Inclusion Criteria:
- Male and female subjects 55-80 (inclusive)
- Subjects in good health
At screening:
- oral body temperature between 35-37.5C
- systolic blood pressure: 90-140 mm Hg
- diastolic blood pressure: 50-90 mm Hg
- pulse rate: 40-90 bpm
- Female subjects of child bearing potential must have been using a double-barrier local contraception
- Postmenopausal women must have had no menstrual bleeding
- Subjects must have weighed at least 50 kg
- All subjects must provide informed consent
- All subjects must have been able to communicate well with investigator
Specific to Major depression disorder (MDD)
Patients had to show following level of symptomatology:
- HAM-D (17-item scale) > 16
- CGI > 4 (moderately ill)
Exclusion Criteria:
Specific criteria for healthy volunteers:
- Presence and/or history of clinically significant major neurological or psychiatric disorder
Specific criteria for MDD patients:
- Presence and/or history of a clinically significant major neurological or psychiatric disorder other than MDD or generalized anxiety disorder
- Axis I co-morbidity was excluded except anxiety spectrum disorders
Criteria for both:
- Smokers
- Pregnancy
- Subjects with history of or symptoms/complaints consistent with mild cognitive impairment
- Use of any psychotropic prescription drugs
- Coffee consumers more than 6 cups/day
- Participation in any clinical investigation
- Donation or loss of 400 mL or more of blood
- Significant illness within 2 weeks prior to dosing
- A known hypersensitivity to study drug
- MRI scan that showed evidence of stroke
- Any surgical or medical condition which might have significantly altered distribution
- Clinical evidence of any abnormal lab value
- History of immunodeficiency disease
- Positive Hepatitis B surface antigen
- Presence of contraindications to PET scan investigations- Presence of contraindications to MRI investigations
- Evidence from an Allen test of incomplete communication
- History of drug or alcohol abuse
- Current use of anticonvulsant
- Significant radiation exposure
Other protocol-defined inclusion/exclusion criteria may apply.