Toward a Developmental Nosology for Disruptive Mood Dysregulation Disorder in Early Childhood.

Objective: Disruptive mood dysregulation disorder (DMDD) in DSM, characterized by severe, chronic irritability, currently excludes children <6 years of age. However, capitalizing on a burgeoning developmental science base to differentiate clinically salient irritability in young children may enable earlier identification. The objective of this study was to advance an empirically derived framework for early childhood DMDD (EC-DMDD) by modeling and validating DMDD patterns in early childhood and generating clinically informative, optimized behaviors with thresholds.

Method: Data (N = 425) were from 3 longitudinal assessments of the MAPS Study, spanning preschool (means = 4.7 and 5.5 years) to early school age (mean = 6.8 years). The Multidimensional Assessment Profile of Disruptive Behavior (MAP-DB) Temper Loss scale captured irritability, the Family Life Impairment Scale (FLIS) assessed cross-domain impairment at the preschool time points and the Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS) was used to assess clinical status at early school age. Latent transition analyses differentiated children with EC-DMDD from children with low, transient, or nonimpairing irritability.

Results: Developmental patterning of irritability proved important for normal:abnormal differentiation. Of children, 27% had initially high irritability, but only two-thirds of these were persistently highly irritable. Thus, "false positives" based on a single screen would be substantial. Yet, "false negatives" are low, as <1% of children with baseline low irritability demonstrated later high irritability. Based on the sequential preschool-age time points, 6.7% of children were identified with EC-DMDD, characterized by persistent irritability with pervasive impairment, similar to prevalence at older ages. Specific behaviors included low frustration tolerance; dysregulated, developmentally unexpectable tantrums; and sustained irritable mood, all of which sensitively (0.85-0.96) and specifically (0.80-0.91) identified EC-DMDD. EC-DMDD predicted irritability-related syndromes (DMDD, oppositional defiant disorder) at early school age better than downward extension of DSM DMDD criteria to preschool age.

Conclusion: These findings provide empirical thresholds for preschool-age clinical identification of DMDD patterns. The results lay the foundation for validation of DMDD in early childhood and inform revision of DSM criteria.