الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 170 |  |  |
| | | from | 170 | | |
Abstract
ASD incidence has increased in the last decades worldwide. Globally, the prevalence of ASD was 62/10000 in 2012. As for the Arab world, the prevalence of ASD in UAE was 29 per 10,000 native children. In Saudi Arabia the prevalence of autism was 18 cases every /10,000 children. In Egypt, there is no accurate data about the prevalence of ASD among children, but it was estimated that about half million children in 2008 were expected to have ASD, which meant that 67 children were suffering from ASD every 10000 people.
Arab world prevalence of ASD may be under estimated due to difficulty in the diagnosis of ASD, and culture of the community which prefer to keep the children in the ordinary schools rather than being referred to special schools.
ASD is caused by genetic and environmental interaction that affecting early brain development. Risk factors of ASD can be divided into environmental risk factors and other factors. These factors can affect pregnant woman, the lactating mother, and/or the young child.
Environmental risk factors include environmental chemicals such as heavy metals, persistent organic pollutants, air pollution. Heavy metals (lead, mercury, arsenic and cadmium) are neurotoxic agents that can affect the brain of the fetus or the child. Heavy metals levels were found to be higher in blood and hair of the autistic children than in the non autistic ones, this may suggest an abnormal metabolism and excretion of these metals in ASD children.
Other environmental factors include occupational hazards, bad life style habits (alcohol intake, tobacco smoke, ETS exposure), infections during pregnancy or in early childhood, drugs (prenatal exposure to misoprostol, valproic acid), dietary factors (vitamin D deficiency, folic acid deficiency) and electromagnetic radiation exposure.
Other risk factors include pregnancy and delivery complications as abnormal presentation of delivery, low Apgar score at 5 minutes, pre-term labor (age at birth < 35 weeks), umbilical-cord complications, fetal distress, low birth weight, preeclampsia, diabetes mellitus, congenital malformation, meconium aspiration, blood group or Rh incompatibility, and hyperbilirubinemia. Psychological diseases and advanced age of parents can also increase the risk of ASD. Males are affected by the disorder more than females.
The present study aimed at assessing the relation between the exposure to environmental risk factors and ASD among children in Alexandria. To reach this aim, a case-control study was conducted in the outpatient clinics of El Shatby Hospital, University of Alexandria in Alexandria Governorate and the central laboratory of High Institute of Public Health (HIPH), University of Alexandria.
Cases were selected to be children with ASD aged from three to eight years old attending the outpatient neurology pediatric clinic in El Shatby Hospital with ASD, according to DSM-5 criteria. Control group was children without ASD that attended other pediatric clinics. Exclusion criteria were physically handicapped children and children with liver or renal diseases. Both cases and controls were matched on age and sex.
Summary
112
The sample size was one hundred children; fifty per group. A structured interview with a pre-designed questionnaire was applied to care givers and was utilized to collect data from the cases and controls. The data included personal and Socio-demographic data; medical, obstetric, and current pregnancy data; parental occupation and occupational hazardous exposure data; life style and food consumption data of mother; data about exposure to different indoor and outdoor environmental risk factors; data about medical history of father; data about the life style of the child.
Apart from that, severity of the ASD was estimated using Child Autism Rating Scale (CARS) Arabic version. Also, sensory profile assessment of the children was done by using Short Sensory Profile test in order to assess the relation between the severity of ASD and sensory profile.
Lastly, as lead and mercury are important environmental risk factors for ASD, all participants were tested for hair lead and mercury concentrations. The hair lead and mercury contents were measured using Atomic Absorption Spectrophotometer after wet digestion of the hair.
Appropriate statistical procedures were applied to handle the data, so the following results were found: 1- Concerning mercury concentration in hair, children with hair mercury level ≥ 0.41 µg/g hair revealed significant risk for ASD (OR=9.33; 95% CI: 3.72-23.42) compared to those with hair mercury level < 0.41 µg/g hair. Children had hair level from 0.50 µg/g hair to less than 0.75 µg/g hair and ≥ 0.75 µg/g hair had 5.04 and 25.67 times more risk to develop ASD in comparison with children had hair level < 0.25 µg/g hair and the risks for these upper two categories were statistically significant (95% CI: 1.04-24.19; 95% CI: 4.42-149.00 respectively). The observed increased trend was found to be statistically significant (X2 trend for Odds= 20.76, p value for Odds =0.001). 2- As regards lead concentration in hair, a statistically significant high risk of ASD in relation to hair lead level ≥ 2.71 µg/g hair was calculated (OR=8.14; 95% CI: 3.32-19.94) compared to those with hair lead level < 2.71 µg/g hair. Children had hair level from 2 µg/g hair to less than 4 µg/g hair had 4.59 times more risk to develop ASD in comparison with children had hair level < 2 µg/g hair (95% CI: 1.52-13-90). The risk for ASD associated with hair lead levels ≥ 4 µg/g hair was very high and statistically significant (OR=18.67; 95% CI: 3.82-91.17). A statistically significant trend was computed (X2 trend for Odds =14.96, p value for Odds =0.001) telling that the more the increase in hair lead level, the more the chance of ASD. 3- Regarding child exposure to TV within first two years of age, elevated risk of ASD was calculated. TV watching produced statistically significant high risk for ASD (OR=5.41; 95% CI: 1.66-17.65). The risk for TV watching rose with the increased frequency of watching TV. In the uppermost exposure category to TV (≥5 hours per day) the risk for ASD was very high (OR=10.00; 95% CI: 2.6837.38). The trend of risk was also significant (X2 for trend=15.01, p=0.001).
