Differential Effects of Anticholinergic Medications in a Human Neuronal Model of AD

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AbstractBackgroundAnticholinergic (ACh) use remains common in older adults despite evidence of safety risks, including dementia risk. Evidence from population studies suggests that dementia risk may vary by ACh class. This variation might be explained by confounding by indication. In vitro models, using human neural cells where cells are directly experimentally exposed to a drug and phenotypic outcomes are measured, may address this issue. We identified classes of ACh medications that have different degrees of dementia risk based on a population study. We then treated human induced pluripotent stem cell‐derived neurons (hiPSC‐Ns) with each medication and performed cellular assays to examine the effects on AD phenotypes.MethodWe used CRISPR/Cas9 to generate an isogenic set of hiPSCs that harbor the autosomal dominant Swedish mutation in APP (APPSwe) and compared these to wild‐type control cells developed using the same pipeline. We differentiated neurons (hiPSC‐Ns) from these cells using established protocols in our laboratory. We treated these neurons with different classes of ACh medications: antidepressants (amitriptyline, doxepin, paroxetine), antihistamines (diphenhydramine, chlorpheniramine), bladder antimuscarinics (oxybutynin, tolterodine), and antispasmodics (atropine). As a control, we treated cells with the classic cholinergic compound carbachol. Cells were treated with two drug doses (0.01 and 0.01mM) at two time points (24 and 48hrs). We used molecular assays to test AD‐associated cellular outcomes (neurotoxicity, Amyloid beta [Ab], and pTau).ResultWe document differential effects of medications on all AD outcomes measured. Several drugs demonstrated dose‐dependent (doxepin, oxybutynin, paroxetine, amitriptyline) and/or time dependent (oxybutynin, paroxetine) neurotoxicity. We also observed differential effects on Ab secretion, with paroxetine, doxepin, and diphenhydramine lowering Ab and chlorpheniramine having no effect. Interestingly, medications not demonstrating neurotoxicity (diphenhydramine, chlorpheniramine, tolterodine, atropine, carbachol) also reduce intracellular pTau at lower concentrations.ConclusionStem cell‐derived neuronal models provide a useful strategy to complement pharmacoepidemiological studies to help distinguish molecular versus environmental actions of drugs associated with dementia risk. Preliminary results suggest that different ACh drugs have differential effects on AD‐associated cellular outcomes. Future work will test this panel of medications on hiPSC‐Ns derived from Adult Changes in Thought (ACT) cohort subjects with high and low AD genetic risk