Assessing the pattern electroretinogram as a proxy measure for dopamine in the context of iron deficiency

ABSTRACT

Objectives

Animal studies have suggested that dietary iron deficiency (ID) negatively affects dopamine (DA) synthesis and re-uptake, which in turn negatively affects memory and cognition. This study was intended to assess whether the pattern electroretinogram (pattern ERG) could be used as an indirect measure of DA in college-age women with and without ID by determining the extent to which features of the ERG were sensitive to iron status and were related to other indirect measures of DA.

Methods

The pattern ERG was measured in 21 iron deficient non-anemic (IDNA) and 21 iron sufficient (IS) women, who also performed a contrast detection and probabilistic selection task, both with concurrent electroencephalography (EEG). Both spontaneous and task-related blink rates were also measured.

Results

The implicit times of the A- and B-waves were significantly longer for the IDNA than for the IS women. Both the amplitudes and implicit times of the A- and B-waves were significantly correlated with levels of serum ferritin (sFt). Only the amplitude of the A-wave was correlated with spontaneous blink rate. It was possible to accurately identify a woman’s iron status solely on the basis of the implicit time of the B-wave. Finally, the implicit times of the ERG features mediated the relationship between iron levels and accuracy in the probabilistic selection task.

Conclusions

Results suggest the utility of the pattern ERG in testing the hypothesis that iron deficiency affects DA levels in humans and that this may be one of the mechanisms by which iron deficiency negatively affects cognition.

KEYWORDS:

• pattern electroretinogram‌
• Iron deficiency
• dopamine
• cognition
• learning
• visual perception
• contrast detection‌
• women of reproductive age

Acknowledgement

The data that support the findings of this study are available from the corresponding author [MJW], upon reasonable request. Thanks are due to Sarah Tang, Maddie Cupp, Hudia Jamshed, and Trinity Pruitt for their assistance in collecting the data. This study was not pre-registered.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by University of Oklahoma.

Notes on contributors

Sarah F. Newbolds

Sarah F. Newbolds is a doctoral student in the graduate program in Cellular and Behavioral Neurobiology and Department of Psychology at The University of Oklahoma.

Michael J. Wenger

Michael J. Wenger is a professor in Cellular and Behavioral Neurobiology and Department of Psychology at The University of Oklahoma.