Cholinesterase inhibitor use does not significantly influence the ability of ¹²³I-FP-CIT imaging to distinguish Alzheimer’s disease from dementia with Lewy bodies

Abstract

Background: ¹²³I-labelled 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (¹²³I-FP-CIT) imaging is a diagnostic tool to help differentiate dementia with Lewy bodies (DLB) from Alzheimer’s disease (AD). However, in animals, cholinesterase inhibitors (ChEi) have been reported to reduce radioligand binding to the striatal dopamine transporter. As ChEi are frequently used in people with dementia, it is important to determine whether their use affects ¹²³I-FP-CIT uptake in the striatum.

Objective: To clarify whether chronic ChEi therapy modulates striatal dopamine transporter binding measured by ¹²³I-FP-CIT in patients with AD, DLB and Parkinson’s disease with dementia (PDD).

Design: Cross sectional study in 99 patients with AD (nine on ChEi, 25 not on ChEi), DLB (nine on ChEi, 19 not on ChEi) and PDD (six on ChEi, 31 not on ChEi) comparing ¹²³I-FP-CIT striatal binding (caudate, anterior and posterior putamen) in patients receiving compared with those not receiving ChEi, correcting for key clinical variables including diagnosis, age, sex, Mini-Mental State Examination score, severity of parkinsonism and concurrent antidepressant use.

Results: As previously described, ¹²³I-FP-CIT striatal uptake was lower in DLB and PDD subjects compared with those with AD. Median duration of ChEi use was 180 days. ¹²³I-FP-CIT uptake was not significantly reduced in subjects receiving ChEi compared those not receiving ChEi (mean percentage reduction: AD 4.3%; DLB 0.7%; PDD 6.1%; p = 0.40). ChEi use did not differentially affect striatal ¹²³FP-CIT uptake between patient groups (p = 0.83).

Conclusions: Use of ChEi does not significantly influence the ability of ¹²³I-FP-CIT imaging to distinguish AD from DLB.