Association between high biomarker probability of Alzheimer's disease and improvement of clinical outcomes after shunt surgery in patients with idiopathic normal pressure hydrocephalus

We examined the effect of the pathology of Alzheimer's disease (AD) on improvement of clinical symptoms after shunt surgery in patients with idiopathic normal pressure hydrocephalus (iNPH). Forty-four iNPH patients were classified into 18 patients with (iNPH/AD +) and 26 patients without (iNPH/AD −) combination with low amyloid β42 and high total tau in cerebrospinal fluid (CSF). We compared improvements after lumbo-peritoneal shunt surgery (LPS) between the two groups in Timed Up & Go Test, 10-m reciprocating walking test, Digit Symbol Substitution Test, attention test, delayed recall test, Mini-Mental State Examination, iNPH grading scale, Neuropsychiatric Inventory, Zarit Burden Interview, and other evaluations. Three months after LPS, gait, urination, overall cognition, psychomotor speed, attention, and neuropsychiatric symptoms significantly improved in both groups, but the improvement in delayed recall and reduction of caregiver burden were significantly greater in iNPH/AD − than iNPH/AD +. In addition, improvement in delayed recall score after LPS was significantly and negatively correlated with the probability of AD as judged by amyloid β42 and total tau levels in CSF. Three months after LPS, almost all of the triad symptoms decreased in iNPH patients with and without AD pathology but memory improved only in iNPH patients without AD pathology.