A new report seeks to classify the long-term impacts of Alzhiemer’s disease medications that target amyloid beta proteins in the brain.

Clinical trials have shown that such therapies have clinical benefits over 18 months. But clinicians don’t know about the long-term impacts of these medications, the team noted in a report published Monday in Alzheimer’s & Dementia. One of the researchers was from Eli LIlly, the company that makes donanemab (Kisunla), an FDA-approved treatment for the disease.

“To better understand the significance of the novel amyloid beta-targeting therapies, it is crucial to understand treatment effects in the context of the natural history of Alzheimer’s disease,” the authors wrote.

Investigators used results from recent phase 3 trials of Aβ-targeting antibodies and integrated them with an estimate of the long-term disease trajectory. The team evaluated three different long-term efficacy scenarios, ranging from conservative to more optimistic. The team considered differences in trial populations and trial duration, which influenced differences in treatment results, the authors noted. 

In addition donanemab (Kisunla), researchers assessed clinical trials on aducanumab (Aduhelm) and lecanemab (Leqembi).

The conservative scenario suggested that benefits occurred when the patient was on the medication, but the disease progresses naturally if the drug is discontinued. The optimistic scenario extrapolated the time saving observed during the study period compared to the regular course of the disease. In this scenario, patients continued to decline but they deemed it optimistic because it was unlikely that amyloid clearance could result in substantially increasing benefit after the end of the trial.

According to the study’s long-term scenarios, starting the treatments during the early symptomatic stages of Alzheimer’s disease could delay severe dementia in the conservative scenario by 4 to 7 months, by 1.1 to 1.9 years in the intermediate scenario or 2.0 to 4.2 years in the optimistic scenario. 

“If amyloid clearance results in cumulative benefits like the continued and fading slowing scenarios, the most substantial long-term benefits would occur if amyloid beta -targeting treatments were used in the presymptomatic stage of Alzheimer’s disease,” the authors wrote.