El Diario de Pontevedra : periódico liberal: Ano XV Número 4141 - 1898 maio 12

OBJECTIVE:Attention Deficit / Hyperactivity Disorder (ADHD) and Chronic Tic Disorder (CTD) are two common and frequently co-existing disorders, probably following an additive model. But this is not yet clear for the basic sensory function of colour processing sensitive to dopaminergic functioning in the retina and higher cognitive functions like attention and interference control. The latter two reflect important aspects for psychoeducation and behavioural treatment approaches. METHODS:Colour discrimination using the Farnsworth-Munsell 100-hue Test, sustained attention during the Frankfurt Attention Inventory (FAIR), and interference liability during Colour- and Counting-Stroop-Tests were assessed to further clarify the cognitive profile of the co-existence of ADHD and CTD. Altogether 69 children were classified into four groups: ADHD (N = 14), CTD (N = 20), ADHD+CTD (N = 20) and healthy Controls (N = 15) and compared in cognitive functioning in a 2×2-factorial statistical model. RESULTS:Difficulties with colour discrimination were associated with both ADHD and CTD factors following an additive model, but in ADHD these difficulties tended to be more pronounced on the blue-yellow axis. Attention problems were characteristic for ADHD but not CTD. Interference load was significant in both Colour- and Counting-Stroop-Tests and unrelated to colour discrimination. Compared to Controls, interference load in the Colour-Stroop was higher in pure ADHD and in pure CTD, but not in ADHD+CTD, following a sub-additive model. In contrast, interference load in the Counting-Stroop did not reveal ADHD or CTD effects. CONCLUSION:The co-existence of ADHD and CTD is characterized by additive as well as sub-additive performance impairments, suggesting that their co-existence may show simple additive characteristics of both disorders or a more complex interaction, depending on demand. The equivocal findings on interference control may indicate limited validity of the Stroop-Paradigm for clinical assessments

Sample description.

<p>Sample description.</p

Stroop-Task description.

<p>Items of Colour- and Counting-Stroop. Correct responses are “blue”, “yellow”, “green” and “red” for the Colour-Stroop and “3, “1”, “4” and “2” for the Counting-Stroop. Responses were given on a custom-made trapezoid four-choice response pad.</p

Colour discrimination and attention.

<p>The comorbidity of ADHD+CTD is characterized by additive effects on colour discrimination and attention. The Farnsworth-Munsell 100 hue colour discrimination test (above) revealed for ADHD and CTD additive effects on error scores (confidence intervals with p = .05) of the blue-yellow (left) and red-green (right) axis. Difficulties with sustained attention in the Frankfurt Attention Inventory as indicated by the number (FAIR-L, below left, confidence intervals with p = .05) and proportion (FAIR-Q, below right) of attentively processed items during the 6 min testing are present in children with ADHD but not CTD.</p

Congruency effects in the single-trial Stroop tasks.

<p>This Figure shows confidence intervals (p = .05) of the Congruency effects (as the respective differences in performance parameters between incongruent minus congruent conditions) from Colour- (left) and Counting-Stroop (right). Reaction-times were significantly slower in incongruent trials of both Stroop-Tests in all four groups (as the respective confidence intervals indicated by vertical bars around the respective mean do not include zero), and did not reveal any group-differences (as no mean lie outside the confidence intervals of comparison, see line A, above). Accuracy was significantly lower in incongruent trials of the Counting Stroop similarly for all groups (different from zero and negative in all groups, and all confidence intervals overlap with the respective means), but in the Colour Stroop interference liability on accuracy was present only in the pure ADHD and CTD groups, while Controls and children with ADHD+TIC did not show reduced accuracy in incongruent trials and showed less congruency effect as compared to both other groups (line B). The combined Speed-Accuracy parameter (line C, mean difference incongruent minus congruent trials of z-standardized reaction-time and accuracy scores) showed in the Colour Stroop (left) elevated interference load in the pure ADHD and pure CTD groups than in the controls and comorbid ADHD+TIC groups only, but no significant group differences in the Counting-Stroop (right).</p