∙ Part 1: Participants are eligible to be included in the study only if all of the following criteria apply

• Provision of signed and dated, written informed consent prior to any study specific procedures.

• Healthy male and/or female (of nonchildbearing potential) participants aged 18 to 65 years, inclusive.

• A body mass index (BMI) between 18 to 30 kg/m2, inclusive.

• Females must have a negative pregnancy test at the Screening Visit and on admission to the study center, must not be lactating and must be of nonchildbearing potential, confirmed at the Screening Visit by fulfilling 1 of the following criteria:

‣ Postmenopausal defined as amenorrhea for at least 12 months following cessation of all exogenous hormonal treatments and with follicle stimulating hormone levels in the laboratory defined postmenopausal range.

⁃ Documentation of irreversible surgical sterilization by hysterectomy, bilateral oophorectomy or bilateral salpingectomy but not tubal ligation.

• Male participants should be willing to use double barrier contraception ie., condoms and spermicide, from the day of dosing until at least 3 months after dosing with the investigational product.

• Male participant must not donate sperm from the day of dosing until at least 3 months after dosing with the investigational product.

• Medically healthy with clinically insignificant screening results (eg, laboratory profiles, medical history, electrocardiograms \[ECGs\], and physical examination) as judged by the Principal Investigator.

• Has to agree to abstain from alcohol intake 48 hours before administration of the study intervention and through the follow-up visit.

• Able to be compliant with the protocol and attend all scheduled visits.

∙ Part 2: Participants are eligible to be included in the study only if all of the following criteria apply

• Age between 50 and 80 years.

• Participants with MCI due to AD:

• i. Meet the National Institute on Aging - Alzheimer's Association (NIA-AA)6 core for MCI due to AD-intermediate likelihood.

• ii. Have a global clinical dementia rating (CDR) score of 0.5 and a CDR Memory Box score of 0.5 or greater at Screening and Baseline.

• iii. Report a history of subjective memory decline with gradual onset and slow progression over the last 1 year before Screening; must be corroborated by an informant.

• Participants with Mild AD dementia:

• iv. Meet the NIA-AA6 core for probable AD dementia. v. Have a global CDR score of 0.5 to 1.0 and a CDR Memory Box score of 0.5 or greater at Screening and Baseline.

• Body weight of ≥50 kilograms and BMI between 18 and 35 kg/m2, inclusive.

• Mini-Mental State Examination (MMSE) score of greater than or equal to 21 and less than or equal to 27 at screening.

• Must have a positive amyloid positron emission tomography (within 12 months prior to screening) or CSF Abeta (42/40) ratio consistent with AD pathology.

• Stable dose of AD treatment (Cholinesterase inhibitors \[donepezil, rivastigmine, galantamine\] and N-methyl-D-aspartate receptor antagonist \[memantine\]) 3 months before screening visit or being untreated.

• Written informed consent must be obtained by participant or surrogate consenter (legally authorized representative).

• Adequate visual and auditory abilities and language skills to allow neuropsychological testing.

• Must be ambulatory.

⁃ Availability of partner/caregiver who spends at least 5 hours per week with the participant and is willing to act as a study partner and to consent for the study.

⁃ Participant on stable doses of all medications for concomitant illnesses according to medical history for at least 30 days prior to Visit 1 if considered relevant by the investigator.

⁃ Sexually active males and female must be using reliable contraception methods or be surgically sterile.