Lowering Antipsychotic Dose Safe For Older Schizophrenia Patients

the Psychiatry Advisor take:

Clinicians who treat older patients with schizophrenia can safely reduce the antipsychotic dose in this population to minimize side effects without sacrificing the effectiveness of the medication.

Ariel Graff-Guerrero, MD, PhD, with the Center for Addiction and Mental Health in Toronto, and colleagues conducted a trial of 35 patients who were at least 50 years old and had late-life schizophrenia (LLS). All participants were taking either risperidone (Risperdal) or olanzapine (Zyprexa) for between 6 and 12 months.

The antipsychotic dosage was incrementally reduced up to 40% of a patient's baseline dose. Assessment and brain scans were conducted two weeks after the final lowered dose was achieved. Participants were then followed for between 3 and 6 months.

The researchers examined the impact of reducing the dose of the antipscychotic on dopamine D_2/3 receptor (D_2/3R) occupancies using PET scans. Other studies have indicated that occupancy between 65% and 80% is effective in younger patients, as going above 80% occupancy is associated with extrapyramidial effects.

In the current study, the mean baseline striatal D_2/3R occupancy was 70%, but declined to a mean of 64% after the antipsychotic dose was reduced by an average of around 35%. In the 29 participants who remained stable during the follow-up period, mean D_2/3R occupancy was 66%, though the lowest occupancy observed was 50%.

“Antipsychotic dose reduction is feasible in patients with stable LLS, decreasing adverse effects and improving illness severity measures,” the researchers concluded. “The results of the present study suggest a lower therapeutic window of D_2/3R occupancy in patients with LLS (50%-60%) than previously reported in younger patients (65%-80%).”