Inclusion Criteria:
- Age 45 years or older
- No significant cerebrovascular disease - modified Ischemic Score of < 4
- Adequate visual and auditory acuity to allow neuropsychological testing
- Screening laboratory tests and ECG without significant abnormalities that might interfere with the study
Additional Inclusion Criteria for Controls
- MMSE score between 24 and 30 (unless < 8 years of educational achievement)
- The following medications are allowed if stable for > 1 month: antidepressants (without anticholinergic effects) if not currently depressed and no history of major depression for 2 years; estrogen replacement therapy; thyroid replacement therapy as long as individual is euthyroid; antihypertensives that do not influence cognitive function
Additional Inclusion Criteria for Individuals with Down syndrome
- Family member or caregiver available; caregiver relationship 2 years or longer
- Karyotype DX of trisomy or translocation DS Mosaic form of Down syndrome
- English-speaking
Exclusion Criteria:
- Evidence of neurological or other physical illness that could produce cognitive deterioration; volunteers with a history of TIAs, carotid bruits, or lacunes on MRI scan will be excluded
- Parkinson's Disease
- History of myocardial infarction within the previous year or unstable cardiac disease
- Uncontrolled hypertension (systolic BP > 170 or diastolic BP > 100), history of significant liver disease, clinically significant pulmonary disease, diabetes, or cancer
- Major psychiatric disorders, such as bipolar disorder or schizophrenia
- Medicines that could influence psychometric test results
- Use of any of the following drugs: centrally active beta-blockers, narcotics, clonidine, anti-Parkinsonian medications, benzodiazepines, systemic corticosteroids, medications with significant cholinergic or anticholinergic effects, anti-convulsants, or warfarin
- Current diagnosis or history of alcoholism or drug dependence
- Evidence of untreated depression or untreated anxiety
- Use of any investigational drugs within the previous month or longer, depending on drug half-life
- Contraindication for MRI scan (e.g., metal in body, claustrophobia)
- Diagnosis of possible or probable AD or any other dementia (e.g., vascular, Lewy body, frontotemporal) or MCI
Additional Exclusion Criteria for Individuals with Down syndrome
- Mosaic form of Down syndrome
- History of clinically significant neurological disorder or disease and Psychiatric diagnosis or treatment within 3 months prior to screening