Clinical Evaluation of Montelukast in Veterans With Gulf War Illness

Inclusion Criteria:

* Gulf War Veterans of the U.S. military deployed on military orders to the Persian Gulf Region between August 2, 1990, and December 31, 1991
* Diagnosed with GWI according to the CDC and modified Kansas criteria as recommended by the Institute of Medicine (IOM), that is, endorse multiple or moderate-to-severe symptoms, with symptom onset during or after deployment to the Persian Gulf region in 1990-1991, persisting for six months or longer, in at least 3 of 6 domains:

  1. fatigue/sleep disturbances
  2. neurological/cognitive/mood symptoms
  3. somatic pain
  4. gastrointestinal problems
  5. respiratory symptoms
  6. skin symptoms
* Self-reported cognitive dysfunction based on a T-score of 40 or less on the PROMIS v2.0 Cognitive Function 8a short form
* Be able to:

  * provide written consent and be able to communicate with the research team in verbal and written English
  * attend the two in-person study encounters
  * have reliable telephone service for the eight weekly telephone encounters

Exclusion Criteria:

* Diagnosed by a physician with any chronic condition that may explain their profile of symptoms or prevent their ability to accurately report them including:

  * chronic autoimmune conditions
  * systemic inflammatory conditions
  * cancer not in remission at least 5 years
  * congestive heart failure
  * anemia
  * multiple sclerosis
  * amyotrophic lateral sclerosis (ALS)
  * poorly controlled diabetes
  * post-chemo or radiation syndromes
  * sickle cell anemia
  * symptomatic Coronary Artery Disease (CAD)
  * chronic liver disease
  * chemical insufficiency
  * morbid obesity (body mass index (BMI) \>= 40)
  * human immunodeficiency virus (HIV)
  * alcohol/substance use disorder/stimulant/opioid/other depressant misuse in the past year
  * major mental health condition (e.g., psychosis, suicidal ideations, major depressive disorder) that interferes with their ability to accurately report symptoms
  * hospitalized or undergoing invasive procedures in the past 12 months due to exacerbations of any chronic conditions (such as diabetes, coronary artery disease, hypertension, or emphysema)
  * elevated liver enzymes (2.5 times upper limit of normal) at baseline visit
  * estimated glomerular filtration rate less than 60 ml/min/1.73 sqm at baseline visit
  * hemoglobin less than 10 g/L at baseline visit
  * evidence of poorly controlled chronic conditions listed above, or others that may mimic GWI as per the PI, either by self-report, Veterans Health Administration (VHA) electronic health record information review, laboratory testing or physical examination
* Changes in medications for chronic conditions in the 3 months preceding enrollment (based on self-report)
* Suicidal ideation based on their responses on the Columbia Suicide Risk Inventory
* Prescribed or taking Montelukast in the past 6 months for any reason
* Taking 2 or more medications with moderate interactions with Montelukast
* Pregnancy or intention to become pregnant
* Active homicidal ideation
* COVID-19 illness (confirmed or suspected) without recovery to pre-COVID health status