fMRI in Postural Tachycardia Syndrome

Postural tachycardia syndrome (POTS) is one of the most common forms of chronic orthostatic intolerance in the United States. This is a disabling disorder characterized by an excessive increase in heart rate upon standing that is accompanied by symptoms such as dizziness and fatigue. One of the most under appreciated and bothersome symptoms of POTS is impaired cognition or "brain fog," which occurs to a level that interferes with daily activities such as work and education. Despite this high impact, the reasons why POTS patients have problems with cognition are not well understood. This project will test the overall hypothesis that "brain fog" in POTS is related to increased activation of cognitive brain regions during mental tasks when compared with healthy subjects, and that this activation is exacerbated by in the presence of orthostatic stress.

Inclusion Criteria: * Men and women of all races or ethnicity * Age 18-60 * Healthy volunteers or previously diagnosed with POTS by current consensus criteria (rise in heart rate of at least 30 beats/minute within 10 minutes of standing; absence of orthostatic hypotension defined as a drop in blood pressure greater than 20/10 mmHg within 3 minutes of standing; and presence of daily orthostatic symptoms for at least 6 months such as lightheadedness, dizziness, nausea, and palpitations). * Healthy participants must have cognitive testing scores within normal range (defined by Stroop word-color test score between 40-70) and be able to tolerate lower body negative pressure. * POTS participants must have either mild cognitive dysfunction (defined by Stroop word-color t-score \30) or normal cognitive function (defined by Stroop word-color test score between 40-70), and able to tolerate lower body negative pressure. * Capable of giving informed consent * Fluent in written and spoken English Exclusion Criteria: * Age \60 years * Pregnant or breastfeeding women * Left handedness * Require glasses for vision correction (contact lenses are okay) * Current smokers * Alcohol or drug abuse * Recreational drug use (e.g. cannabis, heroin, cocaine) * Other potential causes for tachycardia (e.g. prolonged bed rest, dehydration) * Taking selective norepinephrine reuptake inhibitors or stimulant medications within the past 3 months as these may alter cognition * Unable to tolerate an MRI scanner (e.g. claustrophobia, implanted metal) * Unable to give or withdraw informed consent