Tic disorders and obsessive compulsive disorder: where is the link? V. Roessner, A. Becker, T. Banaschewski, and A. Rothenberger Department of Child and Adolescent Psychiatry, University of Goottingen,€ Germany Summary. Over the last years evidence on the overlap between tic-disorders (TD) and obsessive compulsive behavior=disorder (OCB=OCD) has increased. The main focus of research have been the phenomenological and epidemiolog- ical similarities and differences in samples of different age, primary diagnosis (TD vs. OCD) including the co-occurrence of both. Unfortunately, only a minority of studies included all three groups (TD, TD þ OCD, OCD). Never- theless, new insight concerning possible subtypes for both TD and OCD has been gained. While some authors concentrated on OCD with=without tics we will summarize the field of TD and OCB=OCD from the viewpoint of tics, since OCB plays an important role in patients with TD. Thereby we will not only sharpen the clinicans’ awareness of known differences in phenomenology, epi- demiology, genetics and neurobiology, aimed to improve their diagnoses and treatment but also highlight the gaps of knowledge and discuss possibilities for further research in this field. Introduction Since the 1980ies the clear distinction between tic-related and non-tic-related obsessive compulsive disorders (OCD) has received support from phenome- nologic, family-genetic, psychopharmacologic, and neuroendocrine studies (Hanna et al., 1991; Leckman et al., 1994a; McDougle et al., 1994; Pauls et al., 1995). Within the last years only four reviews have been published in journals on this issue. In 2001 Miguel et al. (2001) focused on OCD and its relationship to tics by presenting the findings of studies investigating phenomenological simi- larities, the patients subjective experiences associated with obsessive compul- sive behavior (OCB) and the possible overlap of OCD þ TD with early onset OCD and Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus (PANDAS). Swerdlow (2001) chose a more balanced view con- cerning the weighting between tics and OCB. Two years later Miguel et al. (2003) summarized treatment strategies in OCD and their modifications when tics coexist. In the same year Banaschewski et al. (2003a) reviewed the basis of 70 V. Roessner et al. knowledge concerning compulsive phenomena in children with TD and atten- tion deficit-hyperactive disorder (ADHD). Since then some progress has been made. Based on the proposed tic-related subtype of OCD not only studies on phenomenological or epidemiological questions, but also more specific studies in genetics (Castillo et al., 2004; Hemmings et al., 2003; Urraca et al., 2004), psychopharmacology (Geller et al., 2003), behavioral therapy (Himle et al., 2003) and immunology (Hoekstra et al., 2004b; Murphy et al., 2004) have been done. Another way to approach the overlap between TD and OCD is subtyping both disorders (Calamari et al., 2004; Leckman, 2003). The development of such categories has made great progress and they have been used in non-phenomenological studies already, showing promising results, e.g. (Zhang et al., 2002). Therefore an actual overview seems to be helpful in order to update the work of Miguel et al. (2001). While these authors started from OCB=OCD looking towards TD, our perspective will be the other way around, i.e. from TD towards OCB=OCD, which is a more common problem in childpsychiatric practice. Phenomenology The co-occurrence of tics and OCB is known in medicine since more than hundred years (Gilles de la Tourette, 1885). Over the times many different attempts to clarify the psychopathologic similarities and differences between tics and OCB have been undertaken (see Table 1). We will describe the state of the art concerning phenomenological aspects between the ‘two poles of a spectrum’ ranging from TD to OCD (Moll and Rothenberger, 1999) and take Table 1. Clinical differences and similarities of tics (TIC) and obsessive- compulsive behavior (OCB) TIC OCB Differences Sudden, short (jerking=twitching) ritualistic Fragmented movement goal directed behavior Premonitory urges (sensorimotor) thoughts=images (cognitive- emotinal dissonance) Not anxiety-related mostly anxiety-related Ego-syntonic ego-dystonic Involuntary (clustering sequence) Voluntary (cycling) Onset with elementary school (one peak) onset after elementary school (two peaks) Waxing and waning (from seconds little change over time to month) Also during sleep never during sleep Similarities Concentration decreases concentration decreases Expressed emotions increases expressed emotions increases Suppressible (shortterm) suppressible (longterm) Tic disorders and obsessive compulsive disorder 71 a special look on sensory phenomena, supressibility, impulsivity and self injurious behavior. This might help clinicans to improve their diagnoses and treatment of patients of the comorbid group. Tics are defined as sudden, involuntary, brief, rapid and non-rhythmic motor movements or vocal productions in the presence of unimpaired motor skills (Leckman, 2003). They cause purposeless