Normal pressure hydrocephalus (NPH) is a potentially reversible cause of dementia. It is characterized by a triad of gait disturbance, urinary incontinence, and cognitive impairment. Gait disturbance is the most common and responsive to treatment, making "treatable gait disorder" a more accurate description. Diagnosis requires imaging evidence of ventricle enlargement without obstruction and presence of at least two of the three clinical symptoms. Compared to Alzheimer's disease and vascular dementia, NPH shows more prominent enlargement of the lateral and third ventricles, aqueduct, and fourth ventricle on MRI. Lumbar puncture typically shows normal opening pressure. Shunt surgery can improve symptoms if performed early.