Brain atrophy does not necessarily cause Alzheimer’s disease, and the two are not necessarily related. Brain atrophy refers to the reduction of brain volume, physiological brain atrophy can be obvious with the patient’s age, clinical symptoms may not be obvious, imaging may show deepening of the brain sulcus. The onset of Alzheimer’s disease is related to the abnormal deposition of β-amyloid in the brain. β-amyloid has a toxic effect on the synapses and neurons around it, which can destroy the synaptic membrane and ultimately cause the death of nerve cells. Alzheimer’s disease can be manifested by CT as hippocampal or frontal parietal lobe atrophy, but this point is not the only diagnostic criterion. So brain atrophy is not equivalent to Alzheimer’s disease, but certain vascular lesions, which cause insufficient blood supply to the brain, may appear as brain atrophy and can also affect intelligence.