Fatigue in Healthy Individuals
Fatigue in Healthy Individuals
Background:

 -  People with many different diseases have symptoms of fatigue, which is a general sense
 of tiredness; however, the causes are not fully understood. Fatigue symptoms may be
 related to a person s level of fitness, health, and blood chemistries.

 -  Researchers are studying the potential role of plasma cytokines (signaling molecules)
 and hypothalamic-pituitary-adrenal (HPA) axis (part of the neuroendocrine system that
 controls stress) functioning in symptoms of fatigue.

 Objectives:

 -  To characterize the symptoms of fatigue in healthy individuals.

 -  To collect information on fatigue, pain, depression, stress, sleepiness, and quality of
 life from healthy adults of all ages.

 -  To compare results obtained from people with various illnesses to better understand
 possible causes of fatigue that are associated with those diseases.

 Eligibility:

 -  Physically and mentally healthy volunteers18 years of age or older who can speak and
 read the English language.

 -  Exclusion criteria include individuals with a disease or condition causing significant
 fatigue (congestive heart failure, cancer, or sleep disorders), individuals taking
 medicines that cause fatigue (beta blockers, diuretics, or narcotics), and individuals
 who have a major psychiatric condition (major depression, anxiety disorder, or
 schizophrenia).

 -  The following individuals may not participate: those who have two more alcoholic drinks
 per day, who use illicit drugs, or who drink more than 4 cups of coffee, 8 cups of soda
 or tea, or similar amounts of other caffeine-containing beverages a day, or eat more
 than 1 pound of chocolate per day; and individuals who worked evenings or night shifts
 in the past month.

 -  Women who are pregnant or breastfeeding are not eligible.

 Design:

 -  Participants must make two outpatient visits to the Clinical Center. Each visit will
 last 5 hours and participants must refrain from smoking and consuming alcohol and
 caffeine for at least 24 hours.

 -  During the first study visit, researchers will conduct the following tests:

 -  Psychiatric interview, medical history, pregnancy test, and drug test.

 -  Urine test to measure the levels of stress hormones.

 -  Questionnaires that measure fatigue, pain, depression, stress, daytime sleepiness,
 and activity.

 -  Physical fitness test, including strength tests, walking tests, and physical
 activity monitoring.

 -  Before the second study visit, patients must refrain from smoking and consuming caffeine
 and alcohol for at least 24 hours and have nothing, even water, by mouth after midnight.
 During the second study visit, the following tests will be conducted:

 -  Stress hormone test (participant will receive a cortisol-releasing hormone).

 -  Four intravenous blood draws to determine cytokine profiles, gene expression, and
 levels of stress hormones (immune and gentic analysis).

 -  Participants will receive a small financial compensation for participation in the study.
This protocol is designed to characterize the symptoms of fatigue in healthy individuals
 using standardized questionnaires and determine if physical activity, pain, depression,
 fatigue

 catastrophizing, stress, and daytime sleepiness play a role in the experience. This study
 will also examine the potential role of plasma cytokines and hypothalamic-pituitary-adrenal
 axis (HPA) functioning in symptoms of fatigue in healthy individuals.

 Eligible participants will complete questionnaires that measure fatigue, pain, depression,
 fatigue catastrophizing, perceived stress, daytime sleepiness, neurological health, and
 physical activity. Participants will also perform strength testing (e.g. hand grips), walk
 testing (6-minute walk test), exercise testing on a treadmill, and physical activity
 monitoring using a portable activity device. Blood samples will be obtained to determine
 cytokine profiles, gene expression, and levels of stress hormones (cortisol,
 dehydroepiandrosterone [DHEA], catecholamines). Urine samples will also be obtained to
 measure the levels of stress hormones excreted. Information collected in this protocol will
 be used to make comparison in subjects who experience extreme symptoms of fatigue due to many
 different disorders, in order to better understand the mechanisms of fatigue.
-  INCLUSION CRITERIA:

 To be included, participants must meet the following:

 -  Healthy, 18 years of age or older;

 -  Speak and understand the English language.

 EXCLUSION CRITERIA:

 Participants with any one of the following will be excluded:

 -  Inability to provide informed consent for the study;

 -  Are unwilling or unable to cooperate with the study procedures or travel to NIH for
 the procedures;

 -  Have a confirmed medical condition causing clinically significant fatigue symptom
 (e.g. congestive heart failure, cancer actively receiving therapy, sleep disorders);

 -  Currently taking medications that cause fatigue (e.g. diuretics, beta blockers,
 narcotics);

 -  Working late evening and night shifts within the past month;

 -  Have severe psychiatric conditions (e.g. major depressive disorder, bipolar disorder,
 anxiety disorder, schizophrenia, drug and/or addiction abuse or dependence);

 -  Report consuming more than 300mg of caffeine containing beverages (approximately 4
 cups of coffee or 8 cups of soda or tea) or food (approximately 1 lb of chocolate)
 within 24 hours;

 -  Reports consuming more than 2 servings of alcohol containing beverages every day and
 with detectable blood alcohol content (BAC) using breath analyzer (greater than 1
 mg/dL of BAC);

 -  Pregnant or lactating women.

 -  Unable to refrain from smoking at least 4 hours prior to exercise testing sessions

 -  Any medical condition that limits exercise performance (e.g. any condition with a
 ventilatory limitation during maximal exercise)

 -  Any medical condition that affects participants safety with exercise (e.g.: severe
 heart disease, uncontrolled diabetes)