SPECT and PET in Eating Disorders

Medical imaging techniques like PET and SPECT have been applied for investigation of brain function in anorexia and bulimia nervosa. Regional abnormalities have been detected in cerebral blood flow, glucose metabolism, the availability of several neurotransmitter receptors (serotonin 1A and 2A, dopamine D2/D3, histamine H1, mu-opioid, GABA(A)-benzodiazepine, and cannabinoid CB1), stimulant-induced dopamine release, presynaptic FDOPA influx, and the density of serotonin transporters. Different subtypes of eating disorders appear to be associated with specific functional changes. It is hard to judge whether such changes are a consequence of chronic dietary restrictions or are caused by a putative anorexia (or bulimia) nervosa endophenotype. Many abnormalities (particularly those of glucose metabolism) appear to be reversible after restoration of weight or normal patterns of food intake and may represent consequences of purging or starvation. However, some changes of regional flow and neurotransmitter systems persist even after successful therapy which suggests that these reflect traits that are independent of the state of the illness. Changes of the serotonergic system (altered activity of 5-HT1A and 5-HT2A receptors and 5-HT transporters) may contribute to dysregulation of appetite, mood, and impulse control in eating disorders and may represent a trait which predisposes to the development of anxiety, obsessionality, and behavioral inhibition. Assessment of functional changes in the brain with PET or SPECT may have prognostic value and predict neuropsychological status after several years of therapy.