In this study, the age of the study group was selected from 6 to 12 years old. This was guided by studies in literature which studied behavioral problems and cognition in ADHD [22, 23].
This study showed that only 30% of cases had family history of ADHD. This is inconsistent with studies in many different countries, in which high heritability rates for ADHD was shown to be around 71–90% [24,25,26]. This can be explained by small sample size. Also, it is not an epidemiological study. It is worth noting that not all of the risk for ADHD is genetic, and estimates of heritability also include an element of gene environment interaction. It is estimated that between 10 to 40% of the variance associated with ADHD is accounted for environmental factors 
This study showed that 37.5% (N = 15) showed predominantly inattentive presentation (ADHD-PI) and 47.5 % (N = 19) showed combined presentation (ADHD-CT). This is in line with clinic samples prevalence but not with results in community prevalence. In clinic samples, ADHD-CT is approximately one and one half times more prevalent than ADHD-PI. Although predominantly inattentive type (ADHD-PI) appears to be more prevalent in the general population, children diagnosed with ADHD-CT are more likely to be referred for treatment probably reflecting the greater amount of disruptive behavior associated with the ADHD-CT symptoms .
This study showed that there was no significant difference between oxytocin levels in different ADHD subtypes (Table 2). This is inconsistent with Insel,  who found that among the ADHD subtypes, the ADHD-PI subtype had a significantly higher serum OT level than the ADHD-HI subtype. Demirci et al.,  also supported this and explained that reduced OT levels in the ADHD-HI subtype may cause high aggression and lower empathy in boys. This inconsistence may be explained by using salivary samples which may not reflect CNS OT levels and also, could be explained by small sample size.
There was significant difference between ADHD subtypes as regard the total number of correct responses (times the subject correctly selected the emotion anger and fear), where subjects with predominately hyperactive impulsive ADHD subtype (ADHD-HI) were the better performers, and subjects with combined presentation (ADHD-CT) were the worst (Table 3). This is in line with a study conducted by Kemp and Korkman,  who assessed emotion recognition using NEPSY-II and found that ADHD-CT performed significantly lower in affect recognition subtest. Also, consistent with meta-analysis study conducted by Bora and Pantelis,  who concluded that the most robust facial emotion recognition deficits were evident in anger and fear, yet they did not study them among different ADHD subtypes.
However, this is inconsistent with Yuill and Lyon,  who showed that impaired emotional processing in children with ADHD is unrelated to general cognitive limitations, such as impulsivity and inattentiveness, which affect the subtypes of ADHD . Also, this is inconsistent with the findings of Pelc et al.,  who found that children with the ADHD-HI subtype, in particular, make more mistakes in recognition of emotional facial expression; they particularly experience problems in recognizing facial expressions representing anger and sadness. Also, inconsistent with reports of Schwenck et al.,  who concluded that there was no difference among the ADHD subtypes with respect to recognition of emotions. This inconsistence may be explained by different methodologies in studies which were used to detect social cognitive domains. Tasks for the assessment of social cognition varied and included affective adult and child faces, timed or non-timed presentations, cross-matching tasks, matching faces to emotional stories and matching emotions to eyes, different social backgrounds, and socioeconomic status. Also, different age group among researches may be operative.
Hyperactive impulsive ADHD subtype was associated with rapid speed in detection of the emotions (surprise, disgust) (Figs. 1, 2 respectively). This finding is closely related to findings of a study that examined visual and auditory emotion recognition in a wide scale of children and adolescents with ADHD which was conducted by Waddington et al., . The latter study showed that speed of visual and auditory emotion recognition was positively correlated with hyperactivity and inattention on Conner’s parent rating scale, and speed of auditory emotion recognition positively correlated with inattention on the Conner’s teacher rating scale; however, the latter study did not specify each emotion separately. A study conducted by Tehrani-Doost et al.,  found that the time spent in recognizing happy faces was higher in the ADHD group; however, the relation between the time needed to detect the emotion and different ADHD was not studied in this research. However, these study results are expected as patients with ADHD hyperactive impulsive subtype are characterized by being reluctant in doing effort and usually make rapid and impulsive decisions. This inconsistence may be due to the different methodologies and different assessment settings.
There was no correlation between subtypes of ADHD and the total number of correct responses of emotions (happiness, sadness, fear, anger, surprise, and disgust) (Table 4). These findings were inconsistent with that of the study conducted by Tehrani-Doost et al.,  which showed that inattention associated with a considerable effect on detection of both angry and sad targets, also found significant negative association of hyperactivity-impulsivity with anger detection. Another study showed that hyperactivity measures were positively correlated with the recognition of disgust and inversely correlated with the recognition of fear . This inconsistence may be due to small sample size and using only one task for assessment of social cognition (emotion recognition) in which only one social cognitive domain was assessed.
In this study, the earlier onset was associated with more errors in anger detection (Fig. 3) yet less errors in surprise detection (Fig. 4). A meta-analysis conducted by Bora and Pantelis,  showed that social cognitive deficits in emotion recognition and theory of mind (ToM) were very subtle and non-significant respectively in adults with ADHD. There is some evidence that aspects of social cognition like affect perception deficits are present in younger but not older patients with ADHD. In an early study by Shapiro et al., , the author concluded that this finding reflects a developmental improvement in allocation of attention resources or the implementation of compensatory strategies to cope with the emotion perception deficit; this was also supported by Guyer et al.,  who did not yield significant affect recognition deficits in patients aged 12 or older. This is inconsistent with Waddington et al.,  who found that older patients with ADHD unexpectedly showed poorer emotion recognition than children with ADHD.
This study showed that there was significant positive correlation between salivary OT levels and total hits (correct responses) of the emotion happiness; also, there was significant negative correlation between salivary OT levels and total hits fear (correct responses) (Table 5). In a study conducted by Feeser et al., , the administration of intranasal OT improved recognition of avoidance-related facial expressions of emotions (fear, sadness, and disgust) but had no effect on approach-related expressions of emotion (happy, angry, and surprise). In other studies, OT improves only specific emotions such as facial expressions of happiness , fear , or anger , which may conclude the possible relation between OT level and emotion recognition.
Examination of different age groups, males, females, and interventional studies in a large sample may be helpful in accurate assessment of this relation and its role in improvement of ADHD deficits.
This study was based on sample size calculation so results constitute statistical power. Including only boys to reduce the impact of estrogen on social cognition and OT level lessened confounding factors. Using a well-validated tool to measure social cognition which is used to assess multiple dimensions of affect recognition including reaction time, correct responses, incorrect responses, and assessment of secondary emotions, such as surprise, and positive emotions, such as happiness, also, it was interesting for the participants being iPad application.
The use of cross-sectional studies can prevent drawing conclusions about causal relationships. Reliance on only semi-structured clinical interview without using standardized structured diagnostic tool may affect diagnosis; also, comorbid conditions may be missed; this can affect our results as many other psychiatric conditions can affect social cognition and OT level. Using salivary OT rather than cerebrospinal fluid (CSF) might not have completely reflected OT action in the CNS because the relationship between peripheral and central levels of OT is unclear.