Inclusion Criteria:
* Healthy male and female (of non-childbearing potential) participants with suitable veins for cannulation or repeated venipuncture at the Screening Visit.
* All females must have a negative pregnancy test. Females of non-childbearing potential must be confirmed via post-menopausal status or documentation of irreversible surgical sterilization at the Screening Visit.
* Sexually active fertile male participants with partners of childbearing potential must adhere to the contraception methods.
* Have a body mass index between 18 and 32 kg/m2 inclusive and weigh at least 50 kg at Screening.
* For healthy Japanese cohorts (Part A2 and Part B2): healthy male and female participants are to be Japanese (eg, natives of Japan or Japan Americans), defined as having both parents and 4 grandparents who are Japanese. This includes second and third generation participants of Japanese descent whose parents or grandparents are living in a country other than Japan.
* For healthy Chinese cohort (Part A3): healthy male and female Chinese participants for whom both parents and 4 grandparents are Chinese. This includes second and third generation participants of Chinese descent whose parents or grandparents are living in a country other than China.
Exclusion Criteria:
* History of any clinically important disease or disorder which, may either put the participant at risk because of participation in the study, or influence the results or the participant's ability to participate in the study.
* History or presence of gastrointestinal, hepatic, or renal disease or any other condition known to interfere with absorption, distribution, metabolism, or excretion of drugs.
* Any clinically important illness, medical/surgical procedure, or trauma within 4 weeks of the first administration of study intervention.
* Any abnormal laboratory values, vital signs, or any clinically important abnormalities in clinical chemistry, hematology, or urinalysis results.
* Any positive result on Screening for serum hepatitis B and C viruses and human immunodeficiency virus.
* Any clinically important abnormalities in rhythm, conduction, or morphology of the resting 12 lead electrocardiography at Screening and/or admission to the Clinical Unit .
* Known or suspected history of alcohol or drug abuse or excessive intake of alcohol.
* Positive screen for drugs of abuse, or alcohol, or cotinine.
* History of severe allergy/hypersensitivity or ongoing clinically important allergy/hypersensitivity.
* Participants who have previously received AZD3974.
