IGF1 and injury: The somatotopic axis (including IGF-1) appears to be affected in brain injury, and given its role in stimulating protein synthesis in neurons and glial cells, may play a role in preventing secondary injury following trauma.18,19 In this cohort of Veterans and Service Members, increased levels of IGF-1 significantly reduce the number of WMHs, even when controlling for age (one of the primary drivers of WMHs in this study), which may provide support for this idea.