European Study of Prodromal iNPH

Inclusion criteria - Group 1 - prodromal iNPH * Brain imaging with both: * Evans index \> 0.3 * Callosal angle ≤ 90 º or: * Disproportionately enlarged subarachnoid space hydrocephalus (DESH) - defined as: enlarged ventricles, dilated sylvian fissures and tight sulci at the high convexity. * Absence of symptoms or too mild symptoms to motivate shunt surgery according to local routine, and all of the following: * Normal gait pattern, or slight disturbance of the gait pattern that is not considered to be caused by a disease in the central nervous system (CNS). * Gait velocity (maximum gait speed), men ≥ 1.4 m/s; women ≥ 1.25 m/s. * Rombergs test with eyes open \> 60 seconds * Mini Mental State Examination (MMSE) ≥ 27 or Montreal Cognitive Assessment (MoCA) ≥ 23 * Informed consent Exclusion criteria - Group 1 - prodromal iNPH * Contraindication for MRI * Other serious disease with expected survival less than three years * Other type of hydrocephalus: * non-communicating hydrocephalus * secondary communicating hydrocephalus * suspected congenital hydrocephalus (severely enlarged ventricles, narrow sylvian fissures and normal non-compressed sulci at the high convexity or morphological findings consistent with PaVM18) * Anticoagulants in a dose that hinders lumbar puncture Inclusion criteria - Group 2 - healthy controls • Age \> 65 years Exclusion criteria - Group 2 - healthy controls: * Imaging findings meet inclusion criteria of Group 1 * Previously known relevant neurological disease * Pathological gait pattern with unknown reason. * MMSE \< 27 or MoCA \< 26. * Anticoagulants in a dose that hinders lumbar puncture Inclusion criteria Group 3 symptomatic iNPH * iNPH diagnosis according to international guidelines.19 * Age matched with the individual in Group 1 (+/- 3 years) Exclusion criteria Group 3 symptomatic iNPH * Previous stroke (clinical stroke, not only radiologically verified) * Other serious disease with expected survival less than three years