Blood Pressure Effects on Cognition and Brain Blood Flow in PD

  • End date
    Apr 30, 2025
  • participants needed
  • sponsor
    University of California, San Diego
Updated on 4 October 2022
parkinson's disease
motor symptoms
orthostatic hypotension


Parkinson's disease (PD) is the second most common neurodegenerative disorder worldwide. Besides causing symptoms that impair movement, PD also causes non-motor symptoms, such as problems thinking and orthostatic hypotension (OH), i.e., low blood pressure (BP) when standing. About one-third of people with PD have OH, which can cause sudden, temporary symptoms while upright, including lightheadedness, dizziness, and fainting. People with PD and OH can also experience problems thinking that happen only while upright and not while sitting - this can occur without other symptoms, such as feeling dizzy or faint. However, the level of low BP that can affect thinking remains unknown, and no guidelines exist for treating OH when it happens without symptoms. This is significant because OH could be a treatable risk factor for thinking problems in PD, but OH is often not treated if people do not report obvious symptoms.

This project's goal is to determine how BP affects brain function in PD. The proposed experiments will measure BP and brain blood flow continuously in real-time using innovative wearable technology. People with PD with OH and without OH will undergo repeated cognitive tests while sitting and while upright. I will study the associations between BP, thinking abilities, and brain blood flow, and will compare groups with and without OH. These findings could be important because if a certain level of BP correlates with thinking abilities, then treating OH in PD may prevent thinking problems, which would improve health-related quality of life and reduce disability and healthcare costs.


After reviewing and signing an IRB-approved informed consent, participants will undergo the following clinical assessments for the Screening Visit (duration 3 hours), to determine

  1. complete medical and surgical history including current medication and substance use
  2. general physical and neurological exam
  3. a tilt table test to confirm presence or absence of orthostatic hypotension (OH) OH (defined as systolic BP drop of > 20mmHg or diastolic BP drop of > 10mmHg within 3 minutes of head-up tilt, per consensus criteria (Gibbons et al., 2017)
  4. Orthostatic Hypotension Questionnaire (OHQ) (contains 6 items assessing OH symptoms and 4 items assessing OH symptom burden on daily activities)
  5. Movement Disorders Society Unified Parkinson's Disease Rating Scale
  6. Geriatric Depression Scale 8) head circumference measurements to plan for optimal fitting of the functional near-infrared spectroscopy cap 9) a reading test 10) a test of of global cognition

Baseline Study Visit Procedures: If participants meet all eligibility criteria, after undergoing the screening visit, they will later attend a baseline study visit (duration about 3 hours), which will occur on a separate day. Participants will be instructed to eat a small meal on the day of the visit, abstain from caffeine for 24 hours, and to take all home medications as prescribed. Participants will be encouraged to bring any prescribed antiparkinsonian medications with them to the study visit if it coincides with their usual dosing time, since fluctuations in dopaminergic medications could impact cognitive performance. Upon arrival, after putting on the BP monitor and fNIRS as described below, participants will rest for 20 minutes while sitting to allow for BP stabilization. They will complete the Orthostatic Hypotension Questionnaire (OHQ).

Continuous Non-Invasive BP Monitoring: The CareTaker® is a Food and Drug Administration (FDA)-approved continuous, non-invasive, beat-to-beat BP monitor. This device is worn around the wrist like a watch and uses a sensor attached to an inflatable finger cuff to measure BP by detecting arterial pulsations beneath the skin. The device can continuously monitor BP for up to 24 hours in the ambulatory setting with wireless Internet connection. The CareTaker® uses Bluetooth technology to transmit BP data to a paired electronic Android tablet, automatically logging and documenting BP parameters and waveforms. Data can be accessed immediately on the tablet. variables that will be analyzed. At the start of the visit, the CareTaker® will be placed on the participant's hand that has the least involuntary movement, (e.g., tremor or dyskinesia) to minimize any motion artifact. The BP monitor will be worn during the entire visit and will be removed at the end of the visit. The start and end time of each cognitive task will be recorded and will be time- stamped with an event marker on the Caretaker® to correlate BP with each cognitive task.

