Decreased cerebrovascular compliance is a descriptive term used in transcranial color Doppler ultrasound to describe the possibility of atherosclerosis of the cerebral blood vessels, which may be accompanied by atherosclerotic plaque formation in severe cases. Atherosclerosis results in a decrease in the elasticity of the blood vessel wall, which decreases its ability to contract and dilate, and decreases compliance when the blood flow passes through and does not adjust in time to the dilation and contraction of the blood pressure. The most common causes of atherosclerosis are the three highs, i.e., hypertension, hyperglycemia, and hyperlipidemia. In addition, there are also hyperfibrinogenemia, hyperhomocysteinemia and bad habits such as smoking and drinking. When this happens, the patient has to be actively examined for risk factors, to identify what causes the reduced vascular compliance and to prevent it. It is important to note that even in the absence of these risk factors, the compliance of the vessel wall is significantly reduced in patients who have reached a certain age, for example, 60 or 80 years or older.