The study will examine urinary sodium excretion induced by psychological stress and its diurnal pattern as a novel biological mechanism that may underlie an abnormal diurnal pattern of blood pressure. The study will test the hypotheses that lower stress-induced sodium excretion is associated with an abnormal diurnal pattern of sodium excretion, and that an abnormal diurnal pattern of sodium excretion is associated with an abnormal diurnal pattern of blood pressure. Primary Aim 1: To examine the association between urinary sodium excretion after provoked psychological stress and the diurnal pattern of sodium excretion. Primary Aim 2: To examine the association between the diurnal pattern of sodium excretion and the diurnal pattern of BP. Secondary Aim: To examine whether the association between urinary sodium excretion after provoked stress and the diurnal pattern of sodium excretion is modified by ecological momentary levels of perceived stress, experienced during the daytime period. Exploratory Aim: To determine the socio-demographic, behavioral, and psychological traits, chronic stress, and biological stress-related factors that are associated with lower stress-induced sodium excretion. Identification of these factors will help determine who is at risk for having a differential sodium excretion response to psychological stress.
Blood pressure (BP) has a diurnal rhythm; it is normally highest during the daytime period and lowest during the nighttime period (BP dipping). The diurnal pattern of BP over a 24-hour period can be assessed using ambulatory BP monitoring (ABPM). Evidence indicates that an abnormal diurnal pattern of BP on ABPM, defined by reduced BP dipping or elevated nighttime BP, is associated with an increased risk of cardiovascular disease (CVD) events. Psychological stress occurs when an individual perceives that the environmental demands exceed his/her adaptive capacity. An individual's response to events that are representative of this overload, such as perceived stress and negative affect including anger, hostility, depression, vital exhaustion, and symptoms of posttraumatic stress disorder, are associated with reduced BP dipping and/or higher nighttime BP. Exposure to environmental factors which tax an individual's ability to cope, including lower socioeconomic status, job strain, and perceived racism, are also associated with reduced BP dipping and/or higher nighttime BP. This study will examine the disruption of the normal diurnal pattern of sodium excretion by psychological stress as a novel biological mechanism underlying an abnormal diurnal pattern of BP. The study will be conducted both in the laboratory and in the naturalistic environment with a multi-ethnic sample of 211 adult community participants from upper Manhattan who do not have a history of CVD, diabetes, chronic kidney disease, or another major medical condition and are not taking antihypertensive medication. During a laboratory visit, urinary sodium excretion in response to mental stress tasks will be examined.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
OTHER
Masking
NONE
Enrollment
323
All enrolled participants who attended the laboratory visit underwent stress-inducing tasks (psychological stress) using validated research tools. Participants performed a 5-minute computer Stroop Color Test and a 5-minute verbal Mental Arithmetic Task. The research assistant asked the participant to work as quickly and accurately as possible for both tasks.
Columbia University Medical Center - Shimbo Hypertension Lab
New York, New York, United States
Ratio of Awake-to-asleep Urinary Sodium Excretion Rate (Aim 1)
Time frame: Over 24-hour ambulatory period
Systolic Blood Pressure Dipping (Aim 2)
Systolic blood pressure (SBP) dipping refers to the normal physiological decline in SBP during nighttime sleep. SBP dipping (%) was calculated as 100 \* (mean awake SBP - mean asleep SBP) / (mean awake SBP).
Time frame: Over 24-hour ambulatory period
Mean Perceived Stress Level
This is to measure the ecological stress level for the awake period during which the participants' sodium excretion is monitored. A 10-point Visual Analog Scale (VAS) (0=Not at all, 5=Moderately, and 10=Extremely) was used to assess stress.
Time frame: Over 24-hour ambulatory period
24-hour Sodium Excretion
Rate of sodium excretion, measured from urine collected from participants during the ambulatory period.
Time frame: Over 24-hour ambulatory period
24-hour Potassium Excretion
Rate of potassium excretion, measured from urine collected from participants during the ambulatory period.
Time frame: Over 24-hour ambulatory period
24-hour Creatinine Clearance
Rate of creatine clearance, measured from urine collected from participants during the ambulatory period.
Time frame: Over 24-hour ambulatory period
Fractional Excretion of Sodium
Fractional excretion of sodium is the amount of sodium that leaves the body through urine compared to the amount filtered and reabsorbed by the kidney.
Time frame: Over 24-hour ambulatory period
EMA Stress
10-point Ecological Momentary Assessment (EMA) measures self-reported stress through a questionnaire (0=Not at all, 5=Moderately, and 10=Extremely). Higher score indicates worse stress. The average EMA score over 5 time points in a 24-hour ambulatory period are reported.
Time frame: Over 24-hour ambulatory period
EMA Anger
10-point Ecological Momentary Assessment (EMA) measures self-reported anger through a questionnaire (0=Not at all, 5=Moderately, and 10=Extremely). Higher score indicates worse anger. The average EMA score over 5 time points in a 24-hour ambulatory period are reported.
Time frame: Over 24-hour ambulatory period
EMA Aggravation
10-point Ecological Momentary Assessment (EMA) measures self-reported aggravation/irritation through a questionnaire (0=Not at all, 5=Moderately, and 10=Extremely). Higher score indicates worse aggravation. The average EMA score over 5 time points in a 24-hour ambulatory period are reported.
Time frame: Over 24-hour ambulatory period
EMA Anxiety
10-point Ecological Momentary Assessment (EMA) measures self-reported anxiety through a questionnaire (0=Not at all, 5=Moderately, and 10=Extremely). Higher score indicates worse anxiety. The average EMA score over 5 time points in a 24-hour ambulatory period are reported.
Time frame: Over 24-hour ambulatory period
EMA Depressed
10-point Ecological Momentary Assessment (EMA) measures self-reported sadness/depression through a questionnaire (0=Not at all, 5=Moderately, and 10=Extremely). Higher score indicates worse depression. The average EMA score over 5 time points in a 24-hour ambulatory period are reported.
Time frame: Over 24-hour ambulatory period
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