This study design was adapted from methods used by Centi et al. to study position-related cognitive changes in PD OH+ and OH-. In this study, participants will perform a cognitive battery while sitting and while upright on a tilt table. The clinical research coordinator will undergo training for all cognitive tests described and will administer the tests. The entire battery will take about 40 minutes. Each cognitive task will be administered twice: once while sitting and once while upright (at 60o) on a tilt table.

Cognitive testing will be split into four 20-minute sessions: two 20-minute sessions in the sitting position and two 20-minute sessions in the upright position. The cognitive testing sessions will be alternated between sitting and upright positions (i.e., sitting, upright, sitting, upright (Group A); or upright, sitting, upright, sitting (Group B). Participants will be randomized to Group A or Group B. After the upright testing sessions, the participant will be lowered to sitting and will rest sitting until systolic and diastolic BP returns to within 10mmHg of the baseline BP before beginning the sitting cognitive testing. Cognitive tasks with visual components will be adapted to the sitting and upright positions by using a projector to display the tests on a screen. After the testing, participants will be released from the tilt table, and the fNIRS and Caretaker® will be removed.

Functional near-infrared spectroscopy (fNIRS) is a non-invasive, wearable technology that applies distinct near-infrared light wavelengths into the scalp to measure changes in the color of blood, since oxy- hemoglobin (HbO) absorbs light differently than deoxy-hemoglobin (Hb). Activation of neurons (e.g., in response to a cognitive task) increases brain tissue's metabolic demand, which increases regional cerebral blood flow, leading to increased HbO and decreased Hb. To detect these changes, fNIRS sources emit light, which are paired with light detectors to penetrate regions of brain cortex. Collectively, these probes are arranged in custom montages, which are worn on a head cap. Advantages unique to fNIRS are its safety, portability, and ability to study brain blood flow in different positions. The proposed research will use a 16-channel, 16-detector system, the NIRSport2 (NIRx®). During the sitting and upright cognitive testing described above, participants will wear an fNIRS cap with probes arranged over the right brain to optimize evaluation of visuospatial function, since language is left-hemisphere dominant in most people. Real-time cerebral oxygenation changes will be measured continuously throughout the study visit, including during cognitive tasks. I will collect baseline data for 30 seconds in each position before beginning cognitive testing. The continuous recordings from the fNIRS and the CareTaker® will be time-stamped by tapping both sensors simultaneously, which will allow later time synchronization of the multi-sensor data. The start and end of each cognitive task will be time-stamped on the fNIRS by using an automated time synchronization event marker to later correlate HbO and Hb changes with each cognitive task during data analysis. The fNIRS will be removed at the end of the visit.

Condition Parkinson Disease, Orthostatic Hypotension, Dysautonomia
Treatment Tilt table (upright position)
Clinical Study IdentifierNCT05400174
SponsorUniversity of California, San Diego
Last Modified on4 October 2022


Yes No Not Sure

Inclusion Criteria

diagnosis of idiopathic Parkinson Disease using the Movement Disorders Society (MDS) Clinical Diagnostic Criteria
age > 50 years old
Hoehn & Yahr (H&Y) stages I-III (early to moderate-stage PD; able to walk without assistance
proficiency in the English language (native English speaker level)

Exclusion Criteria

any involuntary movements (i.e., tremor or dyskinesia) > 3 cm in amplitude (ok if movements are treated with medication), since the motion artifact could interfere with blood pressure monitor data collection
dementia (including PD dementia)
status post deep brain stimulation (DBS)
any unstable, active medical problem, e.g. decompensated heart failure, liver failure, etc.; 5) moderate or severe carotid artery stenosis (according to North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria)
history of cerebral infarction or hemorrhage 7) uncontrolled diabetes or any other systemic disease causing autonomic failure; 8) syncope (fainting) within the past week 9) illiteracy 10) taking antihypertensive medications or alpha-adrenergic blocking medications, since these can cause hypotension 11) impairment of hearing or vision that is not corrected by devices (e.g., hearing aids or glasses) 12) currently pregnant (will be confirmed by women of child-bearing potential with urine pregnancy test) 13) any other condition, which, in the opinion of the investigator, could place the participant at increased risk
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