Motivational predictors of weight loss and weight-loss maintenance.

Self-determination theory proposes that behavior change will occur and persist if it is autonomously motivated. Autonomous motivation for a behavior is theorized to be a function both of individual differences in the autonomy orientation from the General Causality Orientations Scale and of the degree of autonomy supportiveness of relevant social contexts. We tested the theory with 128 patients in a 6-month, very-low-calorie weight-loss program with a 23-month follow-up. Analyses confirmed the predictions that (a) participants whose motivation for weight loss was more autonomous would attend the program more regularly, lose more weight during the program, and evidence greater maintained weight loss at follow-up, and (b) participants' autonomous motivation for weight loss would be predicted both by their autonomy orientation and by the perceived autonomy supportiveness of the interpersonal climate created by the health-care staff.

Clinical diagnosis of multiple sclerosis. The impact of magnetic resonance imaging and ancillary testing. Rochester-Toronto Magnetic Resonance Study Group.

OBJECTIVE: Magnetic resonance imaging, computed tomography, cerebrospinal fluid analysis, and evoked potential testing are used to assist in the diagnosis of patients suspected to have multiple sclerosis (MS). The impact of these tests on a clinician's diagnosis of patients suspected to have MS has not been studied systematically. DESIGN: Clinicians made a diagnosis of each patient following clinical evaluation, again after reviewing the results of magnetic resonance imaging, and finally after reviewing information from other laboratory testing. These diagnoses were compared with the criterion standard of a masked "gold standard" panel reviewing all information after a mean follow-up of 0.9 year. SETTING: The General Neurology Clinic and Multiple Sclerosis Clinic of the University of Rochester (NY). PATIENTS: A consecutive sample of 62 patients diagnosed as having either possible or probable MS following clinical evaluation. MAIN OUTCOME MEASURE: Changes in diagnostic certainty of clinicians following incremental presentation of new laboratory data and the accuracy of such diagnoses. RESULTS: Clinicians used magnetic resonance imaging findings to diagnose definite MS or to eliminate MS from diagnostic consideration in 44% of cases. In these cases, further laboratory testing did not alter clinicians' decisions. In the remaining 56% of cases, in which magnetic resonance imaging did not lead to a diagnosis of definite MS or eliminate MS from diagnostic consideration, further laboratory testing led to such diagnoses in an additional 13% of cases. Gold standard diagnoses were in agreement with the clinician's assessments. CONCLUSIONS: Magnetic resonance imaging aids in the evaluation of patients suspected to have MS; other subsequent studies (computed tomography, cerebrospinal fluid analysis, and evoked potential testing) have less impact. After all studies are performed, about half of such patients still have a tentative diagnosis.