(P27-041-23) Assessing the Pattern Electroretinogram as a Proxy Measure for Dopamine in the Context of Iron Deficiency

Objectives: Animal models of the cognitive deficits associated with iron deficiency (ID) have consistently pointed to dysregulation of dopamine synthesis and reuptake. The hypothesis that dopamine dysregulation is functional in human ID has not been tested directly due to technical challenges. The present study assesses the extent to which the pattern electroretinogram (ERG) is useful as a proxy measure of central dopamine. For this to be true, features of the pattern ERG would minimally need to be related to other established proxy measures of dopamine (blink rate) and blood biomarkers of iron status.

Methods: A total of 20 ID (serum ferritin < = 16 ug/L) non-anemic (hemoglobin > 12 g/dL) and 20 iron sufficient were recruited for an approximately 2 hr testing session in which they completed four tasks. The first was a pattern ERG task, which involved the presentation of black and white checkerboards of alternating contrast. Participants viewed these stimuli while small electrodes were affixed to the bottom lid of each eye in order to measure the signals generated in the retina. The second task was a passive viewing task in which participants fixated a centrally presented character for five minutes. Concurrent electroencephelographic (EEG) data were collected and were used to determine blink rate. The third task was a probabilistic selection task, which has been shown to be sensitive to variations in dopamine levels. The fourth task was a contrast detection threshold task which we have shown to be sensitive to variations in iron levels.

Results: Blink rate, an established proxy measure of dopamine, was reliably (r = 0.35, p < .05) related to serum ferritin (sFt). Blink rate was also reliably related to the peak amplitude of the negative-going A-wave of the ERG (r = -0.52, p < .01). Critically, both the peak amplitudes and peak latencies of the A- and B-waves of the ERG were reliably related to sFt (all p < .05).

Conclusions: Features of the ERG were reliably related to established proxy measures of dopamine and iron status. This suggests the utility of the ERG in relating animal models of iron deficiency ID-related cognitive deficits in humans.

Funding Sources: Funding was provided by the University of Oklahoma Vice President for Research and Partnerships and by the Dodge Family College of Arts and Sciences.