Severe, recurrent temper outbursts were present in 52% of the LAMS sample, and chronic irritability was present in 35%. The DMDD phenotype was present in 26% (n = 184) of LAMS participants and was significantly more common in the ESM+ vs ESM– participants (28% vs 14%; relative risk [RR] = 1.99; 95% confidence interval [CI], 1.16–3.41; P = .006), so ESM status was included as a potential covariate in the multivariate models. An additional 5% (n = 34) of the sample had both severe, recurrent temper outbursts and chronic irritability, but did not meet full criteria for DMDD because they did not have impairment in 2 settings (n = 27), did not meet duration criteria (n = 3), or met neither the impairment nor duration criteria (n = 4).
compares the 184 DMDD+ participants with the 522 DMDD– participants on factors measured at intake. DMDD+ participants did not significantly differ from DMDD– participants in the rates of bipolar spectrum diagnoses, any depressive disorders, MDD, or anxiety disorders. DMDD+ participants had higher rates of disruptive behavior disorders, dysthymia, elimination disorders, and ADHD as compared to the DMDD– group. In the multivariate model, only oppositional defiant disorder and conduct disorder remained significantly associated with DMDD (oppositional defiant disorder: Wald χ2 = 124, odds ratio [OR] = 68.7 [95% CI, 32.6–144.7], P < .0001; conduct disorder: Wald χ2 = 92, OR = 77.8 [95% CI, 32.0–189.1], P < .0001).
Factors at Intake by Disruptive Mood Dysregulation Disorder Status
On dimensional measures of psychopathology, DMDD+ youth had significantly higher total scores on the Young Mania Rating Scale, CDRS-R, and K-SADS Mania Rating Scale (all with the irritability item removed), the K-SADS Depression Rating Scale, and the CAASI-4R ADHD subscales and oppositional defiant disorder and conduct disorder scales. On multivariate analysis, only the CAASI-4R oppositional defiant disorder and conduct disorder total scores were significantly associated with DMDD (CAASI-4R oppositional defiant disorder: Wald χ2 = 45, OR = 1.16 [95% CI, 1.11–1.21], P < .0001; CAASI-4R conduct disorder: Wald χ2 = 6.1, OR = 1.05 [95% CI, 1.01–1.10], P = .01), along with nonwhite race becoming significantly associated with DMDD in the model (Wald χ2 = 5.2, OR = 1.58 [95% CI, 1.07–2.35], P = .02).
Youth with DMDD were more impaired than those without DMDD. However, they were not more likely to have repeated a grade, received special educational intervention, taken psychotropic medication, or have a history of inpatient psychiatric hospitalization.
Participants who did not complete any follow-up assessments were less likely to live with both biological parents than those who did complete a follow-up assessment (20% vs 35%); otherwise, there were no significant demographic differences between groups. There were no differences among participants without follow-up versus those with follow-up in the rates of baseline depressive disorders, bipolar spectrum diagnoses, ADHD, anxiety disorders, psychotic disorders, or oppositional defiant disorder/conduct disorder or in baseline DMDD and ESM status.
The 12-month assessment was available for 525 participants (74% of the sample), with 21% meeting DMDD criteria. Of those meeting criteria for DMDD at intake, 53% continued to meet criteria at 12 months. Of the 111 participants who were DMDD+ at the 12-month assessment, 71 (64%) were DMDD+ at intake. For comparison, 85% of participants who met full criteria for ADHD at intake also did so at the 12-month follow-up.
Both 12-month and 24-month follow-up assessments were available in 433 participants (61% of the sample). Of those 433 participants, 172 (40%) met DMDD criteria for at least 1 assessment, including 27% of the ESM– subjects. Of those 172 participants who were DMDD+ at intake or follow-up, 90 (52%) met criteria at only 1 assessment, while 50 (29%) met criteria at 2 assessments and 32 (19%) met criteria for all 3 assessments. In comparison, of the participants who met criteria for ADHD at intake or follow-up, 18% met criteria at only 1 assessment; 21%, at 2 assessments; and 61%, at all 3 assessments.
