Characterizing major depression phenotypes by presence and type of psychomotor disturbance in adolescents and young adults.

Major depressive disorder (MDD) is phenomenologically heterogeneous, which has prompted investigation of intermediate MDD phenotypes based on specific key symptoms. Presence and type of psychomotor disturbance may be an important psychopathologic feature that differentiates clinically distinct forms of juvenile MDD. This study examined the phenotypic status of three putative MDD phenotypes in a community sample of 941 youths: (1) agitated depression (MDD with psychomotor agitation), (2) retarded depression (MDD with psychomotor retardation), and (3) agitated-retarded depression (MDD with psychomotor agitation and retardation within an episode). Hasler et al.'s [2004: Neuropsychopharmacology 29:1765-1781] criteria of specificity (degree of association with relevant symptoms and conditions related to the disease of interest versus other psychiatric conditions), stability (degree of stability over time), and heritability (degree of familial aggregation with relevant conditions) were used to evaluate the phenotypic significance of these subtypes. Results were suggestive that agitated depression was a relatively specific phenotypic syndrome characterized by irritability, arousal, physical complaints, and vulnerability to anxiety disorders and alcohol dependence; low stability across depressive episodes; and low heritability. Agitated-retarded depression was relatively specific and characterized by increased severity, recurrence, vegetative symptoms, suicidal ideation, social impairment, endogeneity, and vulnerability to anxiety disorders and bulimia; low stability across episodes; and modest heritability. Although retarded depression was associated with some specific distinguishing characteristics, most associations were explained by the increased severity of this phenotype. Retarded depression evidenced little stability or heritability. These findings offer partial support of the phenotypic status of agitated and agitated-retarded depression in youths.