What are the changes in diagnosis of unspecified bipolar and related disorder across Diagnostic and Statistical Manual of Mental Disorders (DSM) 3, 4, 5, and 5-Text Revision (TR), and International Classification of Diseases (ICD) 10 and 11?

Evolution of Unspecified Bipolar and Related Disorder Diagnosis Across DSM and ICD Versions

The category of "unspecified" bipolar disorder has evolved from being a poorly defined "NOS" (not otherwise specified) category in DSM-III and DSM-IV to more structured "Other Specified" and "Unspecified" categories in DSM-5/DSM-5-TR, while ICD-11 has moved toward dimensional symptom assessment rather than relying heavily on residual categories. 1, 2

DSM-III and DSM-IV Era

• DSM-III and DSM-IV utilized "Bipolar Disorder NOS" as a catch-all category for presentations that did not meet full criteria for Bipolar I or II disorder, which resulted in a large proportion of treated patients being allocated to this vague diagnostic group 2
• This approach led to significant underdiagnosis of bipolar disorders and lacked operational definitions for subthreshold presentations 2

DSM-5 and DSM-5-TR Changes

• DSM-5 introduced operationally defined subthreshold groups and split the former NOS category into "Other Specified Bipolar and Related Disorder" (when the clinician specifies the reason) and "Unspecified Bipolar and Related Disorder" (when the clinician chooses not to specify) 2
• DSM-5 added the critical requirement that both hypomania and mania must include increased activity/energy in addition to mood elevation or irritability as entry criterion A, which paradoxically shifted some patients who previously met DSM-IV criteria for Bipolar I or II into subdiagnostic categories 2, 3
• DSM-5-TR maintained these categorical distinctions while emphasizing dimensional severity assessment, though it remains fundamentally categorical at its core without biological validation 1

ICD-10 Approach

• ICD-10 maintained a purely categorical approach to bipolar disorders without dimensional expansions, similar to earlier DSM versions 1
• ICD-10 lacked the specificity needed to capture subthreshold presentations effectively 4

ICD-11 Fundamental Restructuring

• ICD-11 fundamentally restructured the entire mental disorders chapter, grouping bipolar disorders with dimensional symptom specifiers across six domains: positive symptoms, negative symptoms, depressive symptoms, manic symptoms, psychomotor symptoms, and cognitive symptoms 1, 5
• ICD-11 requires increased activity or energy in addition to mood elevation or irritability for diagnosing hypomania, harmonizing with DSM-5 1, 6, 3
• ICD-11 emphasizes rating symptom severity on a 4-point scale ranging from "not present" to "present and severe" for each domain, reducing reliance on unspecified categories 1
• ICD-11 added dimensional qualifiers for depressive episodes including melancholic features, anxiety symptoms, panic attacks, and seasonal pattern 1

Key Harmonization Points Between DSM-5/5-TR and ICD-11

• Both systems now require the additional criterion of increased activity/energy for hypomania and mania diagnosis 1, 3
• Both recognize Bipolar II disorder as a distinct diagnostic category (ICD-11 newly added this) 6, 3
• Both have moved toward incorporating dimensional parameters to assess symptoms alongside categorical diagnoses 3, 7

Clinical Implications for Unspecified Diagnoses

• Clinicians should use structured diagnostic interviews rather than unstructured clinical assessment to reduce diagnostic bias when evaluating subthreshold presentations that might fall into unspecified categories 1
• Creating detailed life charts documenting longitudinal symptom patterns is essential, as the "Other Specified" or "Unspecified" diagnosis frequently evolves over time and may require reclassification 1
• Documenting dimensional symptom severity across multiple domains at each assessment using the ICD-11 framework provides flexibility for treatment planning even when categorical criteria are not fully met 1

Limitations of Current Systems

• Both DSM-5-TR and ICD-11 remain fundamentally categorical at their core, classifying based on observable symptoms rather than underlying pathophysiology 1
• Neither system has biological validation, resulting in biologically heterogeneous groups within the same diagnostic category 1, 5
• ICD-11 field studies showed promising but modest improvements in diagnostic accuracy compared to ICD-10, with 82.5% to 83.9% of clinicians rating ICD-11 as quite or extremely easy to use 6, 5

Common Pitfalls to Avoid

• The stricter DSM-5/ICD-11 requirement for increased activity/energy may inadvertently push some genuine bipolar presentations into unspecified categories—maintain high clinical suspicion for bipolar disorder even when this single criterion is ambiguous 2
• Avoid premature closure with an "unspecified" diagnosis; plan for longitudinal reassessment as the clinical picture often clarifies over time 1
• Do not rely solely on categorical thresholds; use dimensional assessment to capture subsyndromal symptoms that inform treatment decisions regardless of whether full diagnostic criteria are met 1, 4