1. Motor Processing and Brain Activity are Related to Cognitive-Behavioral Improvement in Chronic Tic and Habit Disorders
Irina Branet1,2 Caroline Hosatte-Ducassy1,4 Kieron P. O’Connor1,2,3 Marc E. Lavoie1,2.
1Centre de recherche Fernand-Seguin, Hôpital Louis-H. Lafontaine, Montreal, Quebec, Canada;
2Departement de psychiatrie, Universite de Montreal, Montreal, Quebec, Canada;
3Departement de psychologie, Universite du Quebec en Outaouais, Gatineau, Quebec, Canada;
4Collège Jean-de-Brébeuf, Montréal, Québec, Canada
Motor oddball task
Introduction
Gilles de la Tourette syndrome (TS) is a neuropsychiatric disorder with multiple motor and phonic tics, affected by a dysfunction of the basal-ganglia and frontal cortex: two regions related to motor functions.
Habit disorders (HD) patients present frequent, repetitive and disturbing behaviors such as nail biting or hair pulling. It is a common comorbidity among patients suffering from TS and/or obsessive-compulsive disorder (OCD).
Cognitive-behavioral therapy (CBT) can successfully improve symptoms in TS and HD adult patients; our CBT program specifically targets motor execution and inhibition in these behaviors.
Clinical improvement following CBT was reported to modify EEG asymmetry in post-traumatic stress disorders (Rabe et al., 2008). However, psychophysiological effects of CBT are still poorly understood in patients affected by tic disorders.
Goals
Compare the event-related brain potentials (ERP) in participants with TS and HD symptoms to controls.
Investigate the effects of a successful 16-week CBT on the P300 component during a motor and non-motor oddball task. Participants
Data acquisition
EEG signals were acquired through a digital amplifier (Sensorium Inc.) recorded from 58 tin electrodes, continuously sampled at 500 Hz (high-low pass: 0.01 and 30 Hz)
Analyses
Repeated-measures ANOVAs was applied to the P300 mean amplitude and latency (from 300 to 550 ms). The between-groups factor was ‘Group’ (TS, HD and controls), while the within-group factors were ‘hemisphere’ (left, right), ‘region’ (frontal, frontocentral, central, parietal) ‘condition’ (rare, frequent) and ‘time of assessment’ (Pre and post)
Oddball Tasks
The tasks consisted of two identical presentations of a visual oddball with frequent (80%) and rare (20%) visual stimuli (asterisk or circle). For the first (non-motor) task, the subject had to count the rare stimuli and report this to the experimenter. For the motor task, subjects had to respond with a left or right button press for rare and frequent stimuli respectively.
Fig. 1 Tourette group
Fig Habit disorders group
Frontal Parietal Frontal Parietal
1a b a b
P300
Fig. 3a
Motor oddball effect
(Pre-CBT)
Fig. 3b
Fig. 3c
Tourette Habit disorders
CBT by condition by hemisphere
F(1,11)=8.98; p<.05
The oddball effect (P300) for the motor task was significantly smaller over frontal areas and larger over parietal areas in TS and HD groups as compared to controls (Fig. 3a).
The frontal oddball effect is positively correlated with TS symptoms severity (TSGS global index). r=.38
The right hemisphere oddball effect significantly normalizes after CBT. This effect of CBT is larger with TS (fig. 3b) than with HD (fig. 3c)
Demographic and clinical data
TS (N=12)
HD (N=12)
Control (N=13)
ANOVA M σ p
Age (years)
39,7
13,7
33,8
12,9
37,9
10,1 ns
Laterality (% right hand) 92 75
100
Gender (% male) 17 38
0,010
Education (years) 16
4,6
2,6 15
2,7
Raven (prcentiles) 88
15,8 72
20,0 76
21,0
Anxiety BAI (pre) 7
6,3 13
6,2 2
2,3
0,000
Depression BDI (pre) 9
9,6 12
7,2
11,5
OCD-Padua (pre) 30
23,1 42
30,7 19
18,0
Independent t-test
Comparison between HD and Tourette
Global TSGS (pre) 20
8,6
6,5
Tics 11
5,0 6
2,4
0,004
Behaviour
6,1
5,5
OCD-Padua (post) 26
18,5
27,6
Depression BDI (post) 4
4,5
5,1
ns 
Anxiety BAI (post) 3
3,0 8
5,3
 0,010
Global TSGS (post) 10
8,1
7,7 Ns
4,1
1,5
0,020 5
6,6
Group x Condition x Region
(F(3,33) = 3,24; p<.05)
Non-motor oddball task
Fig Tourette group
Fig Habit disorders group
Frontal Parietal Frontal Parietal
4a b a b
P300
Fig. 6a
Fig. 6b
Tourette Habit disorders
Non-motor oddball effect
(Pre-CBT)
Fig. 6c
Clinical effects of CBT on TS and HD patients TS HD p*
BDI
0,01
0,05
BAI ns
OCD-Padua
TSGS
0,00
Tics
Behaviors
*Paired sample t-tests pre- and post-CBT
CBT by condition by hemisphere
F(1,11)=5,99; p<.05
The oddball effect (P300) for the non-motor task was significantly smaller over frontal areas in TS and HD groups than in the control group (fig. 6a)
The oddball effect tends to normalize after CBT. Consistently, this CBT effect is larger with TS than with HD (fig. 6b, 6c)
Group x Condition x Region
(F(6,66) = 0,67, p = ns)
Conclusions
CBT improved symptoms similarly in both clinical groups (50% improvement).
This clinical improvement tends to normalize the P300 oddball effect related to both types of tasks (motor and non-motor).
This treatment effect is present across tasks but is stronger during a motor oddball than a visual count task especially in the frontal region and in the right hemisphere.
Our results are consistent with a possible role of the prefrontal cortex and corpus callosum in mediating inter-hemispheric interference in TS, as demonstrated in previous studies (see Margolis et al., 2006; Plessen et al., 2007).
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