This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 'There are a number of biological systems that regulate the human response to stress, including the hypothalamic-pituitary-adrenal (HPA) axis which produces hormones like cortisol and catecholamines. Dysregulation in these systems is sometimes called "allostatic load" or AL. Studies have shown AL dysregulation and a smaller hippocampus (a brain structure) among individuals with chronic posttraumatic stress disorder (PTSD) and major depressive disorder (MDD). However, we do not know the exact relationship between AL system dysregulation and hippocampal size among individuals who have experienced acute and chronic stress. Also, we do not know if the relationship depends on the presence of current PTSD or MDD symptoms. Perhaps AL and structural brain changes can also be seen in stressed individuals without symptoms. This project investigates the relationship between biomarkers of stress-influenced biological systems (AL) and hippocampal size. Research participants will consist of female primary careproviders (e.g., mothers) of children who have been diagnosed with a serious illness such as cancer, epilepsy, asthma, diabetes or autism. Previous research has shown that some mothers will develop symptoms of PTSD or MDD and some will not, but all will undergo chronic stress as they cope with their child's illness and its treatment. Thus, it will be possible to study stress-system dysregulation and hippocampal size in relation to PTSD or MDD. Mothers of children with a serious illness will be assessed for a) PTSD, MDD and other related symptoms of mood disturbance; b) dysregulation in stress-influenced biological systems (AL: urinary cortisol, dopamine, norepinephrine and epinephrine; systolic and diastolic blood pressure; and waist-to-hip ratio) and c) reduced hippocampal size (via Magnetic Resonance Imaging (MRI). The study will provide much-needed data on the impact of acute and chronic stress on biological systems and brain structure and may help in the development of prevention and treatment efforts in the future.