Introduction

We first raise two questions. Are mood stabilisers underused in the treatment of patients with Bipolar II Disorder (BP II)? Secondly, and perhaps more centrally, do all BP II patients need to be treated with mood stabilisers?

While mood stabilisers are integral to the evidence-based management of Bipolar I Disorder (BP I), there are no large, well-designed, controlled trials specifically tailored to help guide treatment decisions about mood stabilisers for BP II patients – and so there are no definitive answers to these questions. Despite this dearth of data to guide therapy, clinicians often rely on mood stabilisers when treating patients with BP II. For instance, a study describing prescription patterns for 500 bipolar patients in a US psychiatric academic setting showed that lithium and anticonvulsants play a prominent role in the treatment of BP II patients referred from the community (Ghaemi et al., 2006a). Lithium was prescribed in 36% of that sample, while 30% had been treated with valproate or carbamazepine, and 34% had received second-generation anticonvulsants such as lamotrigine, topiramate or gabapentin (Bauer and Mitchner, 2004; Ghaemi et al., 2006a).

In this chapter we review the evidence for lithium and anticonvulsants specifically for the treatment of BP II Disorder. Though we consider studies that included both BP I and BP II conditions, those studies reporting separate results for BP II are highlighted.

Introduction

Writing in the late nineteenth century, the Prussian psychiatrist Ewald Hecker provided a clinical picture of a form of ‘cyclothymic’ illness manifesting in periods of depression and hypomania that bears a striking resemblance to the contemporary diagnostic category of Bipolar II Disorder (BP II) (Koukopoulos, 2003). Hecker and his senior colleague, Ludwig Kaulbaum, likely influenced Emile Kraepelin's seminal work on ‘manic-depressive insanity’ (Baethge et al., 2003). Kraepelin used the term ‘hypomania’ to refer to non-psychotic, milder forms of mania, which were expressed along a single continuum ranging from purely manic to recurring depressive states (Akiskal and Pinto, 1999; Koukopoulos, 2003). It is not difficult to imagine how a disorder similar to BP II would have fitted within this scheme (Akiskal and Pinto, 1999). Preceding such views by almost 2000 years, Aretaeus of Cappadocia is also known to have described a spectrum of bipolar illness with varying intensities of mania and depression in the first century AD (Goodwin and Jamison, 1990).

Despite these early, and perhaps even seemingly prescient advances, the modern concept of BP II was only first defined in the 1970s by Dunner and colleagues (Dunner et al., 1976). But it was not until the fourth edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM–IV) in 1994 that BP II became officially recognised as a discrete, diagnostic entity (American Psychiatric Association, 1994).