A common complaint among people with Postural Tachycardia Syndrome (POTS) is "brain fog" or difficulty concentrating. This is very poorly understood. To better understand this cognitive dysfunction, the investigators will test people with POTS and people without POTS using various neuropsychiatric instruments. The investigators hypothesis is that people with POTS will have greater abnormalities on neuropsychiatric testing than normal controls.

Postural Tachycardia Syndrome (POTS) is a disorder that affects an estimated 500,000 people in the United States alone and is an important source of disability in young adults. It shows a strong predilection for females. POTS is a form of orthostatic intolerance characterized by an excessive increase in heart rate (>30 bpm) on assuming the upright position associated with orthostatic symptoms, but in the absence of orthostatic hypotension. Their symptoms of dizziness, nausea, tremor, chronic fatigue and exercise intolerance make even simple activities of daily living exhausting prospects.

Brain fog or cognitive dysfunction is a common and almost universal complaint among persons with POTS. There is a lack of pathophysiological understanding to this cognitive dysfunction and is also a major roadblock to the development of effective therapies for people with POTS.

The purpose of this study is to better define the cognitive dysfunction seen in patients with POTS. We will use a series of validated neuropsychological tools in order to characterize POTS cognitive dysfunction and compare this data to age and gender matched control subjects.

Specific Aims:

1. To assess whether POTS patients have more neuropsychological abnormalities than control subjects during seated assessments.
2. To assess whether POTS patients have more neuropsychological abnormalities than control subjects during assessments while standing.
3. To ascertain the phenomenology of any neuropsychological deficits distinguishing POTS patients from controls.

Inclusion Criteria:

All

• Ages between 18-60 years
• Male and female subjects are eligible
• Able and willing to provide informed consent

POTS - additional inclusion criteria - Diagnosed with postural tachycardia syndrome by Vanderbilt Autonomic Dysfunction Center (increase in heart rate greater than or equal to 30 beats per minute with position change from supine to standing (10 minutes; chronic symptoms consistent with POTS that are worse when upright and get better with recumbence.)

Control subjects - additional inclusion criteria

• Gender matched to POTS patients
• Age-matched to POTS patients (+/- 5 years of a POTS patient)
• Grossly matched in intelligence to POTS patients

Exclusion Criteria:

ALL

• Inability to give or withdrawal of informed consent
• Pregnancy (determined by patient self report)
• Other factors which in the investigator's opinion would prevent the subject from completing the protocol.

POTS - additional exclusion criteria

- Overt cause for postural tachycardia (such as acute dehydration)

Normal Controls - additional exclusion criteria

• Previously diagnosed with Axis I psychiatric disorder
• Previously diagnosed learning disorder
• Previously diagnosed attention deficit hyperactivity disorder (ADHD)
• Prior psychosis
• past or present substance abuse
• History of loss of consciousness
• History of seizures

Patients having been diagnosed with postural tachycardia syndrome and age & gender matched normal controls