Idiopathic normal pressure hydrocephalus (INPH) is characterized by a classic triad of symptoms including dementia, urinary incontinence, and gait disturbance. INPH is clinically diagnosed in most patients during the sixth or seventh decade of life. Many older adults are incorrectly diagnosed with disorders such as Parkinson's disease and dementia when their symptoms are actually caused by INPH. As life expectancy increases, the necessity of accurately diagnosing and effectively treating these affected individuals will become more challenging. The diagnosis of INPH is challenging and requires a combination of clinical signs and symptoms, radiographic findings, and diagnostic testing. The purpose of evaluation and testing of individuals with suspected INPH is to determine if surgical implantation of a ventriculoperitoneal (VP) shunt will be beneficial. VP shunting is now a common neurosurgical procedure, but it is one associated with risks and complications, which makes evaluation of "shunt-responsiveness" essential.