The FDA has approved several new drugs aimed at treating early-stage Alzheimer’s disease and other dementias, but these medications come with **known serious and sometimes deadly side effects**. The most prominent among these drugs are anti-amyloid therapies such as **lecanemab (Leqembi)** and **donanemab (Kisunla)**, which target amyloid plaques in the brain believed to contribute to Alzheimer’s progression. While these drugs have shown some ability to slow cognitive decline, they also carry risks that have raised significant concerns.
One of the most serious side effects associated with these drugs is a condition called **amyloid-related imaging abnormalities (ARIA)**. ARIA can manifest as brain swelling (edema) or small brain hemorrhages (bleeding), which may be detected through MRI scans. Although many patients with ARIA do not experience symptoms, when symptoms do occur, they can include headache, confusion, dizziness, vision changes, nausea, weakness, seizures, and even stroke-like events. In some cases, ARIA has led to fatal outcomes. For example, clinical trials of donanemab reported a slightly higher mortality rate among treated patients compared to placebo, with some deaths attributed directly to ARIA complications.
The frequency of ARIA varies between drugs and studies but is notably higher in patients receiving these anti-amyloid treatments compared to placebo groups. For instance, in clinical trials, about 17% of patients on lecanemab experienced brain swelling or hemorrhages, compared to 9% in placebo groups. Donanemab trials showed even higher rates of brain abnormalities, with up to 30% of participants affected and several deaths linked to the drug. Because of these risks, the FDA now recommends **regular and earlier MRI monitoring** before and during treatment to detect ARIA early and manage it by pausing or stopping the medication if necessary.
Besides ARIA, these drugs can cause other side effects such as infusion-related reactions, which may include fever, chills, nausea, vomiting, blood pressure changes, and oxygen desaturation. These reactions can be serious and require careful management during treatment infusions.
Other dementia drugs, like **donepezil**, which has been used for many years, also have a range of side effects, some of which can be severe. These include dizziness, muscle cramps, nausea, irregular heartbeat, seizures, and in rare cases, coma. While donepezil and similar cholinesterase inhibitors do not carry the same risks of brain swelling or bleeding as anti-amyloid drugs, their side effects can still be dangerous, especially in older or frail patients.
The approval of these new dementia drugs by the FDA has sparked debate. On one hand, they represent a hopeful advance in treating a devastating disease with few effective options. On the other hand, the **potentially deadly side effects and high costs**—with annual treatment expenses often exceeding $25,000 plus additional costs fo
