Electrophysiological measures and dual‐task performance in Tourette syndrome indicate deficient divided attention mechanisms

Abstract

Tourette syndrome has been associated with impairments of attentional functions such as distractability, even in subjects without co-morbid attention deficit hyperactivity disorder. Based on the results of earlier research we hypothesized that Tourette syndrome patients might employ altered control mechanisms of attentional processes and have concurrent difficulties in allocating their attentional resources among competing tasks. Event-related brain potentials (ERPs) were recorded in a group of Tourette syndrome patients and in a matched control group during a dual task experiment. This experiment required the simultaneous detection of visual and auditory target stimuli which were manipulated to yield two different difficulty levels each of which were varied orthogonally. The behavioural parameters confirmed the intended performance differences between difficult-to-detect targets and easy-to-detect targets. This was paralleled by lower amplitudes and longer latencies of the corresponding P3b-ERP subcomponents. Although Tourette syndrome patients were unimpaired in overall performance they showed an increased interference of visual task demands with auditory target perception. In parallel they also exhibited a reduced amplitude of the P3b component to auditory targets. The findings show that Tourette syndrome patients are not generally impaired in their dual task performance. The allocation of attentional resources to competing tasks however, is altered. We speculate that this may be related to deficient inhibitory functions.

Influence of comorbid obsessive-compulsive symptoms on brain event-related potentials in Gilles de la Tourette syndrome

“…Wolach and Pratt, 2001). In previous studies, a reduction in P300 amplitude has been consistently observed in GTS (Johannes et al, 1997(Johannes et al, , 2001b and in OCD (Kim et al, 2003;Miyata et al, 1998;Sanz et al, 2001;Towey et al, 1994), pointing towards a decrease in memory updating processes in both disorders. Nevertheless, these P300 patterns were elicited in slightly different experimental procedures, so nuancing homogeneous interpretation of their functional significance across groups.…”

“…Indeed, absence of P300 amplitude or latency differences in GTS (Johannes et al, 2001b(Johannes et al, , 2002van Woerkom et al, 1988) has been reported in earlier investigations, which could be ascribed to the influence of comorbid OCD in the sample of participants. Previous ERP studies either included GTS participants suffering from mild to severe OCS or provided no information about the presence of such symptoms in their sample.…”

Deep brain stimulation for psychiatric disorders: where we are now

“…207 Electrophysiological studies implicate overexcitability and dysregulation of frontal-subcortical circuitry resulting in deficiencies in processing of stimuli. 121,216,276,284 Histopathological and genomic studies provide evidence of structural alterations in the composition of inhibitory g-aminobutyric acidergic and cholinergic interneurons in the sensorimotor areas of the striatum and in the GP internus (GPi), suggesting an imbalance between inhibitor and excitatory regulation. 125,162 Evidence for neurotransmitter dysfunction has been shown in dopaminergic, 266 serotonergic, 301 cholinergic, 306 glutamatergic, 5 and intracellular second messenger transmission.…”

Neurocognitive Aspects of Tourette Syndrome and Related Disorders

“…This difficulty to inhibit interference could also rely on a problem of overfocused attention particularly salient in OCD (Savage et al, 1994). This hypothesis was confirmed in ERP research, where attention-related components peaked at a faster latency in OCD (Towey et al, 1990;Towey et al, 1993;Towey et al, 1994) than in a control group, which was not found with GTS (Johannes, Wieringa, Nager et al, 2001;Johannes et al, 2002;van Woerkom, Fortgens, Rompel-Martens, & Van de Wetering, 1988).…”

“…Other studies found larger N100 amplitude to both target and non-target stimuli, proposing that GTS patients allocate more attention than controls in processing both relevant and non relevant stimuli (van Woerkom, Roos, & van Dijk, 1994). However, recent findings with an auditory-visual oddball (Johannes, Wieringa, Nager et al, 2001), found a reduced amplitude of the P300 indicating an increased interference of visual task demands with auditory target perception, which suggested a deficit in cognitive control in GTS patients.…”