CLarifying ABCB1's Role in Alzheimer's Disease (CLeAR-AD)

January 30, 2026 updated by: Assistance Publique - Hôpitaux de Paris

CLarifying ABCB1's Role in Amyloid Efflux and Alzheimer's Disease Risk

Alzheimer's disease is biologically defined by the accumulation of amyloid beta and tau protein, identified using cerebrospinal fluid biomarkers. The ABCB1 gene, which encodes P-glycoprotein involved in amyloid beta efflux across the blood-brain barrier, may influence Alzheimer's disease risk. We hypothesize that certain functional ABCB1 polymorphisms impair amyloid beta clearance, thereby promoting the development of biologically defined Alzheimer's disease.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

A case-control study comparing the distribution of three functional ABCB1 gene polymorphisms (3435C>T, 2677G>T/A, 1236C>T) in patients with biologically defined Alzheimer's disease versus neurological controls. We will also analyze the distribution of haplotypes derived from the combination of these three polymorphisms and investigate potential interactions between these polymorphisms and the APOE genotype, particularly the presence of the ε4 allele.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
510

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • France
      • Paris, France
        • Hôpital Lariboisière - Fernand Widal (AP - HP)

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Patients followed in a memory clinic who underwent a comprehensive clinical and paraclinical assessment, including cerebrospinal fluid biomarkers.

Description

Inclusion Criteria:

  • age ≥ 50 years,
  • available cerebrospinal fluid biomarker results,
  • an available and usable DNA sample,
  • and consent for future research use within the biobank.

Exclusion Criteria:

  • the presence of an active non-degenerative neurological disorder (for example, multiple sclerosis, infections, or tumors),
  • and missing data regarding APOE genotyping or cardiovascular risk factors

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Patients with cerebrospinal fluid amyloid and phosphorylated tau biomarkers (A+T+)
Genetic: ABCB1 genotyping
Genotyping of three single nucleotide polymorphisms (3435C>T, 2677G>T/A, and 1236C>T) associated with variation in P-glycoprotein activity, using DNA samples stored in a biobank.
Patients without cerebrospinal fluid amyloid, phosphorylated tau and total tau biomarkers (A-T-N-)
Genetic: ABCB1 genotyping
Genotyping of three single nucleotide polymorphisms (3435C>T, 2677G>T/A, and 1236C>T) associated with variation in P-glycoprotein activity, using DNA samples stored in a biobank.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Allele and genotype frequencies of ABCB1 single nucleotide polymorphisms (3435C>T, 2677G>T/A, and 1236C>T)
Time Frame: Baseline (at the time of biological sampling and clinical assessment)

Allele and genotype frequencies of the ABCB1 single nucleotide polymorphisms 3435C>T, 2677G>T/A, and 1236C>T, determined by genotyping from genomic DNA, will be compared between:

  • patients with biologically defined Alzheimer's disease (A+T+Nx), and
  • neurological control participants with a negative biomarker profile (A-T-N-). Data will be summarized as allele frequencies and genotype distributions in each group.
Baseline (at the time of biological sampling and clinical assessment)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Haplotype frequencies of ABCB1 polymorphisms (3435C>T, 2677G>T/A, and 1236C>T)
Time Frame: Baseline (at the time of biological sampling and clinical assessment)

Haplotype frequencies derived from the combination of the ABCB1 single nucleotide polymorphisms 3435C>T, 2677G>T/A, and 1236C>T, inferred from genotyping data, will be compared between:

  • patients with biologically defined Alzheimer's disease (A+T+Nx), and
  • neurological control participants with a negative biomarker profile (A-T-N-). Haplotypes will be summarized as frequency distributions within each group.
Baseline (at the time of biological sampling and clinical assessment)
Distribution of ABCB1 polymorphisms stratified by APOE ε4 carrier status
Time Frame: Baseline (at the time of biological sampling and clinical assessment)

The distribution of ABCB1 single nucleotide polymorphisms (3435C>T, 2677G>T/A, and 1236C>T) will be assessed according to APOE ε4 carrier status (ε4 carriers vs non-carriers) in:

  • patients with biologically defined Alzheimer's disease (A+T+Nx), and
  • neurological control participants with a negative biomarker profile (A-T-N-). ABCB1 allele and genotype frequencies will be summarized within each APOE ε4 stratum.
Baseline (at the time of biological sampling and clinical assessment)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Assistance Publique - Hôpitaux de Paris

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 25, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 19, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 30, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 6, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 6, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 30, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • APHP251732

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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