IGF1 and early-onset autosomal dominant Alzheimer disease: Other authors have demonstrated levels of CSF IGF-1 in elderly control subjects of 4.30–4.40 pg/ml [60,61], and in elderly cohorts with Alzheimer's disease of 9.44 pg/ml [61], so it is possible that the ELISA we used was not sufficiently sensitive to detect IGF-1 in this setting.