One of the earliest uses of the term ‘spectrum’ in psychiatry was in 1968 for the schizophrenia spectrum.3 However, the mood spectrum comprises a range of functional psychoses, including schizophrenia and schizoaffective and affective disorders.3 Due to its dimensional nature, a spectrum approach towards bipolar disorder has been advocated by some.3 This may offer an alternative to the traditional Kraepelinian distinctions between schizophrenia versus manic–depressive insanity, and unipolar versus bipolar depression.3
References:
1. American Psychiatric Association (APA). Diagnostic and Statistical Manual of Mental Disorders. Fifth edition, text revision. Washington DC: APA; 2022.
2. Vieta E, Berk M, Schulze TG, et al. Bipolar disorders. Nat Rev Dis Primers 2018; 4: 18008.
3. Angst J. The bipolar spectrum. Br J Psychiatry 2007; 190 (3): 189–191.