Safety and Target Engagement of Centella Asiatica in Cognitive Impairment

Inclusion criteria:

* Age 60-85, male and female
* Sufficient English language skills to complete all tests
* Sufficient vision and hearing to complete all tests
* No known allergies to Centella asiatica
* Absence of significant depression symptoms (Geriatric Depression Scale-15 score of \< 5).
* Total score of \<2 on the suicidal ideation subscale (measures 3, 7, 11, 12 and 14) of the Geriatric Depression Scale.
* Body Mass Index (BMI) greater than 17 and less than 35 at screening
* General health status that will not interfere with the ability to complete the study
* Willingness to discontinue all botanical dietary supplements for one week prior to and during the study.
* Willingness to undertake multiple MRI scans
* Meet the National Institute of Aging - Alzheimer's Association core clinical criteria for MCI or probable AD dementia with a Clinical Dementia Rating score of 0.5-1 and Mini Mental State Examination score of 20-28 at screening and baseline
* Participants who report a history of participative memory decline with gradual onset and slow progression over the last one year before screening MUST be corroborated by an informant.
* Participants on acetylcholinesterase inhibitor or memantine therapy for AD must be on a stable dose for at least 12 weeks prior to baseline visit.
* Participants must have an identified caregiver/study partner that can accompany participant to all study visits.

Exclusion criteria:

* Current smoking, alcohol, or substance abuse according to DSM-V criteria
* Women who are pregnant, planning to become pregnant, or breastfeeding
* Men who are actively trying to conceive a child or planning to within three months of study completion
* Severe aversion to venipuncture
* Abnormal labs indicating asymptomatic and untreated urinary tract infection
* Cancer within the last five years, with the exception of localized prostate cancer (Gleason Grade \< 3) and non-metastatic skin cancers
* Comorbid conditions such as type I diabetes mellitus, poorly controlled type II diabetes mellitus (HbA1c \> 7%), kidney failure, liver failure, hepatitis, blood disorders, clinical symptomatic orthostatic hypotension, and unstable or significantly symptomatic cardiovascular disease
* Significant disease of the Central Nervous System (CNS) such as brain tumor, seizure disorder, subdural hematoma, cranial arteritis, or clinically significant stroke
* Major depression, schizophrenia, or other major psychiatric disorder defined by DSM-V criteria
* Medications: anti-epileptics, sedatives, amitriptyline, anticoagulants (e.g., warfarin), investigational drugs used within five half-lives of baseline visit, systemic corticosteroids, neuroleptics, anti-Parkinsonian agents, narcotic analgesics, nicotine (tobacco, patches, gum, lozenges, etc.), Cannabis sativa (herb or edibles), beta blockers and anti-depressant medications that have not been at stable dosage for two months (including SSRIs, SNRIs)
* Non-Alzheimer dementia such as vascular dementia, normal pressure hydrocephalus, or Parkinson's disease
* MMSE score of \< 20 or \> 28
* Unwilling to maintain stable dosage of AD medications throughout study duration
* Unwilling to maintain stable dosage of intervention throughout the course of the study
* Contraindications to Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopic Imaging (MRSI) scans (some metal implants, pacemakers, claustrophobia)