Bipolar disorders and schizophrenia: discrete disorders?

Area of Science:

• Psychiatry and Neuroscience
• Mental Health Research
• Clinical Psychology

Background:

• Schizophrenia and bipolar disorder exhibit overlapping symptoms, heritability, and neurobiology, prompting debate about their distinctness.
• Understanding the ethiopathogenesis of these disorders is crucial for accurate diagnosis and treatment.
• This review examines shared and unique findings to clarify the relationship between schizophrenia and bipolar disorder.

Purpose of the Study:

• To review and synthesize current evidence on the similarities and differences between schizophrenia and bipolar disorder.
• To explore findings from genetics, neuroimaging, cognition, and clinical course to resolve diagnostic ambiguities.
• To assess whether schizophrenia and bipolar disorder represent a continuum or are separate entities.

Main Methods:

• A narrative literature review was conducted using PubMed and Google Scholar.
• Search terms included "schizophrenia," "bipolar disorder," and terms related to genetics, neuroimaging, cognition, and epidemiology.
• Inclusion criteria focused on English or Spanish full articles comparing schizophrenia and bipolar disorder, or either with healthy controls.

Main Results:

• Evidence supports the heritability and environmental influences on both schizophrenia and bipolar disorder.
• Neuroimaging reveals subtle, patterned irregularities rather than unique markers distinguishing the disorders.
• Cognitive profiles differ, particularly in premorbid intellectual functioning and executive functions, with distinct trajectories of impairment.

Conclusions:

• Current evidence favors schizophrenia and bipolar disorder as separate disorders, despite overlapping features.
• Existing research tools may lack the precision to definitively distinguish between them.
• Future research, potentially utilizing artificial intelligence and Big Data, could help overcome diagnostic uncertainties.