Medical knowledge retention: test, time and pressure

You studied physiology carefully in the second year and, during the internship, you barely remember how the renin-angiotensin system works. It is not a lack of effort: knowledge that is not used fades, and medicine asks you to keep a lot for many years. The good news is that research shows what helps you retain more and for longer.

NEXO is a daily medical diagnosis game: one clinical case a day, six progressive clues, and ICD-10 proximity feedback across five levels.

This guide gathers what studies say about how much content is lost over the course, which strategies hold knowledge, and what happens to diagnosis when time is tight.

Key points

• A large part of what is learned in the basic cycle is lost within a few months without use.
• The loss varies greatly from person to person and from subject to subject.
• Reviewing at intervals and testing yourself hold knowledge better than studying everything at once.
• Detailed knowledge drops, but the structure linking mechanism and clinical practice tends to stay.
• Time pressure reduces the number of hypotheses and accuracy; training with time is different from learning with time.

Summary

• How much knowledge is lost
• What helps retain
• What remains when detail drops
• Time pressure and diagnosis
• A week to retain more
• Adrenaline: a case against the clock in NEXO
• Frequently asked questions
• Retention checklist

How much knowledge is lost

Months without use already weigh

In a study in Hungary, third and fourth year students retook the written exams in physiology and microbiology after sixteen weeks without contact with the content (Csaba et al., 2025). Grades fell from 70.4% to 53.5% in physiology and from 72.1% to 57.3% in microbiology (Csaba et al., 2025). Retention varied greatly among students and was little related to the overall grade average, which suggests that the exam grade measures something other than the knowledge that remains (Csaba et al., 2025).

The loss changes with the subject

A systematic review on retention of basic sciences among physicians found higher retention in anatomy and the lowest in microbiology, with a score of 39.1% (Albert et al., 2024). In a longitudinal study in the United Kingdom, a small cohort of students improved in the set of basic sciences between the first and last year, with gains in anatomy and physiology and a drop only in biochemistry (Zafar et al., 2023). The authors link this difference to the relevance that students perceive in each area: what appears in clinical practice is reviewed and stays (Zafar et al., 2023).

What helps retain

Reviewing at intervals

In a trial with urology residents in the United States and Canada, one group received all study questions at once and the other received one or two per day, repeated at intervals, over several months (Kerfoot et al., 2007). The spaced group had higher grades on the online tests, and these grades remained stable over time, while those of the other group fell (Kerfoot et al., 2007). The gain, however, barely appeared on the annual residency exam (Kerfoot et al., 2007). The guide on spaced repetition shows how to set up this rhythm.

Questions with explanation

In a Harvard trial on physical examination, second year students received questions by email, answered online, and immediately saw the explanation, in repeating cycles (Kerfoot et al., 2008). At the end of the third cycle, the group that did the program had higher grades than the control group, with an effect size of 1.43 (Kerfoot et al., 2008). The same principle appears in the guide on reviewing by playing: trying to remember before seeing the answer holds more than rereading.

Reviews that return to the content

The systematic review on basic sciences points out that repeating the content improves retention, and that integrating basic sciences and clinical practice, in addition to active recall exercises, helps both remembering and reasoning (Albert et al., 2024).

Strategy	What it does	When to use
Spaced review	Returns to the content before it fades	Always, with increasing intervals
Test before the answer	Forces retrieval from memory	In each review session
Explanation after the test	Corrects and links the fact to the mechanism	Right after answering
Cases that use the basics	Gives clinical relevance to the content	When the basics seem distant

What remains when detail drops

The same systematic review concludes that detailed retention of basic sciences can decrease over time, but the conceptual framework remains essential for learning and reasoning (Albert et al., 2024). The authors cite "encapsulated" knowledge: with experience, the physician comes to summarize various mechanisms into a clinical concept and needs less to remember each detail (Albert et al., 2024).

In practice, losing the detail of a biochemical pathway is not the end of the world. What is worth protecting is the link between the mechanism and the clinical picture. The guide on how to study physiology, biochemistry and histology shows how to study the basics already thinking about that link.

Time pressure and diagnosis

Tight time reduces accuracy

In an experiment with internal medicine residents in Saudi Arabia, one group received, after each case, a warning that they were behind (ALQahtani et al., 2016). This group spent less time and had an accuracy score of 0.33, against 0.51 for the group without pressure (ALQahtani et al., 2016). Later analyses suggested that the effect appears mainly in cases of medium difficulty and in those with intermediate experience (ALQahtani et al., 2016).

Fewer hypotheses and more stress

In a second experiment by the same group, residents under time pressure had an accuracy score of 0.44, against 0.53 for the control group (ALQahtani et al., 2018). They reported more stress and generated fewer plausible alternative hypotheses, and these two paths explained part of the drop in accuracy (ALQahtani et al., 2018).

Train with a clock and learn without a clock

These results help separate two moments of study. To learn a new disease, free time leaves room to generate hypotheses and compare alternatives. To train speed with diseases you already know, the clock creates the on-call condition. The two moments complement each other when the timed session comes after study without pressure.

