An investigation of working memory deficits in depression using the n -back task: A systematic review and meta -analysis

Background: Depression is associated with cognitive deficits across multiple domains, including working memory. The n-back task, a convenient psychometric tool capable of computerised delivery and concurrent use with neuroimaging, can provide enhanced insight into working memory dysfunction in depression. This meta-analysis sought to investigate the n-back task under varying cognitive load conditions (i.e. different levels of 'n') to clarify the pattern of working memory deficits in depression. Methods: We conducted a systematic review and meta-analysis of studies involving unipolar depressed participants and matched controls utilising the n-back task. Meta-analyses were performed for accuracy and response times at four levels of cognitive load (0-, 1-, 2-, and 3-back). Results: 31 studies (total 1,666 participants) met inclusion criteria and were included for quantitative analyses. Depressed individuals had significantly reduced accuracy compared to controls for 1-, 2-, and 3-back tasks, but not the attentional 0-back task. Likewise, response latencies were prolonged for all task levels (0-, 1-, 2-, and 3 back). Additional meta-regression analyses indicated that participant age and clinical status (i.e. inpatient/ outpatient) may exacerbate working memory deficits associated with depression. Limitations: Our results indicate high levels of heterogeneity between studies, particularly for response times. Conclusions: Accuracy impairments were worse at higher levels of n, with the largest effect size obtained on the 2 back task, suggesting deficits to higher executive functions. Response times were consistently prolonged at all cognitive loads in agreement with a pattern of generalised psychomotor retardation.

Automated summary

This meta-analysis found that individuals with depression exhibit working memory deficits in n-back tasks, showing decreased accuracy and prolonged response times, especially under higher cognitive loads. Participant age and clinical status may exacerbate these deficits.