD and ADHD (9 boys; mean age: 13.36; SD: 2.42). Thirty patients were taking medication: pure TS: 2 pimozide (1+fluoxetine), 1 aripiprazole; TS+OCD: 4 risperidone (1+fluoxetine), 2 pimozide (1+fluoxetine), 2 aripiprazole (1+fluoxetine), 1 sulpiride; TS+ADHD: 4 pimozide (1+clonidine), 3 aripiprazole, 1 risperidone; TS+OCD+ADHD: 7 pimozide (5+fluoxetine), 1 aripiprazole, 1 risperidone, 1 sulpiride.
The study received ethics approval. Patients were recruited consecutively from a pediatric outpatient clinic at the University of Catania, Italy, after giving informed consent. The QoL measure Youth Quality of Life Instrument–Research Version (YQOL–R)18,19 was completed, along with six clinical scales: the Yale Global Tic Severity Scale (YGTSS),23 the Multidimensional Anxiety Scale for Children (MASC),24 the Child Depression Inventory (CDI),25 the Child Behavior Checklist (CBCL),26 the Yale-Brown Obsessive Compulsive Scale (Y-BOCS)27 and the Conner’s ADHD/DSM-IV Scale (CADS).28
The 41 “perceptual items” contained in the YQOL-R generate scores for four domains. The Self domain (14 items) provides a perspective on the adolescent’s sense of the person who they are (e.g., “I feel good about myself.”). The Relationships domain (14 items) assesses family and peer relationships (e.g., “I am happy with the friends I have.”). The Environment domain includes 10 items, including “I feel my life is full of interesting things to do.”), and the General domain contains three broader items (e.g., “I enjoy life.”). Total scores are generated by summing the scores across the four domains.
The YGTSS is a reliable, clinician-rated scale, in which tic severity is assessed on the basis of number, frequency, intensity, complexity, and interference.
The MASC is a validated scale that assesses anxiety disorders in children and adolescents. It contains three subscales (physical, harm, and social), which are combined to generate a total score.
The CDI is a self-rated instrument that allows the diagnosis of major depressive or dysthymic disorder in children and adolescents age 7–17.
The CBCL is a validated, parent-rated scale assessing the frequency and intensity of behavioral and emotional difficulties shown by a child over the preceding 6 months. It contains 8 syndrome scales (withdrawn, somatic complaints, anxious/depressed, social problems, thought problems, attention problems, delinquent behavior, and aggressive behavior) and 2 composite scales (externalizing and internalizing problems).
The Y-BOCS is a reliable, clinician-rated instrument used to assess the severity of obsessive-compulsive symptoms in children. Obsessions and compulsions are recorded, based on observation and child and parent report, and their severity is rated in terms of number, frequency, intensity, resistance, and interference.
The CADS is a validated, self- and proxy-rated (parent, teacher) scale used with 12–18-year-olds. It is used to diagnose ADHD and can allow discrimination between subtypes (e.g., predominantly inattentive/hyperactive-impulsive).
We compared QoL in pure TS to each of the comorbidity groups in turn (TS+OCD; TS+ADHD; TS+OCD+ADHD) using ANCOVA, with QoL score (Total, then Domain scores) as the dependent variable, Group as fixed factor, and Age, YGTSS score, MASC score, CDI score, and CBCL score as covariates to be controlled for; we also investigated how the severity of OCD symptoms and ADHD symptoms was related to QoL scores across different domains.
Symptom scores for OCD and ADHD significantly differed across the comorbidity groups when age and scores on other clinical measures (MASC, CDI, CBCL, CADS/YBOCS) were included as covariates. Y-BOCS scores were significantly lower in pure TS than in both TS+OCD (F[7,1]=3.467; p=0.021) and TS+OCD+ADHD (F[7,1]=3.093; p=0.038). CADS scores were significantly lower in pure TS than both TS+ADHD (F[7,1]=3.902; p=0.011) and TS+OCD+ADHD (F[7,1]=11.301; p<0.001).
