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