Biomarkers

Amyloid related imaging abnormalities-hemosiderin (ARIA-H) refers to a form of cerebrovascular alteration observed in Alzheimer's disease (AD) patients, typically linked to anti-amyloid immunotherapies. However, through placebo controlled clinical trials, we understand that ARIA-H can also occur naturally in patients with AD, independent of therapeutic interventions. The purpose of this study is to explore associated risk factors for naturally occurring ARIA-H in patients with AD.

Using placebo arm data from the EXPEDITION 1 randomized control trial, patients were included in the analysis if they had both baseline volumetric/microhemorrhage MRI data and microhemorrhage MRI data throughout the clinical trial. Patients identified with new ARIA-H microhemorrhages at any post-baseline MRI were considered cases. Demographics, comorbidities, medication usage, MMSE, CSF, MRI, and PET scan variables were assessed, and p-values were calculated via Chi-square, Fisher's exact test, or ANOVA for each variable.

Of the total of 460 patients included in the study, 21 (4.2%, 14 female) patients had incident ARIA-H and 439 (95.4%, 245 female) were classified as controls. Statistically significant differences between the cases and controls included untreated hyperlipidemia (Cases: 23.8% vs Controls: 7.1%; p-value: 0.01), diabetes diagnosis (Cases: 0.0% vs Controls: 14.1%; p-value: 0.04), ARIA-H at baseline (Cases: 4.8% vs Controls: 21.4%; p-value: 0.04), and mean CSF t-Tau at baseline (Cases: 976.1 (SD 62.1) vs Controls: 540.3 (SD 270.9); p-value: 0.03). Traditional anti-amyloid immunotherapy ARIA-H risk factors, such as the APOE 4 status and age, did not have a statistically significant p-value. Anticoagulant and antiplatelet use were not associated with incident ARIA-H.

These findings suggest that modifiable risk factors, such as untreated hyperlipidemia, may contribute to ARIA-H development. Clinicians should consider prioritizing interventions that reduce the impact of cardiovascular diseases, such as hyperlipidemia, in order to decrease the likelihood of naturally occurring ARIA-H. Further research is needed using EXPEDITION 2 and 3 data in order to validate these findings, however these initial insights may help guide the clinical decisions moving forward.