Differences between bipolar disorder types 1 and 2 support the DSM two-syndrome concept

Abstract

Objective To compare characteristics of bipolar disorder patients diagnosed as DSM-5 types I (BD-1) vs. II (BD-2). Methods We compared descriptive, psychopathological, and treatment characteristics in a sample of 1377 consenting, closely and repeatedly evaluated adult BD patient-subjects from a specialty clinic, using bivariate methods and logistic multivariable modeling. Results Factors found more among BD-2 > BD-1 cases included: [a] descriptors (more familial affective disorder, older at onset, diagnosis and first-treatment, more education, employment and higher socioeconomic status, more marriage and children, and less obesity); [b] morbidity (more general medical diagnoses, less drug abuse and smoking, more initial depression and less [hypo]mania or psychosis, longer episodes, higher intake depression and anxiety ratings, less mood-switching with antidepressants, less seasonal mood-change, greater %-time depressed and less [hypo]manic, fewer hospitalizations, more depression-predominant polarity, DMI > MDI course-pattern, and less violent suicidal behavior); [c] specific item-scores with initial HDRS21 (higher scores for depression, guilt, suicidality, insomnia, anxiety, agitation, gastrointestinal symptoms, hypochondriasis and weight-loss, with less psychomotor retardation, depersonalization, or paranoia); and [d] treatment (less use of lithium or antipsychotics, more antidepressant and benzodiazepine treatment). Conclusions BD-2 was characterized by more prominent and longer depressions with some hypomania and mixed-features but not mania and rarely psychosis. BD-2 subjects had higher socioeconomic and functional status but also high levels of long-term morbidity and suicidal risk. Accordingly, BD-2 is dissimilar to, but not necessarily less severe than BD-1, consistent with being distinct syndromes.

Two bipolar disorders or one? In reply to commentary by Malhi and Bell

“…Contrary to the authors’ claim, the report by Tondo et al ( 2022 ) contains abundant information supporting the descriptive differentiation of two bipolar subtypes, as well as addressing the clinical utility of doing so. Indeed, the discussion section of that report includes the following statement: We agree that a dimensional model of BD reflects more closely the variability of a complex illness, as was recognized early by Gerald Klerman, but use of a categorical model is more immediate for epidemiological and genomic studies, routine clinical use, scientific communication, and helpful for systematic classifications.…”

“…Malhi and Bell ( 2022 ) provide a critical commentary on the study by Tondo et al ( 2022 ), both published in the International Journal of Bipolar Disorders . Their title, The Bipolar Two-Syndrome Concept: Questioning the Shaping of A Circular Argument for Subtyping a Dimensional Disorder , makes clear the provocative nature of their commentary.…”

Effects of Treatment of Acute Major Depressive Episodes in Bipolar I Versus Bipolar II Disorders With Quetiapine

“…It was not possible quantitatively to compare initial depression severity in the diagnostic groups in included head-to-head trials for lack of data on initial MADRS ratings. However, several studies support the impression that the illness-course in BD2 can be more severe than in BD1, particularly regarding depressive morbidity, including a tendency to follow the less favorable "DMI" course-pattern (depression before mania, followed by a euthymic interval), [43][44][45][46] although initial MADRS ratings of depression under comparable conditions can be somewhat higher among BD1 than BD2 patients. 46 Quetiapine has been recommended as a first-line treatment for bipolar depression.…”

The bipolar two-syndrome concept: questioning the shaping of a circular argument for subtyping a dimensional disorder

“…The study (Tondo et.al. 2022 ) examined 1377 patients attending a specialist mood disorders clinic. They were diagnosed as having either bipolar I or bipolar II disorder, based on DSM-5 criteria.…”

“…In a recent paper published in this journal by Tondo and colleagues (Tondo et.al. 2022 ), the authors set out to compare the characteristics of bipolar disorder patients diagnosed as bipolar I and II according to DSM-5. The paper examines more than 1300 subjects and predictably identifies differences of severity across a range of parameters.…”