Kim Annink

105 The long-term effect of perinatal asphyxia on hippocampal volumes the reference standard of 100, which is likely to be explained by the fact that their mothers had a higher educational level than the average population. This might partially explain the difference in IQ between children with HIE and healthy controls. It is well known that infants with HIE have an increased risk of developing cognitive deficits, even in the absence of motor deficits (4,5). In a follow-up study of Robertson et al. 40% of the children with moderate HIE without neurological deficits had an impaired IQ and delayed learning skills at 8 years of age in comparison to controls (5). Similarly, Steinman et al. showed that 9% of the children following HIE without motor problems had a verbal IQ <70 at 4 years of age (35). Besides IQ, memory also has been shown to be affected in children with HIE (9,10). Mañeru et al. found that children with moderate HIE have impaired verbal and visual memory compared to mild HIE and controls (9). It was thought for many years that only infants with moderate and severe HIE are at risk for cognitive impairment (4–6,8,9,26). However, a possible trend of impaired memory function and IQ in mild HIE has been suggested recently (10,12,17). In a large Swedish cohort, even infants with Apgar scores <7 without encephalopathy had an increased risk of an impaired IQ at 18 years of age (36). The observed predominant deficits in episodic memory in our cohort are in line with the literature (6,8,10,26). Semantic memory is relatively spared in HIE. It is hypothesized that semantic memory depends on the hippocampus and the temporal cortices, but that a spared temporal cortex is sufficient to compensate for hippocampal damage and to develop normal semantic memory functions (37). On the contrary, episodic memory seems to depend fully on the development of the hippocampus and is therefore more affected by hippocampal damage (37,38). To study the association between HIE, hippocampal volumes and cognition, we first showed that HIE is an important predictor of hippocampal volumes using multivariable linear regression analysis. Next, we studied how the hippocampal volume is associated with IQ and memory using multivariable linear regression. Based on previous reports, we expected reduced hippocampal volumes to be associated with long-term episodic memory impairment (6,38). However, after correcting for age, sex and SES, the percentage hippocampus/ICV was only strongly associated with the episodic subtests for visuospatial long-term memory. In a larger cohort the effect of hippocampal volume on other subtests for long-term episodic memory would maybe also have been significant. The effect of hippocampal volume 5