The Role of Environmental Factors in Etiology of Attention- Deficit Hyperactivity Disorder

Environmental factors in etiology of ADHD Attention deficit and hyperactivity disorder (ADHD) is one of the most common developmental disorders of childhood. It was reported that it is a disease that affects 5.29% of children and adolescents in the entire world. Although ADHD is a disorder with high inheritability, genetic factors are not the only explanation to ADHD etiology. ADHD is a disorder etiology which has genetic and environmental components and gene-environment interaction. In spite of the fact that many environmental factors are linked to ADHD, the number of environmental factors that are proven to be in significant cause-effect relation is too small. In other words, in presence of proper genetic basis, disease appears in presence of many environmental factors each of which have a slight effect, its severity or prognosis is variable. Environmental factors that are most commonly linked to ADHD pathophysiology are; complications during pregnancy, natal and postnatal period, several toxins and food substances. It has been considered that exposure to risk factors that may affect development of the brain in any of these periods will have long-term effects on behavior. Along with mother’s cigarette or alcohol use during pregnancy, emotional difficulties, medical diseases and complications of pregnancy; natal complications, low birth weight, premature birth, post mature birth, physical traumas that may affect brain development in early childhood, psychosocial difficulties are also found to be related to ADHD. Studies of gene-environment interaction also note the importance of environmental factors. For example, a study showed that in cases which carry 7 repeated alleles of DRD4, exposure to prenatal cigarettes causes more severe symptoms of ADHD. The purpose of this paper is to evaluate the role of environmental factors in etiology of ADHD, review these factors in the light of related literature and, lastly, to mention gene-environment interaction

The Elements, Lawrence University Flute Ensemble, January 30, 2017

Harper Hal

Candidate Gene Studies of Attention Deficit Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is a common psychiatric condition that affects approximately 5-10% of children worldwide. This disorder is defined by a combination of symptoms of inattention and hyperactivity/impulsivity. Although twin studies demonstrate that ADHD is a highly heritable condition, molecular genetic studies suggest that the genetic architecture of ADHD is complex. Molecular genetic studies support the thesis that dopaminergic, serotonergic, and noradrenergic neurotransmission pathways account for the etiology of this complex disease. This article reviews the latest findings on the molecular genetics of ADHD

A Comparison of Obsessive Compulsive Disorder, Pervasive Developmental Disorder, and Control Groups in Terms of 2D:4D Ratio and Finger Lengths

Objective: Obsessive compulsive disorder (OCD) and autism share some common features, such as repetitive behaviors. Second finger to fourth finger ratio (2d: 4d) is thought to be associated with prenatal androgen exposure and differs between the sexes and 2d:4d ratio is reported to be more "masculine like features" in autism. The aim of this study is to compare OCD and autism that display common features in terms of 2d: 4d ratio and finger lengths. Methods: This study included 15 boys diagnosed with OCD, 12 boys diagnosed with Pervasive Developmental Disorder (PDD), and 54 healthy boys with no psychiatric disorders between the ages of 6 and 18 years. The diagnoses of OCD and PDD were reached after detailed clinical evaluations according to DSM IV-TR criteria. After the evaluation, the children's and adolescents' hand length, hand width, and finger lengths were measured with a digital compass. Results: In this study, we found no statistically significant difference between the control, OCD, and PDD groups regarding the right and left 2d: 4d ratio. Whereas in the PDD group, we found that the right hand second and third fingers and the left hand second, third, and fourth fingers were shorter than the fingers of those in the control group. We also found that left hand length was shorter in the PDD group than in the OCD group and the second finger of the right hand and third finger of left hand was shorter in the PDD group than in the OCD and control groups. Conclusion: In this study, we did not observe any differences between the OCD, PDD, and control groups in terms of 2d: 4d ratio; however, we found that that some finger lengths were shorter in the PDD group than in the control group. This result may be a dysmorphological sign that could be screened in the PDD group, but we need further research with larger sample sizes to confirm its significance

Prevalence and risk factors of monosymptomatic nocturnal enuresis in Turkish children

Objectives : To determine the prevalence of primary monosymptomatic nocturnal enuresis (PMNE) and assess risk factors that can cause this disease. Methods : After the determination of 15 primary schools in the provincial center of Ankara, questionnaires were given to 15,150 students to be answered by their parents. Detailed urologic history was obtained and physical examination applied to the students whose parents answered the questionnaire. After excluding children with polysymptomatic NE, 14060 questionnaires of MNE patients were evaluated. Demographic features with social and medical history of students and their parents, general approach of family to the children, school success of the students and general behavioral attitudes, method of toilet training and the presence of nocturnal enuresis were questioned. Results : MNE was determined in 9.0% (n: 1266) of the students and nocturnal enuresis frequency was higher in boys than girls (P< 0.05). Univariate analysis revealed gender, method of toilet training, sleep problems, school success, and general approach of the family to children and general behavioral attitudes of the children as significant factors. In logistic regression analysis; age, male gender, toilette training with threatening method, deep sleeper, sleep walking, being introverted and shy, significantly increases the risk of nocturnal enuresis. Conclusions : The current study suggests that the methods of toilet training are extremely important to prevent bedwetting and behavioral disorders due to enuresis. Parents should be well-informed about the appropriate toilet training method

Determination of Serum Vascular Endothelial Growth Factor Levels in Attention Deficit Hyperactivity Disorder: A Case Control Study

Objective: The effect of vascular endothelial growth factor (VEGF) on neuronal development is known, but its relationship with attention deficit hyperactivity disorder (ADHD), a neurodevelopmental disorder, has not yet been fully elucidated. To our knowledge, this is the first human study investigating serum VEGF levels in ADHD patients. In this study, it has been aimed to compare serum VEGF levels between a healthy control group and in ADHD patients to help determine the association between serum VEGF levels and ADHD. Methods: This study sample included forty-four patients diagnosed with ADHD and 43 healthy volunteer controls between 7 to 14 years old. Blood samples were taken from patients and the healthy control group to assess their serum VEGF levels. VEGF levels were calculated by subjecting the optical densities of the samples to concentrations of known standards as provided in the ELISA kit and then performing a regression correlation analysis. Results: The mean VEGF level of the children was 333.6 +/- 209.8 in the ADHD group and 341.3 +/- 201.8 in the control group. There were no statistically significant differences in serum VEGF levels between the ADHD and control groups (U = 926.000, z = -0.170, p = 0.865). Conclusion: There was no significant difference in serum VEGF levels for untreated ADHD cases and a healthy control group. This is the first human study investigating serum VEGF levels in ADHD patients, so there is a need to replicate these findings