The dopaminergic agonist Neupro appeared to improve frontal cognitive functions and activities of daily living among patients with mild to moderate Alzheimer’s disease, according to study results published in JAMA Network Open.
“Some early attempts have been carried out using dopaminergic drugs, such as L-dopa or selegiline, in samples of patients with Alzheimer’s disease at different stages of the disease, with some controversial results,” Giacomo Koch, MD, PhD, of the department of behavioral and clinical neurology at Santa Lucia Foundation Scientific Institute for Research, Hospitalization and Healthcare in Rome, and colleagues wrote. “More recently, experimental studies in animal models of Alzheimer’s disease showed that dopaminergic agonists may reduce amyloid deposition and improve memory and that the degeneration of dopaminergic neurons in the ventral tegmental area contributes to memory deficits. It has also been shown that in the early stages of Alzheimer’s disease, dopaminergic agonists improve cholinergic transmission and cortical plasticity likely by acting on the dopaminergic projections over the frontal cortex.”
This prior evidence suggested novel implications for therapies based on dopaminergic stimulation among patients with mild to moderate Alzheimer’s disease, according to the investigators. Thus, they sought to determine whether dopaminergic agonist therapy would affect cognitive functions among this patient population.
In the current phase 2, monocentric, randomized, double-blind, placebo-controlled trial conducted in Italy and funded by the Alzheimer’s Drug Discovery Foundation, Koch and colleagues enrolled 94 patients (mean age, 73.9 years) with mild to moderate Alzheimer’s disease between September 2017 and December 2018. The intervention comprised use of a Neupro (rotigotine, UCB) 2 mg transdermal patch for 1 week, followed by a 4 mg patch for 23 weeks among 47 patients or a placebo transdermal patch for 24 weeks among 47 patients. Change from baseline on the Alzheimer’s Disease Assessment Scale-Cognitive Subscale served as the primary end point. Secondary end points included changes in Frontal Assessment Battery, Alzheimer’s Disease Cooperative Study-Activities of Daily Living and Neuropsychiatric Inventory scores. The researchers used transcranial magnetic stimulation combined with electroencephalography to evaluate prefrontal cortex activity.
A total of 78 patients completed the study. Results showed rotigotine compared with placebo had no significant effect on the primary end point, with an estimated mean change in Alzheimer’s Disease Assessment Scale-Cognitive Subscale score of 2.92 (95% CI, 2.51-3.33) among the rotigotine group and 2.66 (95% CI, 2.31-3.01) among the placebo group. The researchers reported significant estimated mean changes for the secondary outcomes between groups for Alzheimer Disease Cooperative Study-Activities of Daily Living score, which was 3.32 (95% CI, 4.02 to 2.62) among the rotigotine group and 7.24 (95% CI, 7.84 to 6.64) among the placebo group. Frontal Assessment Battery score was 0.48 (95% CI, 0.31-0.65) among the rotigotine group and 0.66 (95% CI, 0.80 to 0.52) among the placebo group. Koch and colleagues observed no longitudinal change in Neuropsychiatric Inventory scores for either group. Neurophysiological analysis of electroencephalography results revealed increased prefrontal cortical activity among the rotigotine group but not the placebo group. Patients in the rotigotine group were more likely to experience adverse events than the placebo group, and 11 patients dropped out compared with five, respectively.
“This study provides novel evidence that drugs acting on the dopaminergic system may be helpful to improve cognitive functions related to the frontal lobe activity,” Koch told Healio Psychiatry. “We hope that this research will expand Alzheimer’s disease therapy to drugs acting on different neurotransmission systems, such as the dopaminergic one, in addition to the cholinergic drugs.”