Transitioning from Bipolar II to Bipolar I Disorder in Late Life: Implications for Practice

Sir,

The issue of diagnostic validity of Bipolar Disorder (BD)-II continues to divide expert opinion. While some argue for a separate diagnostic status for BD-II based on true genetic breeding, others point out the significant minority who eventually convert to more disabling BD-I to argue against giving BD-II a separate diagnostic status.[12] Early age of onset has been one of the most consistently replicated risk factors for progression from BD-II to BD-I.[3] We report the case of an elderly lady who converted from a baseline diagnosis of BD-II to BD-I after two decades of illness.

A 60-year-old lady presented to outpatient psychiatry services with the 2-week history of pervasive irritability, increased psychomotor activity, increased self-esteem, pressured speech, and decreased need for sleep. A file review revealed two initial depressive episodes followed by multiple hypomanic episodes occurring at an interval of 2 years, each lasting for an average of 15 days duration. After the first depressive episode, she was initiated on capsule fluoxetine 40 mg which was continued for next 3 years. Later, in 2011, for her second depressive episode, she was stabilized on tablet amitriptyline 100 mg which she was continuing till the index presentation. Based on this information, until the current episode, a lifetime diagnosis of BD-II looked appropriate.

Due to the extreme degree of excitement and aggression, the patient was offered inpatient care. Baseline blood biochemistry, metabolic panel, and imaging study were unremarkable. We made a diagnosis of BD-I – Current Episode Mania with Psychotic symptoms and started her on tablet lithium 600 mg and tablet chlorpromazine 200 mg after stopping amitriptyline. Over the next 2 weeks, she experienced significant improvement with this regimen. The patient was discharged and is maintaining well for the last 3 months.

The present case describes a patient who eventually converted from BD-II to BD-I after two decades of illness onset. Birmaher et al., in two separate longitudinal studies on childhood-onset BD-II (mean follow-up for 2–4 years), have reported nearly 20%–25% progression to more severe bipolar-I.[45] In a 10-year follow-up study on adults, the authors found a 5%–7% conversion rate of BD-II to BD-I.[6] There are a couple of clinical implications from the index case: first that soft bipolar subtypes with their onset in the fifth decade of life may also eventually convert to BD-I, and second, this conversion may happen even after two decades of illness onset. Some authors have elaborated on the role of behavioral approach system (BAS) which represents a behavioral-motivation system that regulates approach to a range of rewards and safety cues. Individuals with BD, in this model, are believed to be hypersensitive to reward relevant cues, and this has been confirmed in many self-report and behavioral task-based studies.[7] However, it remains to be established whether the BAS sensitivity theory may identify individuals likely to convert to more severe bipolar variants with time. We hope this report spurs further research on the construct validity of a diagnosis of BD-II.