Mental Health Inventory for Infants: Scale Development and Japanese Infants' Characteristics

Early detection and treatment promote positive outcomes in mental health problems among infants. This study developed a simple and reliable screening inventory for infants' mental health. Participants were 579 primary caregivers who had Japanese infants aged 2-6 years. Participants evaluated their children using the Mental Health Inventory for Infants (MHII; developed in this study), which contains 24 items. Exploratory factorial analysis identified the MHII factor structure; confirmatory factorial analysis examined its factorial validity. Internal consistency and criterion-related validity were also examined. Irritability (8 items), somatic symptoms (6 items), and signs of insecurity (4 items) were identified as factors in the MHII; each of these factors measures a critical aspect of infants' mental health. The MHII's internal consistency and scale homogeneity were acceptable; its criterion-related validity was supported. In this study, male infants exhibited greater irritability and less insecurity than females. The present results support the MHII's reliability and validity; additionally, they indicate that caregivers may use the MHII to quickly screen for three critical aspects of infants' mental health. We expect that the MHII will be used for early detection of mental health difficulties in infants to facilitate treatment.