For ALL arms:
Inclusion Criteria:
- Currently resides in The Villages community
- Age 50-years and above.
- Able to speak, read and understand English
- Willingness to participate and able to give informed consent.
- If corrected vision: only Glasses should be used during the study testing
Exclusion Criteria:
- Currently with lice or open wounds on scalp.
- Any CNS neurologic disorder
- Significant sensory deficits.
- Use of a hearing aid that occupies the ear canal
- Any neuropsychological disorders
- History of special education
- Substance abuse in the last 3 months
- History of any clinically significant brain trauma as determined by the investigator.
- Clinically diagnosed with a concussion in the past year.
For Arm 1 Healthy
Inclusion Criteria:
- BDI score <14
- Subjects Not meeting diagnostic criteria for MDD per the DSM IV-TR,
- MMSE score ≥25
Exclusion Criteria:
- Any chronic disease or condition which affects the nervous system as determined by clinical neurological evaluation, medical history or PI discretion.
- Any psychiatric disorder,
- History of any medication affecting CNS within the last 3 months
For Arm 2 Early Alzheimer's Disease
Inclusion Criteria:
- BDI score <14
- Subjects Not meeting diagnostic criteria for MDD per the DSM IV-TR, as determined by clinical evaluation by a research clinician and the Mini International Neuropsychiatric Interview (MINI).
- MMSE score <24
- MoCA<20
- Presence of an early and significant episodic memory impairment
Exclusion Criteria:
- Any chronic disease or condition other than current pathology
- Any other psychiatric disorder
- CNS medications within the short period of time prior to the EEG testing which are not in a medically stable treatment phase.
For Arm 3 Depression
Inclusion Criteria:
- BDI score >14
- Subjects meeting full diagnostic criteria for MDD without psychotic features per the DSM IV-TR
- HAM-D 17-item: Total score of 16 or higher at visit 1.
Exclusion Criteria:
- Any chronic disease or condition other than current pathology
- Any psychiatric disorder other than Depression
- CNS medications within the short period of time prior to the EEG testing which are not in a medically stable treatment phase.
For Arm 4 Mild Cognitive Impairment
Inclusion Criteria:
- BDI score <14
- Subjects Not meeting diagnostic criteria for MDD per the DSM IV-TR
- MMSE scores according to Number of years of Education:
MMSE score Years of Education 17-18 ≤6 20-21 7-8 23-24 ≥10
-20<MoCA score >26
Exclusion Criteria:
- Any chronic disease or condition other than current pathology
- Any other psychiatric disorder
- CNS medications within the short period of time prior to the EEG testing which are not in a medically stable treatment phase.