The reader of this volume has been presented – following an evocative Introduction, and a rich historical overview by Shorter (Chapter 1) – with considerable technical material and some quite contrasting management views for Bipolar II Disorder (BP II). While it is commonly put that medical education should prioritise tolerance of ambiguity, this is more defensible as a principle. In practice, clinicians look for guidelines and consensus to assist their management decisions. While several chapter conclusions appear poles apart from each other (qua ‘bipolar’), there is more consensus than dissent between authors than might have been anticipated, and it is possible to identify many commonalities, reconcile some controversies and identify key areas where research work is required.

How meaningful is the BP II category?

While many would challenge whether BP II actually exists, the majority of this book's authors view BP II as a clinically meaningful category, while the impact of BP II (in terms of disability, economic cost and risk of suicide) argues strongly for its gravity. The consequences of the substantive collateral damage that can occur during the ‘highs’ (affecting relationships, work, finances, reputation, use of drugs and alcohol – and in ways that differ from behaviours during depressed mood states) argues even further for appreciation of the significance of this condition. To suggest that BP II does not exist, or is a slight (or ‘lite’) disorder, no longer appear sustainable propositions.