One significant difference was found for total QoL when relevant covariates were controlled for. The pure TS group exhibited significantly higher QoL total scores (Table 1) than the TS+OCD+ADHD group (F[5,1]=3.658; p=0.023). The other significant difference was for the QoL Relationships domain score. The pure TS group scored significantly higher than the TS+OCD+ADHD group (F[5,1]=2.932; p=0.046). No other significant differences were found.
The influences of OCD and ADHD symptom severity were then examined across the whole sample, to see whether these factors affected QoL domain scores differently. This allowed us to investigate the impact of OCD and ADHD symptoms regardless of diagnostic category and across a range of symptom severities. Y-BOCS scores were the following: significantly negatively related to QoL scores for the Relationships (Pr = –0.444; p=0.001), Self (Pr = –0.297; p=0.038), General (Pr = –0.404; p=0.004), and Environment domains (Pr = –0.296; p=0.039), in addition to QoL Total score (Pr = –0.426; p=0.002). CADS scores were only significantly related to QoL scores for the Self (Pr = –0.327; p=0.023), and Relationship domains (Pr = –0.323; p=0.025), in addition to QoL Total score (Pr = –0.359; p=0.012).
We have shown that when potentially confounding factors are controlled for, QoL in patients with TS is adversely affected by the presence of both OCD and ADHD. However, the presence of just one of these comorbid conditions may not lower QoL scores significantly. When separate domains of QoL were considered, relationships domain scores were significantly lower in TS+OCD+ADHD than in pure TS. The relationships domain contained items linked to feelings about interactions with and understanding from family and friends (e.g., “getting along with parents,” “satisfied with social life”). This finding supports previous research suggesting that the nature and quality of social relationships deserves attention in TS,12 although this area appears most vulnerable in complex cases, where symptoms linked to both OCD and ADHD are present.
Although other studies have shown that ADHD may be detrimental,13–16 our findings suggest that symptoms of comorbid OCD could have a more widespread negative impact on QoL. Severity of OCD symptoms was negatively related to poorer QoL within the Self, Relationships, Environment, and General domains, whereas ADHD symptoms appeared to have a more selective negative impact on the Self and Relationships domains. The Environment domain contains items linked to interaction between individuals and their surroundings, in terms of feeling safe and enjoying their environment (e.g., “l like trying new things;” “I look forward to the future.”). Although further research is needed, we tentatively suggest that the difference for the Environment domain could reflect an association between OCD symptoms and being less trusting of one’s surroundings, unlike ADHD symptoms, which may be linked to a drive to seek reward from the environment. However, it is also possible that characteristics of these comorbid conditions could directly influence individuals’ self-report of perceived QoL.29 Young people with ADHD may give a less-considered report because of attention difficulties, whereas patients with OCD may be more critical because of perfectionism. Whatever the case, such effects may not explain more specific differences in reported QoL across different domains. Future research should look at the impact exerted on QoL by different subtypes of comorbid ADHD.
One advantage of the present study was that we collected information about QoL directly from individuals with TS, because self-reported QoL of young patients with TS may differ from proxy report.9 However, there were a number of limitations, including small sample size, lack of a measure of functional impairment, likely overlaps between QoL items and clinical scale items (e.g., for depression) and the possibility that factors unrelated to clinical symptoms (e.g., living conditions, socioeconomic status) or medications could have affected scores on the QoL measure and clinical scales and contributed to differences between patient subgroups. Furthermore, it is likely that young people with TS face unique challenges and impacts on their QoL that may only be partly addressed by the QoL measure employed.
The findings from this study suggest that, as compared with pure TS, perceived QoL may only be significantly worse when comorbid OCD and ADHD are both present. Furthermore, the symptoms of these two conditions are likely to have different relationships with various factors affecting QoL. Here, we highlight the importance of considering the impact of complex symptomatology in TS when evaluating the efficacy of treatment through perceived QoL.
The authors are grateful to Tourettes Action-UK and USA-TSA for their continuing support.