Contributors:
Kaycee Sink, MD, MAS (Chief Medical Officer)
Svenja Wacker, PhD (Neuropsychology Science Director)
Memory decline is often the earliest cognitive manifestation of Alzheimer’s disease (AD) and other neurodegenerative disorders. Because impairments in learning and memory are common early in the disease course, systematic measurement of the ability to acquire, retain, retrieve, and recognize new information is a critical component of clinical outcome assessments in AD trials.
Verbal list learning tests are widely used to evaluate these memory processes.
“Verbal list learning tests remain foundational tools for assessing memory decline in Alzheimer’s disease clinical trials, offering sensitive measures of learning and episodic memory that are often affected early in the disease course, says Dr. Svenja Wacker Neuropsychology Science Director at Cogstate.
Similarities and Variations Among Verbal List Learning Tests
In these assessments, a rater presents a list of words, either unrelated or organized into semantic categories, over multiple learning trials. Participants are asked to recall the words in any order following each trial. After a delay, delayed free recall is assessed to measure spontaneous retrieval, often followed by a recognition trial in which participants identify previously presented words from a set of choices.
Several well-established verbal list learning tests share this structure, including the Hopkins Verbal Learning Test (HVLT), Rey Auditory Verbal Learning Test (RAVLT), California Verbal Learning Test (CVLT), and Cogstate’s International Shopping List Test (ISLT™). Word list learning and recall tasks are also incorporated into broader cognitive batteries and composites, such as the RBANS and ADAS-Cog.
Despite their conceptual similarities, verbal list learning tests vary in important design features that can influence sensitivity and feasibility in clinical trials.
These include:
- number of words presented (typically 8–16),
- number of learning trials (3–5),
- mode of presentation (verbal or printed),
- consistency of word order across trials,
- use of semantically grouped versus unrelated words,
- length of the delay interval,
- presence or absence of an interference task,
- and administration method (rater-administered versus digital).
Considerations for Verbal List Learning Tests as AD Trial Endpoints
When used as endpoints in AD clinical trials, verbal list learning tests must demonstrate strong scientific validity and reliability to meet regulatory expectations. Repeated administration may introduce practice effects, particularly if participants remember word lists from prior visits, potentially inflating scores and obscuring true cognitive change.
These assessments are also vulnerable to cultural bias, as direct translation of word lists may not adequately account for cultural relevance or familiarity, thereby altering task difficulty and compromising validity.
In addition, tests with longer word lists or multiple learning trials can increase participant and rater burden, especially in more advanced disease stages. High-quality data collection therefore depends on experienced, well-trained psychometric raters who are carefully calibrated to ensure standardized administration and minimize procedural errors.
To mitigate risk and deliver high-quality, reliable data, trial sponsors should consider implementing a comprehensive framework for rater support including rater training, central monitoring, and central rating.
Another option to mitigate rater error is utilizing a digital verbal list learning tool, such as the Cogstate International Shopping List Test (ISLT). The ISLT was designed specifically to meet the demands of multinational clinical trials. While grounded in classic episodic memory assessment, it was engineered for cross-cultural use through carefully selected, easily translatable stimuli and has been validated across 100+ languages and regions. Digital administration ensures consistent delivery, automated scoring, and reduced rater variability, while large stimulus pools help minimize practice effects in longitudinal studies. As a result, the ISLT combines strong construct validity and sensitivity to early cognitive impairment with operational advantages such as brief administration time, minimal training requirements, and high scalability, making it a highly effective and reliable tool for assessing verbal list learning in global clinical trials.
Wrapping Up
“When thoughtfully selected and rigorously implemented, with attention to test design, cultural adaptation, rater training, and practice effects, verbal learning assessments can provide robust, clinically meaningful endpoints,” says Wacker.
As AD research continues to shift toward earlier disease stages, well-validated verbal memory measures will be essential for detecting subtle cognitive change and demonstrating treatment-related effects that matter to patients and regulators alike.
This blog is part of a series exploring the individual scales reviewed in our Alzheimer’s Disease Clinical Trial Endpoint Guide. Access the full guide here. Interested in learning more? We are happy to discuss endpoint selection with your team in more depth. Contact us today.
