Serotonin Transporter Density in Late-life Depression With and Without Dementia

1. Patients may be enrolled in the AD depressive group if they:

   • Are males or females at least 50 years of age;
   • Fulfilled the DSM-IV criteria for Major depressive disorder (APA, 1994) by MINI interview.
   • Meet the NINCDS/ADRDA(National institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association) criteria for probable AD
   • A Mini Mental State Examination (MMSE) score at screening between 10 and 24 inclusive;
   • Give informed consent. If the patient is incapable of giving informed consent, the caregiver may consent on behalf of the patient (the patient must still confirm assent).

2. Patients may be enrolled in the cognitively depressive group if they:

   • Are males or females at least 50 years of age;
   • Fulfilled the DSM-IV criteria for Major depressive disorder (APA, 1994) by MINI interview.
   • Memory function above the lower normal limits (i.e. 1.5 SD above the mean) on tests for episodic memory.
   • Clinical Dementia Rating = 0. Memory Box score must be 0.
   • Cognitively normal, based on an absence of significant impairment in cognitive functions or ADL.
   • A MMSE score at screening > 24 for those with education level of 6 years or above and > 17 for those are illiterate;
   • Give informed consent.

Exclusion Criteria:

• Pregnant or becoming pregnant during the study (as documented by pregnancy testing at screening or at any date during the study according to the PI discretion) or current breast feeding.
• Conditions affecting brain structure or function (e.g., stroke, diabetes, head trauma, depression) or use of cognitively
• Substance abuse.
• Alcohol dependence