A Study With [18F]MNI-1054 to Determine Lysine -Specific Demethylase 1A (LSD1) Brain Enzyme Occupancy of TAK-418 After Single-Dose Oral Administration in Healthy Participants

The purpose of this study is to determine brain LSD1 enzyme occupancy and the relationship of occupancy to TAK-418 dose and plasma exposure after single oral dosing of TAK-418 in healthy participants using \[18F\]MNI-1054 positron emission tomography (PET) imaging.

The drug being tested in this study is called TAK-418. TAK-418 is being tested to determine the relationship between brain LSD1 enzyme occupancy and TAK-418 plasma concentration. This study will utilize the PET radiotracer \[18F\]MNI-1054 to evaluate the brain LSD1 enzyme occupancy of TAK-418 after single dose oral administration in healthy adult participants.

The study will enroll approximately 16 participants. The TAK-418 starting dose is 1.5 mg, given on Day 1. Each participant will receive one dose of TAK-418 and up to 3 dynamic \[18F\]MNI-1054 PET scans to assess enzyme occupancy on baseline, Day 1 and Day 2 or 3 post-TAK-418 dosing.

This single center trial will be conducted in the United States. The overall time to participate in this study is 62 days. Participants will be followed up on Day 14 for follow-up safety assessments.

Eligibility Criteria:
Inclusion Criteria:

1. The participant must have a body mass index (BMI) greater than or equal to (\>=) 18.5 and less than or equal to (\<=) 30.0 kilogram per square meter (kg/m\^2) at the screening visit.
2. The participant must be a current nonsmoker at screening as demonstrated by negative cotinine test.
3. The participant has adequate circulation to both hands for safe placement of arterial lines (as determined by Allen's test).

Exclusion Criteria:

1. Has a known hypersensitivity to any component of the formulation of TAK-418 or related compounds, including \[18F\]MNI-1054.
2. The participant has a positive alcohol or drug screen.
3. The participant has a history of alcohol consumption exceeding 2 standard drinks per day on average (1 glass is approximately equivalent to the following: beer \[354 milliliter (mL)/12 ounce (oz)\], wine \[118 mL/4 oz\], or distilled spirits \[29.5 mL/1 oz\] per day).
4. The participant consumes excessive amounts, defined as greater than 6 servings (1 serving is approximately equivalent to 120 mg of caffeine) of coffee, tea, cola, energy drinks, or other caffeinated beverages per day.
5. The participant has a substance abuse disorder.
6. The participant cannot tolerate venipuncture or has poor venous access that would cause difficulty in collecting blood samples.
7. The participant has contraindications to undergoing magnetic resonance imaging (MRI) examination including but not limited to implants, such as implanted cardiac pacemakers or defibrillators, insulin pumps, cochlear implants, metallic ocular foreign body, implanted neural stimulators, central nervous system aneurysm clips, and other medical implants that have not been certified for MRI, or history of claustrophobia in MRI.
8. The participant has clinically significant abnormal findings on brain MRI scan that in the opinion of the investigator may interfere with the interpretation of the PET imaging.
9. The participant has experienced an acute illness within 10 days before the screening visit.
10. The participant has a risk of suicide according to the investigator's clinical judgement per the Columbia-Suicide Severity Rating Scale at screening or has made a suicide attempt in the 12 months before screening.
11. The participant has luteinizing hormone, follicle stimulating hormone (FSH), or estradiol levels that are clinically abnormal.
12. The participant has existing skin rashes that can be diagnosed as dermatitis.