[ relationship among brain / behavioral systems, social support and depression]

ABSTRACT

Since the first theory proposed by Hippocrates about the etiology of depression, many theories have been stated and each of them have emphasized on special factors as a cause of depression. These factors might be genetic [the literature of depression in family] biological [disturbance of chemical materials in body or disturbance of neurotransmitters], psychological [lack of close relationship with individuals, deprivation from mother's love] or environmental [family experiences, negative events in recent years] and in many cases they overlap one another. Among the studies that emphasize on environmental factors, the importance of social support has been considered as a preventive factor for tendency to depression. It seems the evaluation of biological factors that are effective on depression indicates the important contribution of genetic and environmental factors to develop depression. Many studies which has been conducted on the biological determinates of depression have shown some personality characteristics that leading to depression. Among these characteristics we encounter constitutional factors. It seems, there are biological individual differences that will be more susceptible to depression. According to Gray's theory, individual differences in functioning of brain/behavioral systems and interaction between them, is the base of human mood. Gray proposed three brain/behavioral systems 1] behavioral inhibition system [BIS]; 2] behavioral activation system [BAS] and 3] fight / flight system [FFS].Gray's theory postulates that individuals that are low on the BAS dimension will be more susceptible to depression, whereas individuals that are high on the BIS dimension will be more susceptible to anxiety disorders. Fowles [2000] considered the activity of BIS with anxiety and frustration, and stated that the activity of BAS comes along with hope and relief. Therefore, it seems the sensitivity of each brain/behavioral system has different effects on different persons. In agreement with Gray's personality theory, the present study has designed to test the effect of the brain/behavioral systems in mediating the relationship between social support and depression. For this purpose, 195 females [average age 27.9] from the faculties [management, accountancy and teacher's education] of Azad University [Tehran South Branch] were selected randomly by stratified cluster sampling [based on the clusters of faculty and course]. Subjects completed three questionnaires 1] Gray-Wilson Personality Questionnaire [GWPQ]; 2] Social Support Questionnaire [Wax and et al] and 3] Beck Depressive Inventory [BDI]. Multiple regression analysis was conducted to examine the hypothesis that the interaction of the social support and behavioral inhibition system would significantly predict the severity of depression. Also, semi-partial correlation was done to determine the effects of independent and mediating variables on the variance of dependent variable. The results indicated that a] there was negative relationship[r= -0.464, p<0.01] between social support and depression; b]the behavioral activation system and depression did not relate significantly [r=0.083]; c] the relation between the behavioral inhibition system and depression was significant [r= 0.324, p<0.01] and d] in the condition of low social support, the tendency to depression was high, but the behavioral inhibition system mediated this relationship. Although there was a relationship between depression and social support, this relation will be more in the case of high sensitivity of behavioral inhibition system. On the other hand, in the condition of low social support, individuals with high sensitivity of behavioral activation system in comparison with those with high sensitivity of behavioral inhibition system, are more likely to become depressive