Behavioral data from a previous study were stratified by age (< 40 or > 40 years) and duration of hospitalization (< 10 or > 10 years) and examined for dose-response relationships at the 12th week of treatment with either placebo or 150, 300, or 600 mg chlorpromazine per day.
It was found that the shorter hospitalized patients (< 10 years) and to a lesser extent, the younger patients (< 40 years) as well, responded better to the higher dose (600 mg/day) whereas the longer hospitalized patients (> 10 years) and older patients ( ≥ 40 years) achieved no improvement in response beyond 300 mg/day.
L. Clark M, Ramsey HR, Rahhal DK, Serafetinides EA, Wood FD, Costiloe JP. Chlorpromazine in Chronic SchizophreniaThe Effect of Age and Hospitalization on Behavioral Dose-Response Relationships. Arch Gen Psychiatry. 1972;27(4):479-483. doi:10.1001/archpsyc.1972.01750280047009