Internet-based Conversational Engagement Clinical Trial

**Due to COVID-19 pandemic and resultant research hiatus and the subsequent changes in assessment modality from in-person to telephone (T-COG) assessments, M12 (Months 12) assessments are conducted only among those who completed M12 assessments before March, 18, 2020.

Inclusion criteria

• Age 75 or older
• Consent to MRI (if physically able to receive one)
• Socially isolated, defined by at least one of the following:

i. Score ≤12 on the 6-item Lubben Social Network Scale (LSNS-6), ii. Engages in conversations lasting 30 minutes or longer no more than twice per week, per subject self-report iii. Answers "Often" to at least one question on the Hughes et al. Three-Item Loneliness Scale

• Adequate vision to use study technology and complete all neuropsychological tests throughout the study, defined by the following two criteria:

i. See well enough to complete the MoCA ii. See well enough to read a newspaper, wearing glasses if needed but not using a magnifying glass

• Adequate hearing to use study technology and complete all neuropsychological tests throughout the study, defined as i. Able to hear well enough to complete the telephone screening ii. Able to hear well enough to complete the MoCA
• Sufficient ability to understand English in order to complete protocol-required testing
• Normal cognition or mild cognitive impairment (MCI), as assessed by the trial neuropsychologist
• Sufficiently able to comply with protocol assessments and procedures, in the opinion of the investigator

Exclusion criteria

• Identified as having dementia based on either of the following criteria:

i. Self-reported diseases associated with dementia, such as Alzheimer's disease, vascular dementia, Lewy body dementia, front temporal dementia, normal pressure hydrocephalus, or Parkinson's disease ii. Diagnosis of dementia by trial neuropsychologist

• Anticipating major change in living arrangement within the upcoming year
• Severely depressed, operationally defined as a 15-item GDS score > 7
• Significant disease of the central nervous system, such as brain tumor, seizure disorder, subdural hematoma, or significant stroke, per subject report
• Current (within 2 years of screening) alcohol or substance abuse
• Unstable or significantly symptomatic psychiatric disorder, such as major depression, schizophrenia, posttraumatic stress disorder, or bipolar disorder
• Unstable or significantly symptomatic cardiovascular disease, such as coronary artery disease with frequent angina, or congestive heart failure with shortness of breath at rest
• Unstable insulin-dependent diabetes mellitus, defined as meeting any of the following criteria:

i. Received a diagnosis of Type 1 Diabetes ii. Started taking insulin within 3 months of the screening visit iii. Been hospitalized for hypoglycemia within one year of screening

• Active systemic cancer within 5 years of the screening visit (Gleason Grade < 3 prostate cancer and non-metastatic skin cancers are acceptable)
• Surgery that required full sedation with intubation within 6 months of screening (sedation for minor procedures is acceptable)
• More than one overnight hospital stay within 3 months of the screening visit
• Any other condition that, in the opinion of the investigator, is severe enough to cause study participation to have a negative impact on participant or study team rights or wellbeing.