Slow reaction speed may be caused by ageing, recent overwork and other physiological factors; may also be suffering from cerebral vascular sclerosis, neurasthenia and other diseases. 1. Physiological factors: after ageing, the elderly brain cells will slowly die, may appear slow reaction speed, memory loss, loss of symptoms, which is a normal phenomenon. Secondly, if they have been overworked recently and do not have enough sleep, the symptoms of slow reaction speed may also occur. 2. Cerebral vascular sclerosis: genetic factors, obesity or hypertension, hyperlipidemia and other diseases may induce cerebral vascular sclerosis, resulting in slow reaction speed, headache, blurred vision, tinnitus and other symptoms. 3. Neurasthenia: long-term mental stress, prolonged mental work, may induce neurasthenia, resulting in patients with slow reaction speed, dizziness, headache, mental instability, insomnia and other symptoms. If the reaction speed is slow, after excluding physiological factors, it is recommended that the patient to the hospital to follow the doctor’s instructions for relevant examinations, to clarify the cause of the disease, and receive treatment as soon as possible.