A week to retain more

1. Monday: study a new topic without pressure, linking mechanism and clinical practice.
2. Tuesday: test yourself on Monday's topic before rereading.
3. Wednesday: solve cases that use the topic and read the explanation for each one.
4. Thursday: review the previous week's topics with questions.
5. Friday: do a short timed session on topics you already master.
6. Weekend: return to the week's mistakes and note what changed.

Adrenaline: a case against the clock in NEXO

In NEXO, Adrenaline brings one case per day against the clock, with the same up to six clues and proximity in ICD-10 for each guess. The dose is chosen before starting and defines the time and the aids:

Dose	Time	Aids
Low	Five minutes	Area and ICD range
Medium	Three minutes	Area only
High	One minute	Only the case clues

When leaving the match, the clock stops, and the case waits for the player until the turn of the day. This pause lets timed training fit into the routine without losing the case. The low dose goes with topics still being consolidated; the high dose, with topics you already recognize confidently.

The daily case without a clock remains the space to think calmly, and the Modes screen gives access to the Archive, with previous daily cases, to return to a topic days later. The details of access to each mode are on the NEXO economy page.

If you research knowledge retention or time pressure in diagnosis and want to study these topics with NEXO, check out NEXO Researcher. To bring NEXO to your medical school, student league or residency, there is NEXO Closer. Physicians who review cases in their specialty participate through NEXO Curator, and those who create health content on social media can participate through NEXO Creators.

Frequently asked questions

How much medical knowledge is lost over time?

It depends on the topic and the person. In a study with students who retook exams after sixteen weeks, scores dropped from 70.4% to 53.5% in physiology (Csaba et al., 2025).

What helps retain content for longer?

Reviewing at intervals and testing yourself before seeing the answer. Residents who received spaced questions kept their scores stable, while the group that studied everything at once lost performance (Kerfoot et al., 2007).

Does time pressure hinder diagnosis?

In experiments with residents, time pressure reduced accuracy and the number of alternative hypotheses (ALQahtani et al., 2018). So it is worth separating unhurried study from timed practice.

Is it worth reviewing the basic cycle during the internship?

It is worth reviewing what links mechanism and clinical practice. The systematic review on basic sciences shows that detail fades, but the conceptual structure remains useful for reasoning (Albert et al., 2024).

How do the Adrenaline doses work?

The player chooses the dose before starting: low, with five minutes and help with area and ICD chapter; medium, with three minutes and area help; high, with one minute and only the case clues. When you leave, the clock stops. To learn about the game, read what NEXO is.

Retention checklist

1. Study the new topic without rushing, linking mechanism and clinical practice.
2. Test yourself before rereading at each review.
3. Read the explanation right after answering.
4. Space out the reviews with increasing intervals.
5. Use cases to give clinical relevance to the basics.
6. Practice with time only what you already know.
7. Choose the difficulty according to how solid the topic is.
8. Return to your mistakes at the end of each week.

Want to test your speed on one case per day? Play the case of the day on NEXO.

References

1. Csaba G, Szabó I, Környei JL, Kerényi M, Füzesi Z, Csathó Á. Variability in knowledge retention of medical students: repeated and recently learned basic science topics. BMC Med Educ. 2025. https://pubmed.ncbi.nlm.nih.gov/40217227/
2. Albert FA, Seidu AA, Mason HM, et al. A systematic review of medical practitioners' retention and application of basic sciences to clinical practice. BMC Med Educ. 2024. https://pubmed.ncbi.nlm.nih.gov/39272053/
3. Zafar I, Chilton J, Edwards J, Watson H, Zahra D. Exploring basic science knowledge retention within a cohort of undergraduate medical students in the United Kingdom: A longitudinal study. Clin Teach. 2023. https://pubmed.ncbi.nlm.nih.gov/37646408/
4. Kerfoot BP, Baker HE, Koch MO, Connelly D, Joseph DB, Ritchey ML. Randomized, controlled trial of spaced education to urology residents in the United States and Canada. J Urol. 2007. https://pubmed.ncbi.nlm.nih.gov/17382760/
5. Kerfoot BP, Armstrong EG, O'Sullivan PN. Interactive spaced-education to teach the physical examination: a randomized controlled trial. J Gen Intern Med. 2008. https://pubmed.ncbi.nlm.nih.gov/18612727/
6. ALQahtani DA, Rotgans JI, Mamede S, et al. Does Time Pressure Have a Negative Effect on Diagnostic Accuracy? Acad Med. 2016. https://pubmed.ncbi.nlm.nih.gov/26826069/
7. ALQahtani DA, Rotgans JI, Mamede S, Mahzari MM, Al-Ghamdi GA, Schmidt HG. Factors underlying suboptimal diagnostic performance in physicians under time pressure. Med Educ. 2018. https://pubmed.ncbi.nlm.nih.gov/30302783/