and stereotyped motor actions (motor tics) or sounds (vocal tics) that are not suited to the circumstances, but can be sometimes confused with goal directed behavior (Leckman et al., 2001). Tics can be classified by their appearance, frequency, intensity and com- plexity (Leckman, 2003). Each of these factors has been included in clinical rating scales that have proven to be useful in monitoring tic severity (Goetz and Kompoliti, 2001; Leckman et al., 1989; Walkup et al., 1992). One common feature for the classification of tics is the subdivision into motor vs. vocal tics (Leckman et al., 1989). Another dichotomous subdivision is based on the ‘complexity’ of tics: simple vs. complex tics. The first group involves only isolated muscles or sounds. The predominance of single patterns of simple tics varies between the studies and countries, but craniofacial tics are almost always much more common than truncal-axial tics (Chee and Sachdev, 1994). Anatomically, there is a rostro-caudal increase in age of onset of simple motor tics. The existence of similar changes of a special feature of OCB has not been investigated so far. Tics can fluctuate from one part of the body to another. Interestingly it is sometimes reported by TS patients that there is a suggestibility of tics, i.e. old tics may transiently reappear (Robertson et al., 1999). Both could be observed in a similar way in OCB. Since almost any voluntary movement or sound can emerge as a motor or vocal tic (Leckman et al., 1998a), this can lead to problems in differentiating between tics and OCB, particularly if complex motor tics exist (Evidente, 2000; Moll and Rothenberger, 1999; O’Connor, 2001). Because all types of TD are more common in families with any TD, several studies have suggested that the various TD diagnoses exist along a single con- tinuum defined by type and duration of the tics (Singer and Walkup, 1991) and that there is a genetic component in TD. The most commonly used diagnostic scheme, as outlined in the DSM-IV (American Psychiatric Association, 1994), divides TD into three main tic categories: transient TD (TTD), chronic motor or chronic vocal TD (CMTD or CVTD), and Tourette’s disorder=syndrome (TS). The most salient features of TTD are the fact that individuals can have both multiple motor and vocal tics and that the total duration of tic symptoms is no longer than 1 year. CMTD or CVTD are defined by the presence of either motor or vocal tics lasting more than 1 year. TS criteria require that both multiple motor and one or more vocal tics have been present during the illness, although not necessarily simultaneously. A course of more than 1 year without a tic-free period of more than 3 consecutive months has also to be present. The latest model of possible subtyping of TD has been developed by Alsobrook and Pauls (2002). They have recently used an agglomerative 72 V. Roessner et al. hierarchical cluster and factor analysis to identify TS symptom dimensions for the future use in studies in the field of TD. Four symptom dimensions were identified, including: (1) aggressive phenomena (e.g., kicking, temper fits, argu- mentativeness), (2) purely motor and vocal tic symptoms, (3) compulsive phe- nomena (e.g., touching of others or objects, repetitive speech, throat clearing), and (4) tapping and absence of grunting. The same approach to identify reliable and valid subtypes has been con- ducted in OCD, but the data are more widespread. In the different models nearly all based on Y-BOCS (for an overview see Table 1 in Calamari et al. (2004)) the number of subgroups ranges between 3 to 5 and in recent work greater support was found for a seven subgroup taxonomy. In all models three dimensions have been found: Contamination=Washing, Harming=Checking and Symmetry=Ordering. But in both single disorders (TD or OCD) and especially in the comorbid group (TS þ OCD) additional work remains to be done to test the suitability of these models of subtyping. Furthermore, it has to be clarified to which extent the dimension ‘compulsive phenomena’ of the model of Alsobrook and Pauls (2002) overlaps with the subtype ‘tic-related OCD’. Nevertheless, the potential for this effort remains high to elucidate etiolog- ical processes and improve treatment and research outcome (Calamari et al., 2004; Leckman, 2003). Sensory phenomena A sensory component preceding a motor tic has been described in numerous case reports and series (Bliss, 1980; Bullen and Hemsley, 1983; Cohen and Leckman, 1992; Kurlan et al., 1989; Lang, 1991; Leckman et al., 1994b; Miguel et al., 2000). In larger samples of patients with TD the frequency of various sensory phenomena ranges between 37% (Banaschewski et al., 2003b) to over 90% (Leckman et al., 1993). An increase during child development (not dependent on duration of TD) has been shown (Banaschewski et al., 2003b). These premonitory sensations have been named as ‘sensory tics’, ‘internal tics’, ‘an urge’, an ‘impulse’, an ‘itch’, a ‘pressure’, and the ‘just right’ phenomenon (Cohen and Leckman, 1992; Kurlan et al., 1989; Leckman et al., 1993, 1994b).