بررسی تاثیر حواس پرتی بر جلوگیری از تیک در کودکان و نوجوانان مبتلا به سندرم تورت

Abstract Tourette syndrome (TS) is characterized by motor and/or vocal tics. Tics are thought to be temporarily suppressible, and it is believed that suppression requires significant attentional resources. The aim of the current study was to examine the impact of an attention-demanding distraction task on tic suppression. A secondary aim was to examine whether performance on that task decreased during concomitant periods of suppression. Nine children with TS, ages 9–15, participated in the study. An alternating treatment design was used to compare three conditions, free-to-tic baseline (BL), reinforced tic suppression (SUP) and reinforced tic suppression plus a distraction task (SUP + DIS). Tic frequencies were significantly higher during BL conditions than both SUP and SUP + DIS conditions, and tic frequencies during SUP and SUP + DIS did not differ. Accuracy on the distraction task decreased during SUP + DIS as compared to BL. Results suggest that contextual distractions may not negatively impact tic frequencies. In addition, accuracy on an attention-demanding task may be impacted if a child is simultaneously suppressing.

Introduction Tourette syndrome (TS) is a childhood onset neuropsychiatric disorder characterized by recurrent, sudden, stereotyped motor movements and vocalizations called motor and vocal “tics,” respectively (American Psychiatric Association [APA], 2000). Tic disorders are estimated to occur in 0.04–3.0% of the population (Hornsey et al., 2001 and Mason et al., 1998) and are more common in males than females. Over 50% of those with TS have a co-occurring psychiatric condition, the most common being attention-deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD; Freeman et al., 2000). Although tics are involuntary, research has supported the notion that they can be temporarily suppressed to varying degrees (Jankovic & Fahn, 1986). Unfortunately, little is known about the development of tic suppression abilities or the mechanisms responsible for suppression. Research in this area has suggested that contextual factors and attentional processes may play key roles in tic suppression (Conelea and Woods, in press, Himle and Woods, 2005 and Peterson et al., 1998). Numerous studies using survey or otherwise uncontrolled research designs have suggested that tic expression can vary depending on one's context or emotional state (e.g., Bornstein, Stefl, & Hammond, 1990; Eapen, Fox-Hiley, Banerjee, & Robetrson, 2004; O'Connor et al., 2003 and Silva et al., 1995). To better understand how such factors impact tic expression, researchers have begun to examine tic suppression in studies using controlled experimental designs. Meidinger et al. (2005) examined the impact of instructing children and adults with TS (N = 7) to suppress their tics. Using a withdrawal design, two conditions were compared: (1) a non-suppression baseline and (2) a condition in which the subject was told to suppress his/her tics. Significant reductions in tic frequencies were observed in almost one half of all suppression conditions, indicating that tics are somewhat suppressible in the presence of a verbal instruction to do so, at least for temporary amounts of time. Woods and Himle (2004) suggested that natural suppression rarely involves reacting to simple instructions to suppress. Rather, they noted that children may encounter reinforcing consequences for successfully suppressing tics. For example, suppression may result in avoidance of teasing or increased ability to engage in activities that might be disrupted by tics, such as playing sports or talking with others. To determine if reinforcement for suppression could impact tic occurrence, Woods and Himle used a withdrawal design in which three 5-min conditions were administered repeatedly: (1) baseline, (2) verbal instructions to suppress, and (3) contingent reinforcement for suppression, in which tokens (exchangeable for a prize) were delivered for every 10-s tic-free period. Averaged across the four participants, the verbal instructions condition produced a 10.3% reduction in tic rates from baseline levels, whereas the reinforcement condition produced a 76.3% reduction. These results suggested that tic suppressability may be enhanced by operant