Patient description: The patient is a 16-year-old girl recently diagnosed with myasthenia gravis, class IIa. She complains of diplopia and weakness affecting in her upper extremities. She had a positive anti-AChR antibody test, and her single fiber electromyography (SFEMG) was positive. She is on acetylcholinesterase inhibitor treatment combined with immunosuppressants. But she still has some symptoms. She does not smoke or use illicit drugs. She is not sexually active, and her menses are regular. Her physical exam and lab studies are not remarkable for any other abnormalities. BP: 110/75 Hgb: 11 g/dl WBC: 8000 /mm3 Plt: 300000 /ml Creatinine: 0.5 mg/dl BUN: 10 mg/dl Beta hcg: negative for pregnancy

Clinical trial eligibility criteria: eligible ages (years): 55.0-85.0,  Alzheimer's Disease Dementia Ages ≥55 and ≤85 years Informed consent form (ICF) signed by the subject or legally acceptable representative before any study-specific procedures for the subject are performed and an ICF signed by the support person/caregiver before any study-specific procedures for the support person/caregiver are performed Clinical diagnosis of dementia due to probable AD consistent with established by a workgroup of the National Institute on Aging and the Alzheimer's Disease Association Clinical decline within 12 months before screening and onset of symptoms at least 12 months or longer before screening, which may any documented cognition, functional, or other objective assessment or the clinical judgment of the investigator or the subject's referring physician that the subject has experienced a clinical decline within the last 12 months Magnetic resonance imaging (MRI) or computed tomography (CT) scan performed within 12 months before screening, with findings consistent with the diagnosis of dementia due to AD without any other clinically significant comorbid pathologies. If an MRI or CT scan is unavailable or occurred greater than 12 months before screening, this assessment should be completed and the findings confirmed before the subject enters the run-in period (Day -14) (copy of the report will be available at the study site) Mini-Mental State Examination (MMSE) score ≥14 and ≤24 at screening and confirmed on Day 1 prior to randomization (fluctuations of ±2 points are acceptable on Day 1/baseline) Clinical Dementia Rating Global score (CDR-GS) ≥1 (at least mild dementia) at screening and confirmed on Day 1 prior to randomization Modified Hachinski Ischemic Scale (mHIS) score ≤4 at screening Fertile, sexually active subjects (men and women) must use an effective method of contraception during the study. Female subjects and the female partner of male subjects must be surgically sterile (hysterectomy or bilateral tubal ligation), postmenopausal for at least 1-year, or willing to practice adequate methods of contraception if of childbearing potential (defined as consistent use of combined effective methods of contraception [including at least 1 barrier method]) Reliable and capable support person/caregiver, who if not living in the same household, interacts with the subject approximately 4 times per week and will be available to attend clinic visits in person when possible  Exposure to an experimental drug, experimental biologic or experimental medical device within 2 months (60 days) before screening Prior participation in an amyloid vaccination clinical study at any time in the past or completion of a passive amyloid vaccination study within 6 months before screening Inability to swallow a tablet In the judgment of the investigator, inability of the subject or the support person/caregiver to complete a 26-week study Inability to be ≥75% compliant with single-blind study drug Inability to adequately cooperate or complete the cognitive testing procedures or any study assessment Residence in a skilled nursing facility Untreated vitamin B12 or folate deficiency (if treated, must be stably treated for at least 6 months before screening) Clinically significant (in the judgment of the investigator) abnormal serum electrolytes (sodium, potassium, magnesium) after repeat testing Clinically significant untreated hypothyroidism (if treated, thyroid-stimulating hormone level and thyroid supplementation dose must be stable for at least 6 months before screening)