Post-traumatic stress disorder Examining the levels of BDNF and cortisol in children and adolescent victims of sexual abuse

摘要

INTRODUCTION: Glucocorticoids act through glucocorticoid receptors (GR) found in high concentrations in the amygdala and the hippocampus. In GR-mediated molecular activation, the brain-derived neurotropic factor (BDNF)-mediated signal pathway is required for memory consolidation. BDNF expression in the central nervous system is modified by various brain traumas including stress, ischemia, epileptic seizures, and hypoglycemia. Glucocorticoids play a role in the regulation of BDNF. In the rat hippocampus, stimulation of mineralocorticoid receptors (MR) increases the level of BDNF, while stimulation of glucocorticoid receptors (GR) decreases the BDNF levels1. As mentioned above, trauma affects growth factors and the HPA axis. There are limited studies in the literature that have investigated the relationship between cortisol and BDNF levels in child and adolescent victims of sexual abuse. The present study compares the levels of BDNF, cortisol, and ACTH between child and adolescent victims of sexual abuse with those who have no trauma history. METHOD: Study Sample: The study was conducted in the Department of Child Psychiatry at Dicle University. The study included a total of 44 children (M/F: 12/32) between the ages of 8 and 17 years who had experienced child sexual abuse and 42 age- and gender-matched children (M/F: 12/30) as control group. The study data were collected between December 2011 and April 2012. Children who achieved an intelligence score below 70 points, who had significant neurological or medical disorders, who received oral contraceptives, had previous or current cortisol therapy, vitamins, and those who showed morbid obesity or active infection were excluded in order to prevent interference with the biochemical parameters. The patients were evaluated by two psychiatrists. The parents provided informed consent in order for their children to participate in the study. Approval for the study was obtained from the Non-Interventional Clinical Research Ethics Committee at Dicle University Faculty of Medicine. Sociodemographic features of the participants were obtained and a clinical data form was completed. This was followed by collection of a 2 ml venous blood sample for biochemical tests. Sociodemographic Data and Clinical Data Form: This form included questions about age, gender, education level, age of the parents, number of siblings, history of psychiatric disorders or substance abuse in the relatives, height, weight, and body mass index (BMI), type of abuse, duration and frequency of abuse, relationship with the abuser, and abuse history. Biochemical Analysis: The blood samples were obtained in the morning between 10:00 and 12:00 AM. Cortisol, ACTH, and BDNF levels were evaluated using the ELISA. Statistical Analysis: The statistical analysis was performed using SPSS 15.0 software package. A p-value below 0.05 was considered statistically significant. RESULTS: The mean age was 13.1±2.7 years (range: 8-17 years) among the victims of sexual abuse. In the control group, the mean age was 13.8±2.9 years (range: 8-17 years). The sexual abuse group consisted of 12 males and 32 females, and the control group consisted of 12 males and 30 females. The duration of education was lower and the mean number of siblings was higher in the victims of sexual abuse and their parents compared to the control group (p=0.02, p0.05). There was no significant difference between the groups in terms of height, weight, and BMI (p>0.05). Regarding the parameters related to sexual abuse, 64% (n=28) of the victims had experienced sexual abuse involving penetration. Of the victims, 52% (n=23) had experienced a single assault and 48% (n=21) multiple assaults. 23% (n=10) had experienced sexual abuse within the family (incestuous) and 77% (n=34) sexual abuse committed by non-related persons. Of all cases, 82% (n=36) were smokers and 18% (n=8) were non-smokers. Cortisol levels were significantly higher in the sexual abuse group compared to the control group (p<0.001). Albeit statistically insignificant, ACTH levels were higher in the sexual abuse group compared to the control group (p=0.10). Consistent with these findings, the ACTH/Cortisol ratio was lower (p<0.001). BDNF levels were significantly lower in the sexual abuse group compared to the control group (p=0.04). The mean time that elapsed from the first sexual abuse until the date of examination was 22.72±21.72 months (range: 2-120 months). The evaluation of the relationship between this time span and cortisol levels revealed that cortisol levels decreased as this time interval increased (r=-0.271, p=0.03). In the sexual abuse group, there was no relationship between the presence of penetration and cortisol, ACTH, and BDNF levels. Cortisol and BDNF levels were lower in the victims of multiple sexual assaults (p=0.03 and p=0.04, respectively). Cortisol and ACTH levels were lower in the victims of sexual abuse within the family; however, BDNF did not show a significant diffe