The first and most important step in the prevention and management of MHP is to find the extent of these problems in children and adolescents at the community level. In the current study the parent-rated SDQ was used to assess MHP in a representative sample of children and adolescents. The Persian version of SDQ had already been validated in the Iranian population (
6,
7), and its reliability as a psychometric tool demonstrated in several population based studies (
4,
5). The present study assessed SDQ data set obtained from 1200 primary school children aged 6 - 12 years old. The findings revealed that the proportion of children with a high risk of MHP was 9.6%, and for those with a borderline risk, 9.7%. Several factors including male gender, physical health problems in family members, housewife mothers, low educated mothers, unemployed and low educated fathers, and low family income were marginally associated with a higher chance of occurrence of MHP in children and adolescents. The study showed that based on parent report SDQ, 9.6% of children had total scores above 17, and that among these, peer problems were the most frequent difficulty. These findings are considerably lower than those of a similar Iranian study conducted 4 years earlier in Tehran (
8) in which the total SDQ score of 25.8% of children in the same age range was higher than 17. In the Tehran study conduct problem was the most frequent problem, followed by peer problems (
8). This rate was 26% in Arman’s study carried out in Isfahan using the same research tools and method (
9). Isfahan’s study showed conduct problems and peer problems to be the most frequent difficulties in children (
9). The result of the present study was in agreement with those of several European studies which used the same tool. The proportion of children classified as borderline or abnormal based on parent rated SDQ has been 18.5% in 3 - 17 year-old German children (
10) which is consistent with the result of our study (19.3%). In a comparative study in the UK the frequency of MHP in white British children and refugee children was 15% and 27%, respectively (
11); while in another study using ICD 10 diagnostic criteria, 10% of British children and adolescents aged 5 - 15 suffered from MHP (
12). In the BELLA study (
13) performed on a large population in Germany using SDQ, 16.1% of 7 - 11 year-olds scored above the normal range (borderline or abnormal score) which is slightly lower than our result (19.3%). In Nordic countries the frequency of MHP according to SDQ parent-report has been much lower than in other countries, ranging between 5.7% and 7.2% (
14). Among other countries of the region, 34.4% of children aged 5 - 11 in Pakistan (
15) have scored higher than borderline (total score > 17). This rate has been 14% in Arab children in the Gaza strip (
16); with both of these being much higher than that of the present study in Iran (9.6%). In a study on 3 - 17 year-old children in China, 21% of children scored higher than normal (8.9% borderline and 12.1% abnormal) (
17). The present study revealed the prevalence of MHP in children in an Iranian urban community sample to be less than Pakistan, China and Gaza strip; and higher than England, Germany and the Nordic countries. These findings predictably reflect such differences as socioeconomic and cultural parameters, as well as in the availability and extent of mental health care in these countries. The most frequent problem in the present study was peer problems followed by hyperactivity problems; while in certain other countries such as the Nordic countries, Britain and China it was hyperactivity problems followed by emotional problems, and in Germany, conduct problems. In our study boys scored higher than girls in all SDQ subscales, which is in agreement with the results of similar studies in Britain, Germany, Denmark, China and Pakistan, demonstrating that boys are at a higher risk of MHP compared to girls. With regard to the impact of MHP on various aspects of children and their families’ life, 68.4% of children had an abnormal impact score. Despite scoring very high in the impact supplement, many of these children were not identified by SDQ screening and their total score did not indicate a mental health problem (scored less than 13). The rate of abnormal impact score was higher in girls than in boys. Although 13.3% of boys had an abnormal total SDQ score, 65% of them had abnormal impact scores. Interestingly however; although total SDQ score in girls was abnormal in 5.6% of girls, 72% of them had abnormal impact scores. The impact score in our study was much higher than those of other countries. In the BELLA study 12% of children with abnormal impact score were found to have normal SDQ total score (
18). In the Copenhagen cohort study, only 4.8% of children had an abnormal impact score (
19), while a screening for psychopathology in child welfare in Belgium showed that 49% of children in child welfare had an abnormal impact score (
20); which is still less than the rate in our study. In developed countries, the extensive state support of families who have children with MHP is likely to reduce the burden caused by these problems and can explain the lower rate of impact compared to developing countries like Iran. The high rate of children with abnormal impact scores in our study may also reflect the significant sensitivity of parents toward their children’s feelings and behavior. Some children had abnormal scores in only a few items, but their parents reported a high or very high impact of the reported problems on educational and social aspects of the children’s life. Although the proportion of girls who had abnormal total SDQ scores was approximately less than half of the boys with abnormal total score (5.6% compared to 13.3%), the percentage of families who were affected by these problems was higher in girls than in boys (72% compared to 65%).This reflects the greater sensitivity of parents toward their daughters’ behavioral and emotional problems as compared to their sons’; a finding which is culturally justifiable in most Iranian families. Likewise, psychiatric problems in girls may be more likely to cause personal distress, emotional expression and family impairment compared to boys. Among participants in the study, 2.9% of children had a previously diagnosed mental health problem. According to the parent report version of SDQ 19.3% of participants scored above the normal threshold. There was a significant association between having a diagnosed mental health problem and abnormal SDQ total score (OR = 11.11, 95% CI = 5.55 - 25.00, P < 0.001) which further underpins the validity of SDQ. Other variables significantly associated with abnormal total score of SDQ in simple marginal analyses were: male gender, physical health problems in family members, low level of mother and father’s education, housewife mothers, unemployed fathers, and low family income. Some of these correlations are in line with other studies. In the Copenhagen study (
19) the prevalence of MHP was higher among children with low level of maternal education. This finding was also reported in a prevalence study in Italy (
21). The results of the study by Arman et al. showed that abnormal SDQ total scores in adolescents were associated with lower level of education in both mothers and fathers (
9). Low family income has been correlated with a higher risk of MHP in all these three surveys, which is well-matched with our results. In another prevalence study in Great Britain (
12) the rate of MHP was greater among children of parents without educational qualifications than highly educated parents (15% vs. 6%) and in families with neither parent working, compared to both parents being at work (20% vs. 8%). All of these findings are in line with the results of the present study. The fact that parents with low level of education are likely to have a lesser degree of knowledge, and hence overall insight about dealing with their children’s behavioral and emotional problems, can largely explain this correlation. Great levels of emotional and behavioral problems were reported in our study in children of unemployed fathers and also parents who spent less time with their children. Although unemployed fathers may spend more hours with their children, financial problems and low self-confidence arising from unemployment usually can interfere with having a good relationship with children. These findings underpin the fact that social and economic disadvantages can increase the risk of MHP in children and adolescents.