Factor structure of the Night Eating Diagnostic Questionnaire (NEDQ) and an evaluation of the diagnostic criteria of the night eating syndrome

Background The Night Eating Diagnostic Questionnaire (NEDQ) is a validated assessment of the night eating syndrome (NES) based on the proposed diagnostic criteria. While past results show that NEDQ is associated with psychopathology and body mass index (BMI), the relationships between the proposed NES diagnostic criteria and psychopathology and BMI have not been investigated. Thus, the relationships between the proposed NES diagnostic criteria and factors previously associated with NES, namely depression, "food addiction" (FA), sleep quality, and BMI were examined. Finally, the NEDQ factor structure was examined for the first time in order to determine whether the NEDQ is assessing NES appropriately. Methods The NEDQ, depression, sleep quality, and FA questionnaires were administered to a sample of older community members (n = 468) and a student sample (n = 254). Principal Components Analysis (PCA) was performed to examine the factor structure of the NEDQ. The relationships between the proposed diagnostic criteria and depression, sleep quality, FA, and BMI were examined using multiple regression. Results The proposed NES criteria were highly intercorrelated. PCA revealed a single factor solution for the NEDQ. In the community sample, depression was associated with the presence of five of nine proposed diagnostic criteria while poor sleep quality and FA were associated with the presence of seven and six criteria respectively. In the community sample, only the sleep problems and impairment/distress criteria were positively associated with BMI. In the student sample, fewer criteria were associated with psychopathology, and no criteria were associated with BMI. Conclusions These findings support the proposed criteria for diagnosis of NES. All proposed criteria were associated with at least one psychopathology measure. BMI was only associated with the sleep problems and impairment/distress criteria in the community sample. The PCA finding of a single factor indicates that the NEDQ is a cohesive assessment of NES, and that the NEDQ is a good measure of NES criteria.