Mammillary body abnormalities and cognitive outcomes in children cooled for neonatal encephalopathy.

The analysis included only 32 cooled children and 35 controls, so the study may have missed smaller differences, especially in tract diffusion measures. The children were aged 6 to 8, spoke English, were born after 35 weeks, had no additional diagnoses and had no cerebral palsy, so results may not apply to younger, non-English-speaking, preterm, medically complex or cerebral palsy groups. Mammillary body abnormalities were assessed visually and grouped as normal, equivocal or abnormal, so mild differences may be underdetected. The study was cross-sectional and observational, so it cannot show that mammillary body abnormalities caused cognitive differences or that cooling caused the abnormalities. Controls were recruited from schools around Bristol, so they may not represent all typically developing children. The study tested several cognitive and brain measures, so some findings may be unstable.

Charitable funds and research councils supported the work: Baily Thomas Charitable Fund, David Telling Charitable Trust, Sparks, Moulton Foundation, Wellcome Trust and UK Medical Research Council. The authors declared no conflicts of interest or bias.

Do not conclude that therapeutic hypothermia caused mammillary body abnormalities or cognitive impairment. The study compared cooled children with controls at 6 to 8 years and found associations, but it did not establish cause, and only 11 of 32 analysed cooled children had abnormal mammillary bodies.