Cyclothymic Disorder

Cyclothymic disorder is chronic fluctuating mood with numerous hypomanic and depressive symptoms not meeting full episode criteria, for at least 2 years (1 year in children).

• Prevalence 0.4 to 1%, onset in adolescence, equal in both sexes; often a bipolar spectrum disorder (15 to 50% progress to bipolar I or II).
• Comorbid substance misuse, anxiety, ADHD, borderline personality traits.
• Highly impairing in relationships and work; suicide risk.

• Alternating periods of elevated mood, reduced sleep, increased energy and sociability, and low mood with fatigue, with symptom free intervals under 2 months.
• Irritability, impulsivity, unstable relationships and work.
• Family history of bipolar disorder.

• DSM-5 criteria with longitudinal mood charting (daily mood diary).
• Exclude bipolar I/II (full hypomanic or depressive episodes), borderline personality disorder, ADHD, substance induced, thyroid disease.
• Mood Disorder Questionnaire, TSH, toxicology, drug review.
• Assess suicide risk.

• Psychoeducation, regular routines, social rhythm therapy, CBT, sleep regulation, family therapy.
• Mood stabilisers: lamotrigine 100 to 200 mg daily (titrate slowly over 6 weeks), lithium 600 to 1200 mg (level 0.6 to 0.8 mmol/L), valproate 500 to 1500 mg (avoid in women who may conceive), quetiapine 100 to 300 mg.
• Avoid antidepressant monotherapy (risk of mood switching and rapid cycling).
• Treat substance misuse; manage comorbid anxiety.
• Monitor for conversion to bipolar disorder.