Iron deficiency in infancy and neurocognitive functioning at 19 years: evidence of long-term deficits in executive function and recognition memory

Abstract

Iron deficiency in infancy negatively impacts a variety of neurodevelopmental processes at the time of nutrient insufficiency, with persistent central nervous system alterations and deficits in behavioral functioning, despite iron therapy. In rodent models, early iron deficiency impairs the hippocampus and the dopamine system. We examined the possibility that young adults who had experienced chronic, severe, iron deficiency as infants would exhibit deficits on neurocognitive tests with documented frontostriatal (Trail Making Test, Intra-/Extra-dimensional Shift, Stockings of Cambridge, Spatial Working Memory, Rapid Visual Information Processing) and hippocampal specificity (Pattern Recognition Memory, Spatial Recognition Memory). Participants with chronic, severe iron deficiency in infancy performed less well on frontostriatal-mediated executive functions, including inhibitory control, set-shifting, and planning. Participants also exhibited impairment on a hippocampus-based recognition memory task. We suggest that these deficits may result from the long-term effects of early iron deficiency on the dopamine system, the hippocampus, and their interaction.

Figure 1

Number of switching, non-switching, and total errors made on Part B of the Trail Making Test as a function of iron status in infancy (‡ p < .05).

Figure 2

Mean initial thinking time as a function of iron status in infancy and problem difficulty on the Stockings of Cambridge subtest of the CANTAB. Significant group differences for a given level of problem difficulty are indicated (‡ p < .05).

Figure 3

Mean number of moves required to successfully solve problems as a function of iron status in infancy and problem difficulty on the Stockings of Cambridge subtest of the CANTAB. Significant group differences for a given level of problem difficulty are indicated (‡ p < .05).

Figure 4

Predicted probability of participants who attempted and passed the final two stages of the Intra-/Extra-dimensional Shift task of the CANTAB as a function of iron status in infancy. Marginal group differences are indicated (■ p = .10).

Figure 5

Predicted relations between mean latency to make correct responses and the percent of correct responses as a function of iron status in infancy on the Pattern Recognition Memory subtest of the CANTAB. Significant group differences are indicated (‡ p < .05).