Systematic review of the epidemiology of attention deficit hyperactivity disorder in Arab countries

Discussion

The prevalence of ADHD was investigated in different age categories among the Arab countries making it difficult to provide a reliable comparison between the countries. However, results of this systematic review shows that the prevalence of ADHD in Arab countries among schoolchildren aged 6-12 years ranges between 7.8-11.1%, while it was higher, at 16%, in the studies that included younger aged children between 3 and 15 years of age. Although this prevalence rate variability could be explained by the methodological differences, it is important to note that these prevalence estimates stratified by age are comparable in range reports in North America and Africa.6

Population prevalence studies of ADHD in the Arab countries were conducted mostly in schools, which facilitates access to participants; however, this may not reflect the prevalence of ADHD at the population level, as it might overlook a large number of children who are carrying the symptoms but are not enrolled in the schools or studying in schools for “special needs” children. Not including these children can lead to underestimation of the true burden of ADHD in Arab countries. Most studies reviewed were cross-sectional studies, which could account for the low number of predicted risk factors (gender and family history of psychiatric illness) (Table 1). Genetic causes that have been linked to the incidence of ADHD were not examined in the reviewed studies.

Results of a worldwide systematic review showed a large variability of the prevalence of ADHD.6 There review extracted information from 71 studies published from January 1997 to June 2007, and showed a prevalence ranging from 0.2-26.8%.6 This variation was explained mainly from methodological differences across the studies. The current review in Arab countries showed a similar level of variability across studies with prevalence ranges between 0.46-19.6%. Similar to this worldwide review, our review in Arab countries documented male predominance with a male to female ration ranging from 1.61:1 to 5:2.

Several explanations can account for the higher prevalence estimates found in a few studies in this review. The use of clinical interviews for children in Egypt,20 and the Self-Reported Questionnaire in Iraq between 2006 and 2012,26,38 as diagnostic tools, reported a prevalence of ranging between 14.75% and 19.6%. On the other hand, studies that used Conner’s Rating Scale for teachers, or parents, or both, show very similar estimates of prevalence ranging from 3.4% and 9.9%. Other studies yielded lower prevalence when using a different measurement tool. For example, the study conducted in Saudi Arabia by Alqahtani in 201016 used teachers and parents’ questionnaire and reported a prevalence of 2.7%. Other studies have examined the prevalence of ADHD among samples going under a general psychiatric evaluation for several mental and behavioral disorders,22,24,31 and resulted in the lowest prevalence’s of ADHD in Arab countries (1.3%, 0.9% and 0.46%) (Table 1). Eapen et al25 however, believed that the low rates of ADHD in both of their studies (the school and community samples in Al Ain study, UAE) were due to a culturally shared higher threshold for behavioral problems.

As reviewed by Gillberg et al in 2004,39 children and adolescents with ADHD show significant comorbidity with other psychiatric disorders, such as oppositional defiant disorder, conduct disorder, mood, and anxiety disorders, tic disorders, obsessive compulsive disorder, substance use disorders, as well as learning and language disorders. Four studies reviewed in this article found a similar pattern both in epidemiological and clinical samples.20,22-24 Biederman in 200541 and Barkley in 200538 reported on the impact of ADHD on poor school performance, career related outcomes, aggression, and financial crises. Our review also suggested similar findings to Arab countries.

With the increasing number of studies regarding ADHD in children and adolescents in Arab countries, there are still a small number of studies conducted in adult populations with most of them were limited by a small sample size.43 One of the studies addressing the issue of adult ADHD was carried out in Lebanon,37 but only as part of an international World Health Organization study, in which the prevalence of adult ADHD was estimated at 1.8%.44 The authors explained that the low rate of adult ADHD reported in this study was attributed to the use of a structural interview (associated with low rates), and respondents under-reporting their symptoms in interviews due to the stigma of mental illnesses in the Arab world. The second study that explored adult ADHD in the review was conducted on a sample size of 361 Iraqi college students with a mean age of 21 years old.28 The findings of the study showed a total prevalence of 16.6% with a significant indication of heavy nicotine intake (p=0.0001), a finding which has to be interpreted with caution due to its cross-sectional design, making it impossible to predict whether smoking was a risk factor or a consequence of ADHD.

Cultural factors may play a significant role in the identification of ADHD. Indeed, there may be a misperception in some Arab cultures for what is identified as a behavioral problem. Conversely, given that ADHD impairs academic performance, which is culturally highly valued in the Arab world, it may be specifically the inattention symptoms of ADHD (and not hyperactivity/impulsivity) that draws parents’ attention for early identification and treatment.42

We believe that the findings of this review have significant implications for health care planning as well as for service delivery and awareness campaigns in the Arab region. In many Arab countries, families may not accept their children’s mental health problems and their need for treatment for fear of labelling and stigma. It is important to fight stigma and increase awareness of child mental health, and ADHD in particular. Physicians also need to educate parents regarding symptoms of ADHD, possible causes or risk factors, and the importance of early intervention medically and behaviorally.

The negative impact of ADHD on adult’s daily-life performance was well investigated by Spencer et al in 2014.45 Researchers on Arab countries should consider looking into this area, which may contribute to form good medical practice regarding this issue, resulting in improvement in functioning with a positive investment on adults in Arab countries.

Several methodological issues need to be addressed. We limited our search to articles in this review those published in English, while articles in Arabic or French languages were not considered. Although most studies by research institutes and universities in the Arab world are published in English, we could have missed some articles, particularly articles in French (and not indexed in PubMed) from Morocco, Algeria, and Tunisia where most publications are in French, rather than the English language. In addition, our search was limited to publications in peer-reviewed journals, but not dissertations from Arab universities. However, we have searched local journals along with our PubMed search to be as inclusive as possible. Cross-referencing was also performed and no missed studies were identified.

In conclusion, the prevalence of ADHD in Arab countries is comparable with those reported in North America, Africa, and other countries of the Middle East. A significant association between ADHD and the following factors were reported in the Arab region: male gender, previous psychiatric illness in the family, vitamin D deficiency, poor school performance, sleep problems, and nocturnal enuresis. However, 20 out of the 22 studies retrieved were cross-sectional and thus, we cannot infer causality. Longitudinal studies are needed to investigate determinants and prognosis of this condition in the Arab world.