contingencies. Other studies have used the Woods and Himle (2004) preparation to further examine the relationship between contextual factors and tic suppression (Himle and Woods, 2005 and Himle et al., 2008; Himle et al., 2007 and Woods et al., 2008). These studies have shown that tic suppression (a) does not necessarily produce a rebound in tic frequency (Himle & Woods; Woods et al.), (b) is capable of being maintained for up to 40 min (Woods et al.), (c) requires the contingent delivery of a reinforcer to produce maximum suppression (Himle et al., 2007), and (d) is functionally related to urges to tic (Himle et al., 2008). Combined, these studies have examined a number of factors that could give rise to tic suppression. However, contextual factors may also disrupt successful suppression. Identification of such factors may help to answer the question of how tic suppression is accomplished. In addition, it may help to inform behavioral interventions designed to enhance tic suppression ability (e.g., Azrin and Nunn, 1973 and Deckersbach et al., 2006). Many factors may be related to one's ability to suppress tics, but research to date has suggested that attentional processes may be particularly important. Himle and Woods (2005) found a significant negative correlation between the Attention Problems subscale of the CBCL and tic suppressability (r(7) = −.89, p < .01), suggesting that poorer suppressability is related to increasing attention problems. Likewise, Woods et al. (2008) found a significant correlation between the ability to suppress and omission errors on a continuous performance task (r(11) = −0.63, p < 0.05), leading the authors to conclude that poor task orientation was related to poor tic suppression ability. Brain imaging research also supports the notion that tic suppression involves attentional processes. Using fMRI, Peterson et al. (1998) observed significant changes in cortical regions thought to subserve attention-demanding tasks during periods of voluntary suppression. The authors concluded that tic suppression is an attention-demanding task that involves a constant monitoring of somatosensory information. Finally, it has been suggested that performance deficits on attention-demanding tasks may occur when attentional efforts are directed to tic suppression ( Shimberg, 1995). Although attentional processes have been implicated in tic suppression, the relationship has not been experimentally tested at the behavioral level. In the current study, we sought to explore the link between attentional processes and tic suppression by examining tic suppression in the presence and absence of a competing attention-demanding task. We proposed two hypotheses based upon research suggesting that tic suppression is an attention-demanding task. First, we hypothesized that tic frequencies would be higher during periods of suppression plus distraction as compared to periods of suppression alone. Second, we hypothesized that children would demonstrate decreased accuracy on an attention-demanding task during periods in which suppression was coupled with distraction as compared to performance on the task before and after the experimental portion of the study.

Results Analytic plan Although the study was designed as a single-subject experimental design, our use of an alternating treatment approach allows us to summarize the results using inferential group statistics. After the summary of these analyses, we discuss the individual data patterns. Suppression findings Mean tic frequency scores for each condition were calculated by summing the mean scores for each child in each of the three conditions (BL, SUP, SUP + DIS). A one-way repeated measures analysis of variance was significant, F(1, 2) = 7.4, p = .005, d = 1.34. Subsequent analyses indicated that tic frequencies were significantly higher during the BL conditions (M = 46.6, SD = 42.8) than the SUP (M = 5.5, SD = 6.1, p = .02, d = 1.34) and the SUP + DIS conditions (M = 7.1, SD = 5.7, p = .03, d = 1.29). Tic frequencies during SUP and SUP + DIS did not significantly differ (p = .51, d = −.27). CPT accuracy findings CPT data were examined to determine if CPT performance during the SUP + DIS conditions differed from performance before and after the experimental procedure was conducted. First, baseline (pre- and