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, patient’s 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.
• Subjects with required sedation.
• Women who may be pregnant.