Visual Attention Deficits Contribute to Impaired Facial Emotion Recognition in Boys with Attention Deficit/Hyperactivity Disorder

Sir,

I applaud Shin and his co-authors for their recently interesting published study regarding visual attention deficit and facial emotion recognition in boys with ADHD (Neuropediatrics 2008; 39: 323–327) [8]. The study compared “emotion recognition” (ER) and “contextual understanding” (CU) between ADHD children and a control group. The children looked at some facial expressions and they recognized if the picture is a positive or negative emotion. The ability of children to recognize positive and negative emotion was assessed by ER. Then, they looked to four cartoons displayed on a monitor. The children should select the appropriate cartoon with the facial expression that was displayed on monitor. It was hypothesized that attention deficit is responsible for errors in facial emotion processing in ADHD. The study concluded that attention deficits account for the deficit in recognition of facial expressions of emotion.

The study and its results can be viewed from another aspect and some issues should be reviewed. First, the study is a cross-sectional study. The statistical analysis was conducted using t-test, Mann-Whitney U test, chi-square test, and linear regression analysis. These tests examine possible associations. So, it needs to be more discussed if it can be concluded that one variable is responsible for another one. An association is a bidirectional factor. Can CU impairment cause impairment of attention? (Vice versa to what was concluded).

Second, ER scores of positive and negative emotions were not different between the two groups of ADHD children and the control group. It may not support that emotion recognition is impaired in ADHD children. In addition, only age was in association with a negative emotion score. In other words, if I correctly understood, linear regressions did not indicate that ADS is in association with positive or negative ER score. The ADS of omission was in association with CU score in ADHD children. It may show that ADHD children have difficulty in matching facial emotion to some contexts or situations [14]. It might be somewhat different with the titles that they have impaired facial emotion recognition.

With consideration that the CU score was different between the two groups while the ER scores were not different between the two groups, further studies should investigate whether ER is impaired or if a working memory (sustained attention) impairment caused the impaired matching of emotion and context.

Of course, the absence of evidence does not support evidence of absence [1]. It is worth mentioning that many studies indicated that facial affect recognition is impaired in ADHD children [2] [3] [9] [10]. The lack of a difference between the two groups regarding ER can indicate that ADHD children perceive facial emotion expression the same as the control group. It is not in a similar line with the results of the above-mentioned studies. Of course, a study on adults with ADHD reported that impaired facial recognition is not related to gross perceptual processes [6]. Probably, as the authors mentioned, further studies with more sample size should be conducted to survey if the perception of ADHD children is not different from that of control groups.

Moreover, ADHD is not a homogeneous disorder. There is an argument that ADHD subtypes may be distinct disorders [6] [12]. For example, the inattentive type of ADHD may be co-morbid with anxiety problems more than the other types [13]. Considering ADHD subtypes in future studies could be helpful for comparing the results of different studies.

Learning disorder is a common co-morbid psychiatric disorder in children with ADHD [5] and it may be in association with an impairment of information processing. Some types of learning problems are in association with a deficit in visual processing [5]. So, further studies should consider LD as a covariant factor.

Finally, there is a speculation that emotion regulation of ADHD children might be impaired [4] [11]. ADS predicted a negative emotion score, not a positive emotion score. It needs to be more discussed if the association is due to an attention deficit or an emotion processing or a motivational deficit.

A. Ghanizadeh

References

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Correspondence