Deep Brain Stimulation in Treatment Resistant Schizophrenia

The first phase of the study will consist of implanting electrodes. Recruited patients will be random to 2 targets: (1) medial prefrontal cortex (mPFC); (2) nucleus accumbens (NAcc). Continuous stimulation will be applied until the patients stabilise clinically. This period is anticipated between 6 and 9 months.

After this stage, the next phase will consist of the crossover study. Those patients who respond to DBS will be randomly distributed in two groups, for a period of 3 months: on stimulation group and off stimulation group. Patients will then be crossed over to the other group for a further 3 months.

Weekly visits during first month after, and fortnightly visits will be made during the entire study to evaluate treatment efficacy and patient tolerance.

Patients who complete the study and respond to treatment with DBS will be provided continuing with treatment, and keeping control visits to assess the long-term effectiveness.

Inclusion criteria

• Male or female aged between 18 and 55 years.
• DSM IV-TR diagnosis of schizophrenia for at least 3 years prior to the screening visit.
• Determined to be treatment-resistant as demonstrated by:

• Persistence of positive symptoms which have not responded to appropriate treatments for at least 2 years.
• Inadequate response from adequate trials of two different classes of antipsychotic drugs (not including clozapine), at least 8 weeks.
• Inadequate response from adequate trial of clozapine, at least 3 months, or unable to tolerate clozapine because of intolerable side effects.
• ECT is contraindicated or have failed to produce a maintained response.
• Persistence of positive symptoms defined as i) requiring a score of 4 (mild) or more on at least 2 of the next PANSS items: delusions, hallucinatory behavior, suspiciousness and unusual thought content; or as ii) requiring a score of 6 (severe) or more on at least 1 of the above PANSS items.
• Current CGI score 6 or more
• Stable antipsychotic treatment for last 2 months.
• Women of childbearing age using medically approved contraceptive methods.
• Adequate familiar or social support during all study procedures.

Exclusion criteria

• MRI (Magnetic Resonance Imaging) contraindication to stimulation or contraindications for MRI
• History of epilepsy or clozapine-induced seizures, where use of anticonvulsants was needed
• Current suicidal ideation, plan or intent for self-harm during last 2 months.
• Evidence of global cognitive impairment.
• Current acute, serious or unstable illnesses.
• History of substance abuse (other than tobacco or caffeine).
• Comorbid axis I or II DSM IV-TR disorders.
• Female patients who are pregnant or breastfeeding.