MR Evaluation of Cerebrospinal Fluid (CSF) Dynamics

Inclusion Criteria:

* A healthy control will be defined as an otherwise healthy person who does not have a medical condition that affects brain function or have problems with concentration, memory, balance, or coordination.
* Patients who have a suspected diagnosis of altered CSF dynamics including but not limited to normal pressure hydrocephalus will be referred to Dr. Cogswell by their care team to be included in the study. Conditions of altered CSF dynamics include obstructive and non-obstructive hydrocephalus and may be associated with headaches and/or decreased cognitive function.
* Similarly, patients with impaired cognitive function including but not limited to Alzheimer's disease will be referred to Dr. Cogswell by their care team to be included in the study.

Exclusion Criteria:

* Subjects with non-MRI compatible devices
* required sedation
* women who may be pregnant will be excluded.
* The first 10 subjects with normal pressure hydrocephalus will not have previously been shunted.