Résumé
This chapter traces the concept of bipolar spectrum to its origin and details its current classification and epidemiology. Based on the findings of different surveys, it shows how much conceptual developments could be linked to a growing focus on misdiagnosis issues, including consequences of and contributors to misdiagnosis in bipolar illness. Differential diagnosis is subsequently addressed with major depressive disorder, anxiety disorders, psychotic disorders, personality disorders, and other issues such as substance abuse, attention deficit hyperactivity disorder (ADHD), and dementia. The last part reviews the screening tools, diagnostic instruments, and interviews that may help clinicians to improve the diagnosis of bipolar spectrum disorders.