Summary
113
4- With respect to maternal age during pregnancy of the child in the study, Mothers with age forty years or more were 5.25 times more prone (95% CI: 1.00-27.45) to have ASD children than mothers with age less than 30 years. A significant trend in risk was observed with the increase in mother’s age (X2 for trend was 5.90; p=0.02). In conclusion, the risk of ASD increased with increasing age of parents. 5- Concerning pregnancy related problems, mothers suffered from these problems, like inadequate weight gain, gestational diabetes and threatened abortion, had a significant risk to deliver children affected by ASD (OR=4.94; 95% CI: 1.9912.26). A significant trend in risk of ASD (X2=11.38, p = 0.001) was observed in relation to the problems encountered during pregnancy. Mother suffered from one problem had 4.27 times more risk (95% CI: 1.63-11.18) to had ASD child. The risk increased if the mother suffered from two or more problems (OR=10.25; 95% CI: 1.16-90.33). There was a risk for each problem but the risk was not significant. 6- Regarding father age of the child in the study (during conception period), In comparison to fathers with age less than 30 years, forty years old fathers or more were about four times more likely (95% CI: 1.20-13.62) to have ASD children. A significant trend for risk was computed in relation to the increase in father’s age (X2 for trend was 5.37; p=0.02). 7- Regarding neonatal problems, neonatal prolonged/severe jaundice increased the risk of ASD (OR=6.00; 95% CI: 1.24-28.99). Neonatal respiratory problems led to increased risk for ASD by about three and half times (OR= 3.63; 95% CI: 1.08-12.18). 8- Mothers delivered their babies by caesarian section (CS) had about three and half times more risk (OR= 3.45; 95% CI: 1.52-7.85) to had children suffering from ASD than those delivered by normal vaginal delivery. 9- With regard to exposure to severe infections, during first year of life, experience of severe infection raised risk of ASD significantly by two and half folds (OR=2.49; 95% CI; 1.06-5.86). Significant risk was computed for exposure of severe infection during second year of life also, with odds ratio of 3.16 (95% CI: 1.03-9.69). As for exposure to infections that required admission to hospital during first two years collectively, statistically significant risk for ASD was found (OR=3.08; 95% CI: 1.33-7.15). 10- Anemia of the mother made her child had about three times more risk (OR= 3.04; 95% CI: 1.21-7.60) to develop ASD. 11- Maternal exposure to tobacco smoke during pregnancy from her husband had a significant risk for ASD of sibling of 2.79 (95% CI: 1.21-6.39). In addition to that, the more the father smoked the higher is the risk. In comparison with nonsmokers, light, moderate and heavy smokers had a risk of 2, 4 and 5.25 times respectively of having ASD children. A significant trend in risk (X2 for trend=6.87, p=0.01) was noticed with the increased smoking. Regarding allowance of smoking inside home, the risk was also high and significant (OR=4.21; 95% CI: 1.69-10.45) among those allowed smoking inside their houses of having ASD offspring in comparison with those living in smoke free home.
Summary
114
12- Mother suffered from common cold or sore throat during pregnancy was associated with a significant risk of ASD for offspring (OR=2.26; 95% CI: 1.015.05).
Finally, the study showed that: 1- Eighty percent of cases had mild to moderate ASD (calculated by CARS test) while the other 20 % of cases suffered from severe ASD. 2- There is positive, intermediate and significant correlation between lead levels in hair of children (in microgram/g hair) and severity of ASD (by the total score of CARS) (r = + 0.375; p= 0.007). 3- The correlation between mercury levels in hair of children (in microgram/g hair) and severity of ASD (by the total score of CARS) is positive, intermediate and significant (r = + 0.464; p= 0.001). 4- As for sensory profile, forty five percent of the sample size had typical sensory performance while 24 % had probable difference from normal pattern. The majority of cases (60 %) revealed definite difference in sensory profile from normal pattern and only 4 % exhibited typical performance. Pearson’s correlation between severity of ASD (by the total score of CARS) and sensory condition according to sensory profile was negative, intermediate (r = - 0.530) and highly significant (p=0.001); i.e. with the increase in CARS score (increase severity of ASD) the sensory profile score declines (sensory profile becomes worse).
The results from the present study made the following recommendations important to be implemented: • Persons should be aware about the environmental pollutants and the ways to protect their health especially pregnant women and children. • Increase the awareness of health care providers about environmental risk factors and its effects on the physical condition of each person, so they can pick up high risk children and pregnant women and advice parents about the ways of reduction of exposed to environmental hazards • New epidemiologic studies should explore the association between environmental factors and ASD in Egypt are needed. They should use biological markers. They should search for gen-environment interaction. The researches should focus on better understanding of how the social and psychological factors in Egypt contribute to the pathophysiology of ASD. • New studies should be implemented to establish a new cut off points of lead and mercury in the human body above which one should act to reduce their levels before the appearance of obvious side effects. • Screening for lead and mercury in maternal blood should be part of prenatal routine investigations to identify women at high risk and provide suitable management for them. • Children with abnormal delayed milestones should be investigated thoroughly and lead and mercury levels in their body should be evaluated.
Summary
115
• A comprehensive approach to the complex environmental problems in Alexandria especially the problem of air and water pollution which need modification of the currently established policy measures to improve air and water quality • Strict implementation of laws that enforce factories to put filters to improve air quality near industrial areas. • Establishing strong legal framework and implementation of these laws on air and water pollution.
In conclusion, as the incidence of ASD is increasing and the style of life of the family after getting a child with ASD is changed and the expensive prolonged management of ASD which has a huge burden on the family and society, hence, efforts should be gathered to decrease incidence of ASD and holistic strategies should be taken to control its risk factors.