Tau Biomarkers in Late-onset Psychosis (LOP)

Inclusion Criteria:

1. Male or female, aged 65-85 years.
2. Diagnosis of late-onset non-affective primary psychotic disorder consistent witheither very late-onset schizophrenia-like psychosis (VLOSP, International Late-OnsetSchizophrenia Group consensus criteria, Howard et al., 2000) or delusional disorder (DSM-5 criteria)
3. Caregiver available to provide collateral history and participation in informant-basedratings (NPI,CDR)
4. Clinical Dementia Rating (CDR) score of 0 or 0.5.
5. Mini-Mental State Examination (MMSE) score ≥ 24 and at the screening visit.
6. Normal memory function (to rule-out mild cognitive impairment, MCI) documented byscoring within 1.5 SD range in education adjusted norms of the Logical Memory IIsubscale
7. Ability to hear 500, 1000 and 1500 Hz bilaterally on a hearing evaluation (hearingaids permitted).

Exclusion Criteria:

1. Participants with affective and psychotic disorders including bipolar disorder,schizoaffective disorder, active major depression; insulin dependent type 2 diabetes;a history of CVD; a history of epilepsy; a history of TBI with greater than 15 minutesof loss of consciousness; a movement disorder including Parkinson's disease; stroke;autoimmune disease affecting the CNS; substance abuse disorder; or activedelirium/encephalopathy.
2. Evidence of a clinically relevant neurological disorder
3. Modified Hachinski ischemia score of more than 4.
4. History of alcoholism or drug dependency/abuse within the last 5 years beforescreening.
5. Presence of metal implants such as pacemakers, ear implants, internal bullet fragmentsor shrapnel.
6. Inability to lie flat for 1 hour approximately.
7. Hearing impairment as evidenced by the inability to hear 500, 1000 and 1500 Hzbilaterally on a hearing evaluation. Subjects with hearing aids will be allowed toparticipate if they meet minimum hearing requirements.