In participants with both follow-up visits, DMDD at intake was not associated with new onset of bipolar spectrum diagnoses (including bipolar I and II disorders), depressive disorders (including MDD), anxiety disorders, psychotic disorders, or conduct disorder over follow-up (). A diagnosis of DMDD at either intake or follow-up was significantly associated with a diagnosis at intake or follow-up of oppositional defiant disorder/conduct disorder (71% of those with oppositional defiant disorder/conduct disorder had DMDD vs 3% without oppositional defiant disorder/conduct disorder; χ2 = 277, P < .0001) and ADHD (44% vs 23%; χ2 = 20.0, P < .0001), but not MDD (42% vs 38%, χ2 = 0.4, P = .52), any depressive disorder (44% vs 37%, χ2 = 2.0, P = .16), bipolar I and II disorders (41% vs 38%; χ2 = 0.4, P = .52), bipolar spectrum diagnoses (44% vs 36%; χ2 = 3.1, P = .08), any anxiety disorder (41% vs 38%; χ2 = 0.4, P = .52), or psychotic disorder (52% vs 38%; χ2 = 1.9, P = .17).
New Onset of Disorder at 12- or 24-Month Follow-Up by Disruptive Mood Dysregulation Disorder Status at Intake, %
Distinction From Oppositional Defiant Disorder and Conduct Disorder
At the intake assessment, 58% of youth with oppositional defiant disorder and 61% of youth with conduct disorder were DMDD+. Nearly all (96%) of DMDD+ youth met criteria for oppositional defiant disorder or conduct disorder (RR vs DMDD– = 4.03 [95% CI, 3.44–4.70]), and 77% met criteria for both ADHD and oppositional defiant disorder/conduct disorder (RR vs DMDD– = 4.30 [95% CI, 3.52–5.26]; ). In contrast, 41% of participants with MDD (RR vs no MDD = 0.96 [95% CI, 0.68–1.36]) and 40% of those with bipolar spectrum diagnoses (RR vs no bipolar spectrum diagnoses = 0.91 [95% CI, 0.74–1.13]) had comorbid oppositional defiant disorder or conduct disorder; 27% of MDD (RR vs no MDD = 0.79 [95% CI, 0.49–1.27]) and 34% of participants with bipolar spectrum diagnoses (RR vs no bipolar spectrum diagnoses = 1.03 [95% CI, 0.74–1.13]) had both ADHD and oppositional defiant disorder/conduct disorder. There was no difference in the rate of DMDD in participants with oppositional defiant disorder/conduct disorder who were ESM+ (59%) versus those that were ESM– (55%; RR = 1.07 [95% CI, 0.71–1.61]). Participants with oppositional defiant disorder/conduct disorder who were DMDD+ did not have significantly different rates of bipolar spectrum diagnoses, depressive disorders, anxiety disorders, or ADHD compared to those who were DMDD– (). DMDD+ vs DMDD– oppositional defiant disorder/conduct disorder participants did not differ in Young Mania Rating Scale, CDRS-R, K-SADS Depression Rating Scale and K-SADS Mania Rating Scale total scores, CAASI-4R ADHD subscales, SCARED-P total scores, and Children's Global Assessment Scale.
Overlap of Disruptive Mood Dysregulation Disorder (DMDD), Attention-Deficit/Hyperactivity Disorder (ADHD), and Oppositional Defiant Disorder (ODD)/Conduct Disorder (CD)
Factors at Intake by Disruptive Mood Dysregulation Disorder Status in Participants With Oppositional Defiant Disorder or Conduct Disorder
In the participants diagnosed with oppositional defiant disorder or conduct disorder (n = 180) at intake who also had both follow-up assessments, those with DMDD did not differ significantly from those without DMDD in the rates of new onset of bipolar spectrum diagnoses (9% vs 18%; RR = 0.5 [95% CI, 0.21–1.22]), depressive disorders (12% vs 12%; RR = 0.96 [95% CI, 0.39–2.39]), psychotic disorders (3% vs 4%; RR = 0.75 [95% CI, 0.16–3.61]), or anxiety disorders (13% vs 16%; RR = 0.86 [95% CI, 0.39–1.89]).
Parental Psychiatric History
DMDD+ participants at intake did not significantly differ from DMDD– participants in the rates of a screening diagnosis in at least 1 biological parent of depression (DMDD+ 67% vs DMDD– 63%, RR = 1.06 [95% CI, 0.94–1.20]), bipolar disorder (23% vs 20%, RR = 1.19 [95% CI, 0.86–1.66]), anxiety disorder (49% vs 55%, RR = 0.88 [95% CI, 0.74–1.05]), psychotic disorder (14% vs 11%, RR = 1.31 [95% CI, 0.84–2.05]), substance use disorder (48% vs 45%, RR = 1.06 [95% CI, 0.88–1.26]), ADHD (30% vs 26%, RR = 1.12 [95% CI, 0.86–1.47]), or conduct disorder (43% vs 39%, RR = 1.10 [95% CI, 0.90–1.34]).