Safety and Efficacy Study for Cognitive Deficits in Adult Subjects With Schizophrenia

This is a Phase 2 study designed to evaluate the efficacy and safety of ABT-126 in
approximately 210 adults with schizophrenia. Subjects will be randomized to one of three
treatment groups (ABT-126 Dose 1, ABT-126 Dose 2 or placebo) for a 12-week Treatment Period.
The purpose of this research study is to find out whether ABT-126 compared to placebo can
improve cognition and what side effects ABT-126 may cause. Cognition is the way a person
thinks, and it includes abilities like paying attention, focusing, remembering things, and
solving problems. Acronyms listed in the Outcomes and/or Eligibility sections for this study
are defined below: • MCCB: Measurement and Treatment Research to Improve Cognition in
Schizophrenia (MATRICS) Consensus Cognitive Battery • UPSA-2: University of California at San
Diego (UCSD) Performance-Based Skills Assessment-2 • CANTAB: Cambridge Neuropsychological
Test Automated Battery • PANSS: Positive and Negative Syndrome Scale • NSA-16: Negative
Symptom Assessment-16 • CGI-S: Clinical Global Impression - Severity

Inclusion Criteria

- Has current DSM-IV-TR diagnosis of schizophrenia confirmed by the Mini-International
Neuropsychiatric Interview.

- Is clinically stable while receiving antipsychotic therapy with one or two atypical
antipsychotic medications: lack of hospitalizations from 4 months of Initial Screening
Visit; taking same antipsychotic medication(s) for at least 8 weeks prior to the Day
-1 visit; core positive symptoms of PANSS no worse than moderate in severity
throughout Screening Period of at least 4 weeks.

- Has been diagnosed with or treated for schizophrenia for at least 2 years prior to
Initial Screening Visit.

- Has had continuity in psychiatric care (e.g., mental health system, clinic or
physician) for at least 6 months prior to Initial Screening Visit.

- Has an identified responsible contact person (e.g., family member, social worker, case
worker, or nurse) that can provide support to the subject and ensure compliance with
protocol requirements.

Exclusion Criteria

- Has valid current or past diagnosis of schizoaffective disorder, bipolar disorder,
manic episode, dementia, posttraumatic stress disorder, obsessive compulsive disorder,
or a current major depressive episode.

- Has history of substance abuse (excluding nicotine or tobacco products) or alcohol
abuse within 6 months prior to Screening Visit; has a substance dependence disorder
(excluding nicotine or tobacco products) that has not been remitted for at least 1
year prior to Initial Screening Visit.

- Is taking any medication for extrapyramidal symptoms at any time from the Initial
Screening Visit until the Day -1 Visit.

- Is taking any antidepressant that is excluded, including tricyclic antidepressants and
monoamine oxidase inhibitors, at any time from 8 weeks prior to the Day -1 Visit.

- Has significant suicidal ideation at Initial Screening Visit.

- Has had a suicide attempt within 1 year prior to the Day -1 Visit.

- Has participated in another trial utilizing the MATRICS Consensus Cognitive Battery
(MCCB) or UCSD Performance-Based Skills Assessment (UPSA) (any version) within 6
months prior to Initial Screening Visit.

- Is currently enrolled in any form of cognitive remediation training.