Diagnostic Requirements #

Essential Features: #

• Mood instability over an extended period of time (i.e., 2 years or more) characterized by numerous hypomanic and depressive periods. (In children and adolescents depressed mood can manifest as pervasive irritability.) Hypomanic periods may or may not have been sufficiently severe or prolonged to meet the diagnostic requirements for a Hypomanic Episode.
• Mood symptoms are present for more days than not. While brief symptom-free intervals are consistent with the diagnosis, there have never been any prolonged symptom-free periods (e.g., lasting 2 months or more) since the onset of the disorder.
• There is no history of Manic or Mixed Episodes.
• During the first 2 years of the disorder, there has never been a 2-week period during which the number and duration of symptoms were sufficient to meet the diagnostic requirements for a Depressive Episode.
• The symptoms are not a manifestation of another medical condition (e.g., hyperthyroidism) and are not due to the effects of a substance or medication on the central nervous system (e.g., stimulants), including withdrawal effects.
• The symptoms result in significant distress about experiencing persistent mood instability or significant impairment in personal, family, social, educational, occupational, or other important areas of functioning. If functioning is maintained, it is only through significant additional effort.

Additional Clinical Features: #

• In children, it may be appropriate to assign the diagnosis of Cyclothymic Disorder after a somewhat briefer period of initial symptoms (e.g., 1 year).
• Individuals initially diagnosed with Cyclothymic Disorder are at high risk for developing Bipolar Type I or Bipolar Type II Disorder during their lifetime.
• Individuals with Cyclothymic Disorder do not typically exhibit psychotic symptoms.

Boundary with Normality (Threshold): #

• Cyclothymic Disorder is distinguished from normal variations in mood by a history of distress or difficulty functioning due to repeated occurrences of mood disturbance.

Course Features #

• The course of Cyclothymic Disorder is often gradual and persistent. Onset of Cyclothymic Disorder commonly occurs during adolescence or early adulthood and may be difficult to differentiate from normal mood instability associated with hormonal changes that accompany puberty.

Developmental Presentations: #

• Onset of Cyclothymic Disorder in children typically occurs before the age of 10. Symptoms of irritability (particularly during periods of low mood) and sleep disturbance are often the prominent clinical features and reasons for consultation.
• Cyclothymic Disorder is underdiagnosed in children and adolescents despite evidence for greater prevalence of this disorder in this age group as compared to Bipolar Type I and Type II Disorders. However, the most common trajectory in children and adolescents is symptom remission; only a minority will maintain the diagnosis into adulthood or be at high risk for developing Bipolar Type I or Bipolar Type II Disorder.
• Co-occurrence with other Mental, Behavioural or Neurodevelopmental Disorders is common in children and adolescents with Cyclothymic Disorder, particularly with Attention Deficit Hyperactivity Disorder.

Culture-Related Features: #

• There is little information available about cultural influences on Cyclothymic Disorder. The information on Culture-Related Features for Bipolar Type I Disorder and Bipolar Type II Disorder may be relevant.

Sex- and/or Gender-Related Features: #

• There are no known differences in prevalence rates between genders for Cyclothymic Disorder.

Boundaries with Other Disorders and Conditions (Differential Diagnosis): #

• Boundary with Single Episode Depressive Disorder and Recurrent Depressive Disorder: During the first 2 years of the disorder, depressive periods in Cyclothymic Disorder should not be sufficient to meet the diagnostic requirements for a Depressive Episode. Outside of this 2-year period, there may be instances in which the symptoms are severe enough to constitute a Depressive Episode. In such cases, if there is no history of Hypomanic Episodes, Single Episode Depressive Disorder or Recurrent Depressive Disorder may be diagnosed along with Cyclothymic Disorder.
• Boundary with Bipolar Type I Disorder: If the number and severity of symptoms reaches the diagnostic threshold for a Manic Episode or a Mixed Episode in the context of an ongoing Cyclothymic Disorder, the diagnosis should be changed to Bipolar Type I Disorder.
• Boundary with Bipolar Type II Disorder: If the number and severity of symptoms reaches the diagnostic threshold for Single Episode Depressive Disorder or Recurrent Depressive Disorder in the context of an ongoing Cyclothymic Disorder and the individual has a history of Hypomanic Episodes but no history of Manic or Mixed Episodes, the diagnosis should be changed to Bipolar Type II disorder.
• Boundary with Attention Deficit Hyperactivity Disorder: Although hypomanic symptoms overlap with symptoms of Attention Deficit Hyperactivity Disorder such as distractibility, hyperactivity, and impulsivity, Hypomanic Episodes are differentiated from Attention Deficit Hyperactivity Disorder by their episodic nature and the accompanying elevated, euphoric or irritable mood. Attention Deficit Hyperactivity Disorder and Cyclothymic Disorder can co-occur and, when this occurs, Attention Deficit Hyperactivity Disorder symptoms tend to worsen during Hypomanic Episodes.
• Boundary with Oppositional Defiant Disorder: It is common, particularly among children and adolescents, for patterns of noncompliance and symptoms of irritability/anger to arise as part of a Mood Disorder. For example, noncompliance may be a result of depressive symptoms (e.g., diminished interest or pleasure in activities, difficulty concentrating, hopelessness, psychomotor retardation, reduced energy). Individuals may be less likely to follow rules and comply with directions when experiencing hypomanic symptoms. In contrast, individuals with Oppositional Defiant Disorder do not exhibit the episodicity characteristic of Cyclothymic Disorder. However, Oppositional Defiant Disorder often co-occurs with Mood Disorders, and irritability/anger can be a common symptom across these disorders. When the behaviour problems occur primarily in the context of mood disturbance, a separate diagnosis of Oppositional Defiant Disorder should not be assigned. However, both diagnoses may be given if the full diagnostic requirements for both disorders are met and the behaviour problems associated with Oppositional Defiant Disorder are observed outside of periods of mood disturbance. The Oppositional Defiant Disorder specifier ‘with chronic irritability-anger’ may be used if appropriate.
• Boundary with Personality Disorder: Individuals with Personality Disorder may exhibit impulsivity or mood instability, but Cyclothymic Disorder does not include persistent problems in self-functioning and interpersonal dysfunction that characterize Personality Disorder. Personality Disorder should be assessed outside the context of a Mood Episode to avoid conflating symptoms of a Mood Episode with personality traits, but both diagnoses may be assigned if the diagnostic requirements for both diagnoses are fulfilled.
• Boundary with Secondary Mood Syndrome: Chronic mood instability that is a manifestation of another medical condition should be diagnosed as Secondary Mood Syndrome rather than Cyclothymic Disorder.
• Boundary with Substance-induced Mood Disorder: Chronic mood instability due to the effects of a substance or medication on the central nervous system (e.g., benzodiazepines), including withdrawal effects (e.g., from stimulants), should be diagnosed as Substance-Induced Mood Disorder rather than Cyclothymic Disorder.