Stress and the susceptible brain : Neurobiological insights into the stress response in bipolar patients and siblings of schizophrenia patients

Abstract

The studies described in this thesis provide new insights into the time-dependent neurobiological consequences of acute stress in healthy controls, patients with a bipolar disorder, and siblings of schizophrenia patients. Previous research has shown that stress exerts time-dependent effects on the healthy brain. More specifically, acute stress releases noradrenaline which causes a state of hypervigilance, while the aftermath of stress is characterized by an increase of the stress hormone cortisol which plays an important role in the recovery from stress. These neural changes are hypothesized to become maladaptive in vulnerable individuals, leading to the development of psychopathology. However, studies investigating the dynamic effects of stress on the brain of at-risk individuals or patients are relatively scarce. In this thesis, I have combined functional MRI with psychosocial stress in two independent studies. Our findings indicate that neurobiological properties of stress reactivity are time-dependently affected in bipolar patients and siblings of schizophrenia patients. For example, healthy controls showed an upregulation of the brain’s reward circuitry in the aftermath of stress, which was absent in the siblings of schizophrenia patients or patients with a bipolar disorder. A lack of increase in the reward circuitry following stress may be involved in the development of psychiatric complaints. A stronger focus on how individuals recover from stress can provide an important stepping stone in changing the way people deal with stress, so that stress management can ultimately be within the reach of everyone