Inclusion Criteria:

• Age 60 Years or older
• BP Disorder-I or II: Depressive episode (DSM -IV-TR; SCID-I/P)
• HAM-D score > 18 (GRID-HAM-D 24-item version)
• Availability of an Informant is encouraged but not required for study participation

Exclusion Criteria:

• Chronic psychotic conditions, ie. schizophrenia, schizoaffective disorder, delusional disorder
• Contraindication to lamotrigine (Physician interview, medical assessment)
• Documented history of intolerance to lamotrigine
• Patients who have previously failed to respond to at least 12 weeks of treatment with lamotrigine
• Active substance dependence (SCID-I/P) or substance-related safety issues or PI concerns
• Mood Disorder Due to a General Medical Condition or Treatment (Physician interview)
• Rapid cycling (Physician interview): As defined in DSM-IV: At least 4 episodes of mood disturbance in the previous 12 months that meet criteria for a Major Depressive, Manic, Mixed or Hypomanic Episode. Episodes are distinguished either by partial or full remission for at least 2 months or by a switch to an episode of opposite polarity
• Dementia (by DSM-IV or brain degenerative diseases; Physician interview);
• Inability to communicate in English (i.e., interview cannot be conducted without an interpreter; subject largely unable to understand questions and cannot respond in English)
• Clinically significant sensory impairment (i.e., cannot see well enough to read consent or visually-presented material; cannot hear well enough to cooperate with interview; Physician interview)
• Recent history of cardiovascular, peripheral vascular events or stroke
• High risk for suicide (e.g., active SI or current intent or plan)
• Inpatient status