Retinal thickness: A window into cognitive impairment in bipolar disorder

Area of Science:

• Neuroscience
• Ophthalmology
• Psychiatry

Background:

• Cognitive impairment (CI) in bipolar disorder (BD) affects daily functioning.
• Neurobiological markers for CI in BD require further investigation.
• Retinal thickness alterations detected by optical coherence tomography (OCT) show promise in neurodegenerative diseases.

Purpose of the Study:

• To explore OCT's utility in identifying retinal changes associated with CI in BD.
• To enhance understanding of biological markers for BD.
• To supplement neuropsychological testing with objective retinal data.

Main Methods:

• Optical coherence tomography (OCT) measured retinal thickness in 50 BD individuals.
• Specific layers analyzed: macular ganglion cell layer (GCL), inner plexiform layer (IPL), retinal nerve fiber layer (RNFL), and peripapillary RNFL (pRNFL).
• Cross-validated Random Forest models assessed associations with cognitive impairments.

Main Results:

• Significant associations found between retinal thinning in GCL, IPL, and RNFL and CI in BD.
• Retinal changes were particularly relevant to executive function deficits (AUC>0.8).

Conclusions:

• Macular GCL, IPL, and RNFL thinning correlates with poorer cognitive performance in BD.
• Observed patterns are similar to those in schizophrenia, suggesting a potential biomarker.
• This research highlights an innovative field for BD research and clinical applications.