BACKGROUND: The introduction of screening questionnaires, such as the Mood Disorder Questionnaire (MDQ), has stimulated clinical and epidemiological studies on bipolar disorders. In this work, we studied the item response pattern of the MDQ in the Italian population and compared the results with those of the validation of the MDQ in Asian studies (Chinese and Korean), analyzing similarities and differences among the populations studied. METHODS: The sample was made up of 2278 participants, distributed as follows: 56.6% females, 50.8% living in the north-central Italy, and 33.7% living in rural areas. The factor analysis was run on the matrix of tetrachoric correlations. The psychometric properties of the MDQ were also studied using the Rasch logistic model. RESULTS: The parallel analysis found two significant components. The first includes symptoms referring to acceleration, danger and irritability as risky behaviors, social interaction problems and mental flow. The second includes symptoms referring to self-confidence and energy. With respect to the Korean/Chinese results, the Italian sample, item 11 ("much more sex"), appears related to self-confidence and energy, while in Asia it is connected with items expressing risky behaviors and irritability. LIMITATIONS: Differences in the frequency of comorbid disorders in Asian and Italian populations should be considered. The results should be confirmed and compared with those of other populations. CONCLUSIONS: Cultural differences appear to be associated with a different symptomatic expression of bipolar spectrum disorders. Future research will investigate the role of gene-environment interaction in the genesis of these differences.
BACKGROUND: The introduction of screening questionnaires, such as the Mood Disorder Questionnaire (MDQ), has stimulated clinical and epidemiological studies on bipolar disorders. In this work, we studied the item response pattern of the MDQ in the Italian population and compared the results with those of the validation of the MDQ in Asian studies (Chinese and Korean), analyzing similarities and differences among the populations studied. METHODS: The sample was made up of 2278 participants, distributed as follows: 56.6% females, 50.8% living in the north-central Italy, and 33.7% living in rural areas. The factor analysis was run on the matrix of tetrachoric correlations. The psychometric properties of the MDQ were also studied using the Rasch logistic model. RESULTS: The parallel analysis found two significant components. The first includes symptoms referring to acceleration, danger and irritability as risky behaviors, social interaction problems and mental flow. The second includes symptoms referring to self-confidence and energy. With respect to the Korean/Chinese results, the Italian sample, item 11 ("much more sex"), appears related to self-confidence and energy, while in Asia it is connected with items expressing risky behaviors and irritability. LIMITATIONS: Differences in the frequency of comorbid disorders in Asian and Italian populations should be considered. The results should be confirmed and compared with those of other populations. CONCLUSIONS: Cultural differences appear to be associated with a different symptomatic expression of bipolar spectrum disorders. Future research will investigate the role of gene-environment interaction in the genesis of these differences.