Mnemonic Discrimination Performance in Anxiety and Depression: A Systematic Review

Anxiety disorders and depression are the most frequently diagnosed mental illnesses and are highly comorbid. Both have been linked to memory impairments, albeit the relationship between them remains unclear and understudied. Our review aims to investigate behavioral pattern separation performance in individuals with varying levels of anxiety and depression. We included studies where mnemonic discrimination performance is measured using mnemonic discrimination tasks designed to directly measure behavioral pattern separation, while symptoms of anxiety and/or depression are assessed using any validated and recognized scales or inventories. We only included quantitative studies. Fixed scientific databases and artificial intelligence were systematically searched, identifying nine studies on anxiety and 14 on depression. Anxiety studies presented conflicting evidence, but a trend showed optimal mnemonic discrimination with threat-based encoding and safe retrieval. Conversely, depression studies consistently suggested a negative relationship between symptom severity and pattern separation performance. Additionally, pattern separation appeared enhanced for negative stimuli and impaired for neutral stimuli in individuals with higher levels of depression. However, no clear differences were observed between clinically diagnosed groups and healthy controls. Methodological inconsistencies in anxiety studies present challenges for interpretation. Similarly, the effects of medication and the heterogeneity of clinical groups pose limitations to depression studies. Trends were identified, but further investigation with unified methodologies and clinical groups is needed to understand the relationship between anxiety, depression, and mnemonic discrimination performance.