This study will assess the adverse events, tolerability, and how oral ascending doses of ABBV-1042 moves through the body of healthy adult participants.

Inclusion Criteria:

• BMI is ≥ 18.0 to ≤ 32.0 kg/m2 after rounding to the tenths decimal at Screening. BMI is calculated as weight in kg divided by the square of height measured in meters.
• Body weight ˃ 45 kg at the time of screening and upon initial confinement.
• A condition of general good health, based upon the results of a medical history, physical examination, vital signs, laboratory profile and a 12-lead ECG

Exclusion Criteria:

• History of suicidal ideation within one year prior to study treatment administration and/or history of suicidal behavior or non-suicidal self-injury within two years prior to study treatment administration as evidenced by any "yes" answer to questions on the Columbia-Suicide Severity Rating Scale (C-SSRS) at the screening visit or upon initial confinement.
• Current or past history of significant cardiovascular, pulmonary, gastrointestinal, renal, hepatic, metabolic, genitourinary, endocrine (including diabetes mellitus, thyroid disorders), malignancy, hematological, immunological, neurological, or psychiatric disease that, , in the opinion of the investigator, could compromise either participant safety or the results of the trial.