| A heated controversy exists about whether clinical depression is marked by a distinct collection of symptoms that represent a qualitatively discrete diagnostic category or whether mild, moderate, and severe states of the disorder are best conceptualized as existing along a continuum. Although most research generally corroborates a continuous conceptualization of depression (Flett, Vrendenburg, & Krames, 1997), these studies have relied predominantly on surface-level (manifest) characteristics of the disorder to infer something about the fundamental structure of depression (Ruscio & Ruscio, 2000). The problem with this approach is that underlying (latent) groups can appear continuous at the manifest level. Many suggest that such shortcomings can and should be reconciled by a family of statistical procedures that are designed specifically for the purpose of distinguishing types from continua at the latent level of analysis (Ruscio & Ruscio, 2000). This set of procedures is called the taxometric method.;The present study used three taxometric procedures, Mean Above Minus Below A Cut (MAMBAC; Meehl & Yonce, 1994), MAXimum EIGenvalue (MAXEIG; Waller & Meehl, 1998), and Latent Mode (L-Made; Waller & Meehl, 1998) to evaluate the latent structure of two aspects of depression, major depression as conceptualized in the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1996), and involuntary defeat syndrome (Gilbert, 1992, 2000). Analyses were performed on data obtained from 7711 mixed-sex participants who participated in the National Comorbidity Survey (NCS; Kessler, 2000). The preponderance of evidence derived from these analyses tends to suggest that a latent dimensional solution best represents both aspects of depression, however, the results were not unequivocal.;The current study adds to the existing literature on depression in several important ways. First, the use of the NCS sample broadens existing conclusions about the latent structure of depression. To date, no other taxometric analysis has investigated the latent structure of depression in a large epidemiologically based adult sample. Second, the results of this analysis support the contention that major depression is more aptly conceptualized as a continuous construct. Finally, the results of this analysis have important implications for how important correlates of depression are researched and treated.;Key Words. Taxometric, Major depression, Involuntary defeat syndrome, DSM-IV, NCS. |