post-experimental) CPT administrations were compared using a paired samples t-test to ensure that they did not differ. Hits on the pre (M = 40.2, SD = 2.5) and post (M = 40.8, SD = 1.3) CPT administrations did not differ (t = −.5, p = .6), nor did errors of commission (pre: M = .6, SD = .4; post: M = 0, SD = 0; t = 1.5, p = .2). Therefore, we combined these scores to create one baseline mean of hits and one baseline mean of commission error scores. These means were compared to mean scores obtained during the SUP + DIS conditions using paired samples t-tests. Hits significantly differed between pre/post (M = 39.6, SD = 2.7) and SUP + DIS (M = 35.9, SD = 6.2) administrations (t = 2.5, p = .04, d = .77). Commission errors did not differ between pre/post (M = .5, SD = .7) and SUP + DIS (M = .8, SD = .9) administrations (t = −.8, p = .42, d = −.37). Individual CPT data are presented in Table 2. Table 2. Hits and commission errors (Com.) on the auditory CPT for each participant Participant Pre SUP + DIS 1 SUP + DIS 2 SUP + DIS 3 Post Hits Com. Hits Com. Hits Com. Hits Com. Hits Com. 1 42 2 38 2 36 0 40 1 n/a n/a 2 42 0 39 0 37 0 42 0 42 0 3 42 0 36 0 29 0 31 0 41 0 4 37 1 40 0 41 0 37 1 40 0 5 40 0 40 0 37 1 29 5 n/a n/a 6 38 2 38 1 42 0 42 1 42 0 7 n/a n/a 35 0 33 1 37 0 39 0 8 42 0 42 0 42 0 40 0 39 0 9 33 1 24 1 20 3 n/a n/a n/a n/a Table options Single-subject analyses We examined the data at the individual level by plotting tic frequency data and analyzing them for changes in magnitude using both visual inspection procedures and randomization tests (Levin, Marascuilo, & Hubert, 1978) with accompanying effect size estimates (Olive & Smith, 2005). Individual tic frequency data are presented in Fig. 1, and individual statistical data are presented in Table 3. Tic frequencies during baseline (BL), suppression (SUP), and suppression plus ... Fig. 1. Tic frequencies during baseline (BL), suppression (SUP), and suppression plus distraction (SUP + DIS) conditions for each participant. Figure options Table 3. Tic frequency means, standard deviations, mean differences and non-regression effect sizes for each participant Participant BL SUP SUP + DIS BL vs. SUP BL vs. SUP + DIS DRO vs. SUP + DIS M SD M SD M SD MBL − MSUP d MBL − MDIS d MSUP − MDIS d 1 45.0 10.4 12.0 16.5 16.0 5.3 33.0* 3.1 29.0* 2.8 4.0 −0.2 2 73.7 14.3 1.7 0.6 12.0 19.9 72.0* 5.0 61.7* 4.3 10.3 −18.1 3 25.7 14.6 3.3 1.2 8.3 10.4 22.3* 1.5 17.3 1.2 5.0 −4.4 4 16.7 10.5 1.0 0 3.3 3.1 15.7* 1.5 13.3* 1.3 2.3 −2.3 5 63.3 68.5 17.0 19.9 2.7 2.1 46.3 0.7 60.7* 0.9 14.3 0.7 6 145.0 36.2 0 0 0.3 0.6 145.0* 4.0 144.7* 4.0 −0.3 0 7 17.3 3.5 5.0 5 9.7 12.7 12.3* 3.5 7.7 2.2 4.7 −0.9 8 15.0 11.1 0 0 0 0 15.0* 1.3 15.0* 1.3 0 0 9 18.5 9.2 10.0 1.4 11.5 3.5 8.5* 0.9 7.0 0.8 1.5 −1.1 *Mean difference is significant at p = .05. Table options Five children (participants 1, 2, 4, 6, and 8) demonstrated a similar data pattern. There were no BL data points that overlapped with SUP or SUP + DIS data points, while in all cases the SUP and SUP + DIS data points did overlap. This pattern suggests a clear difference in tic frequencies between BL and both suppression conditions. Individual statistical data (see Table 3) indicated that the mean difference between tic frequencies during BL and SUP was significantly different for eight children (participants 1–4 and 6–9), and the mean difference between BL and SUP + DIS was significantly different for six children (participants 1,2, 4–6, 8). These findings suggest that tic suppression reliably occurred in both suppression conditions for the majority of participants (1, 2, 4, 6, 8). Only a few children deviated from this pattern (3, 5, 7, 9) and it is worth noting that if the first BL condition for participants 3 and 5 were removed (as they failed the manipulation check for these conditions), their response pattern would have been similar to participants 1, 2, 4, 6, and 8. Only tic frequency data from participants 7 and 9 showed patterns that were inconsistent with the remaining participants. Both participants 7 and 9 demonstrated successful suppression in the SUP condition, but not when distraction was added. Although reasons for this are unclear, it is interesting to note that both children had co-occurring OCD and disruptive behavior disorder (e.g., conduct disorder or ADHD) diagnoses.