| dc.description | The currently used diagnostic system for psychiatric disorders is not based on etiology or pathophysiology, as these aspects of such illnesses are still poorly understood. Similarly, it remains very difficult to predict, with any accuracy, illness course or treatment response. This thesis aimed to investigate potential biomarkers for the course and response to treatment of several pediatric psychiatric illnesses. The pituitary gland was chosen as a viable candidate for such a biomarker, as it is a very plastic organ, responsive to changes in physiological function, and amenable for morphological study using in vivo imaging techniques such as magnetic resonance imaging (MRI). Childhood and adolescence are active periods of growth, and are often the time of onset for many major psychiatric illnesses. Moreover, sex differences in illness onset and prevalence are common during this period, and the pituitary gland displays marked sex-related morphological differences during this period of growth. Functionally, the pituitary gland plays a central role in the stress response, which is strongly implicated in both mood and anxiety disorders. The core hypothesis of this thesis is that childhood and adolescent psychiatric diseases involving the function of the pituitary gland will exhibit abnormal pituitary morphology that is detectable with MRI. Data on pituitary gland volumes were collected from patients with anxiety disorders (obsessive compulsive disorder or OCD), mood disorders (major depressive disorder or MDD and bipolar disorder) and behavioral disorders (attention deficit hyperactivity disorder or ADHD) as well as healthy control subjects. In mood disorders, the pituitary gland was found to be larger than those of healthy controls, while in anxiety disorders it was found to be smaller than healthy controls'. In behavioral disorders, no difference was noted in pituitary gland size. Pharmacological treatment, while effective at reducing symptoms, did not affect pituitary volume in any of these populations. In conclusion, pituitary gland volume appears to be differentially affected in these illnesses, but not relatable to the reduction of symptoms, per se, or to the effects of psychotherapeutic medication. Future studies of the pituitary gland in mental illness, conducted in concert with direct measures of endocrine function, will shed further light on the role of the gland in psychiatric disease. | en_US |
