With evidence suggesting that the HPA-axis may be dysfunctional in children with ADHD (Hong et al. 2003), and intriguing findings indicating for a molecular interactive link between the brain’s cholinergic systems and the HPA-axis neuroendocrine system in modulating cognitive processes (Paul et al. 2015), we also determined for possible defective HPA-axis activity in ChAT::Cre+ compared to Wt siblings, in response to fear conditioning. Here, CHAT is linked to attention deficit-hyperactivity disorder.