Recently, sympathetic hyperactivity was detected in patients with TAD [7], further investigation revealed that noradrenaline (NE) release from sympathetic nerve endings would up-regulate matrix metalloprotease 2 (MMP2) expression in thoracic aorta which may lead to ECM reconstruction [8], these results showed a direct correlation between ANS and AD. The gene discussed is MMP2; the disease is Alzheimer disease.