Major Depressive Disorder With Subthreshold Bipolarity: Exploring and Managing New Diagnoses

An emphasis on treatment equal to the emphasis on pathology, genetics, or course of illness may cordon off potential new disorders from clinical application until their clinical utility can be assessed. Since treatments for many differing disorders involve the same or similar modalities (e.g., cognitive-behavioral therapy, antidepressants), this approach may facilitate linkages among disorders (3). As an example, substance abuse and dependence could telescope down to a single substance use disorder because treatment and prognoses fail to distinguish the two subgroups despite their differences along genetic, pathological, and other characteristics.

The focus on “spectrum disorders” may reduce the number of overarching categories despite the fact that some subcategories are multiplying. For example, mood disorders may range from bipolar I through dysthymia through adjustment reaction with mood symptoms. Schizophrenia spectrum, impulsive behavioral spectrum, certain neurotransmitter spectra, and other spectra are being discussed. This approach may help clinicians master the complexity of new findings while providing an understandable paradigm to the general population. It might persuade the population, our social institutions, and our profession of the importance of discerning ways to contain any given “spectrum disorder” at its least disabling and least morbid stage.

A growing emphasis on “longitudinal comorbidity” is also informing us about what disorders are apt to ensue in the wake of an earlier disorder. This provides us with additional opportunities to prevent the subsequent disorders and to learn the progenitors of disorders (since the parties to these sequences often follow a patterned rather than a random progression). An example is the subsequent development of mood disorder in those who have had an anxiety disorder (4)-an example of internalizing disorders recurring over time in altered form. Primary care clinicians as well as mental health professionals need lucid models to understand longitudinal comorbidity in order to skillfully monitor patients over time and implement prompt interventions as needed (5).

The resurrection of internalizing-versus-externalizing psychiatric disorder, after almost a half century of relative neglect, may bring some order to the field. Although these moieties were originally employed for the study of children, research in adults has shown nonrandom co-occurrence of internalizing disorders with one another and of externalizing disorders with one another. Grouping mood and anxiety disorders into a single internalizing category has advanced the search for causation, exemplified by the combining of adverse childhood events with internalizing disorder to produce substance use disorder (6). Likewise, grouping externalizing disorders has increased our knowledge, as shown by the interaction of genetic and environmental factors to produce diverse externalizing disorders (7).

As clinicians come to better understand diagnoses, they will be able to educate patients and families more successfully than in the past. This will serve the large number of suffering people whose need for care goes unmet (8). Although treatment seeking by now-untreated legions of people could overwhelm resources (9), the development of computer-based or computer-augmented therapy may increase treatment success while reducing cost (10).