FND Education Project

REFERENCE · DIAGNOSIS

Functional Cognitive Disorder

Refers to:

  • memory, attention or concentration difficulty;
  • word-finding and mental-efficiency problems; and
  • “brain fog” only when it forms part of an assessed functional cognitive presentation.

Scope boundary: Speech-motor blocking belongs on the speech page, and altered awareness within an event may require functional-seizure assessment. Cognitive symptoms can also arise from sleep, medication, pain, migraine, mood, neurological disease and other causes.

Quick Reference

Presentation: Assess positive internal inconsistency and other causes of cognitive symptoms, then measure everyday impact and support needs separately.

More techniques: See the full list below.

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For the Person With FND

You might lose the thread of a conversation, reread a message without taking it in, forget an intended task or struggle to organize familiar steps. These experiences help describe the problem; they do not by themselves establish FCD.

Functional Cognitive Disorder (FCD) can involve disabling problems with memory, attention, concentration, word finding or thinking. The difficulty is real. The central positive feature is internal inconsistency: a clinically meaningful difference in access to the same cognitive ability across contexts, after accounting for task demands and other explanations. Ordinary fluctuation or one good performance is not enough.

For example, the detailed history a person gives during an appointment may show abilities that appear unavailable in a formal task, or everyday successes may not fit the degree of loss expected from the reported problem. These are clues to examine, not contradictions that prove a person is unreliable. [1]

Normal imaging or one average screening score does not diagnose FCD. Sleep, pain, migraine, fatigue, medication, mood, ADHD, sensory impairment and neurological disease may independently affect cognition or coexist with FCD; they are not automatically part of FCD. Recognition, visual recall and imagery complaints deserve assessment but are not established hallmark signs.

New loss of recognition of highly familiar people, familiar knowledge or spatial abilities needs reassessment; sudden changes need urgent assessment. Getting lost or making unsafe medication or financial errors also warrants review.

Understanding the diagnosis and measuring its impact

Assessment should answer both “What explains this pattern?” and “What support helps me manage daily life?” An occupational therapist can examine activities that matter to you; neuropsychology can examine thinking skills in more detail, and speech-language therapy may help assess communication demands. The team should choose assessments for the questions you need answered. [2][5]

Ask the team to record aids, reminders, extra time and help that make an activity possible. Success with those supports does not show what would happen without them. A short appointment also leaves open whether you can repeat the activity and what recovery costs. These are practical assessment questions, not assumptions about every person with FCD.

Daily difficulties can affect confidence, relationships, work and participation. Discuss distress and support alongside performance; a mood score does not establish why a cognitive problem happens. Measurement should help plan care, not become a daily test you have to pass. [2][5] See the plain-language FCD background.

Cognitive difficulty may fluctuate or remain for long periods

Functional cognitive symptoms can change markedly within a day or between situations, especially as attention and task demands change. A person may have a period in which words, sequencing or concentration become much less accessible and later function better again; another person may have persistent difficulties over a long period. Fluctuation is part of the history, not proof that the person could perform normally by choice.

When a familiar cognitive episode starts, reduce incoming information and multitasking. Pause the task, use one written step, calendar, checklist or other established external aid, and resume only when it is safe and useful. Sudden confusion, altered consciousness, new focal neurological symptoms or a major departure from the established pattern needs medical assessment.

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For Family, Friends, and Other Supporters

Do not quiz the person, secretly keep score or use a remembered success to dismiss a later difficulty. With permission, you can provide examples of what has changed, what remains possible and how the pattern affects daily life. Try to describe actual events rather than deciding whether the person “really forgot.”

For assessment, describe what you actually do to help—setting up a task, giving reminders, checking errors or taking over a step. With permission, explain what happens after the appointment or activity as well as during it. Your account supplements the person’s perspective; disagreement is something to understand, not proof of a diagnosis.

When thinking or word finding suddenly becomes harder

Reduce the amount of information being presented. Use one question or instruction at a time, allow extra processing time and point to the person’s usual written or electronic aid. Avoid repeatedly correcting, quizzing or demanding recall while the person is overloaded.

A short period of difficulty and a longer cognitive flare can both be genuine. If useful, note the task, competing demands, duration, associated FND or migraine symptoms and recovery. New confusion, a rapid change in thinking or other urgent neurological or medical symptoms still needs appropriate assessment.

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For Clinicians and the Care Team

Featured technique: Structured history and cognitive assessment looking for internal inconsistency.
Diagnostic method: Compare the reported difficulty with observed abilities and valid assessment results while evaluating other causes of cognitive symptoms.
Media needed: A fictional appointment example or annotated comparison diagram; never publish protected cognitive-test material.

Further reading: Everything We Know About FCD explains cognitive processes, visual experiences and recovery principles. These experiences do not add new positive signs to the inventory below.

Characterize the relevant domain: attention, encoding, working memory, language/semantic access, executive function, recognition/familiarity, visual or nonverbal recall, visuospatial function and imagery as indicated. Face-recognition and imagery complaints are not established hallmark FCD signs; investigate the differential. Internal inconsistency should concern the same domain with context and demands accounted for. A single good performance, normal scan, normal score or treatment response cannot establish FCD. [1][2]

A measurement plan alongside diagnosis

The OT measurement guide covers COPM, EFPT, PROMIS Cognitive Function and an authored task/context/support record. It distinguishes self-report, observed performance and diagnostic evidence, with official tool access and FCD-specific evidence limits. These outcome tools are not extra positive signs of FCD.

Coordinate the referral question: neurology/general practice for the clinical differential and follow-up; neuropsychology for cognitive profiles and validity; OT for daily activity and support; speech-language therapy for relevant cognitive-communication demands. Roles overlap and depend on local competence and services. Agree who integrates the findings and supplies an accessible written plan.

Episodic and prolonged presentations

Characterize fluctuations rather than reducing them to “good days and bad days”: onset, duration, frequency, cognitive domain, task and sensory load, fatigue, pain, sleep, medication, mood, migraine or seizure context, and recovery. Internal inconsistency may include preserved function at some times and impaired access at others, but the contrast must be clinically meaningful and not better explained by differing task demands or another disorder.

For episodic deterioration, develop a brief plan using reduced cognitive load, single-tasking and established external supports. Document the person’s baseline and safety-sensitive activities so a new progressive or acute pattern is not automatically attributed to FCD.

Technique outline: assessing internal cognitive inconsistency

The original seven-step outline is preserved in Internal Inconsistency and Clinical Assessment.

Media contributor brief

The original brief is preserved in Clinical Assessment: Media and Accessibility.

Recovery reading: Thirteen detailed Functional Cognitive Disorder recovery pages, with practical support, individual safety limits and clear distinctions between clinical guidance and early research.

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Diagnostic techniques at a glance

These brief entries describe signs, observations, criteria and investigations clinicians may consider. They are not a checklist of tests everyone needs. Evidence and limitations differ for each entry; a positive sign must fit the whole clinical picture, including possible coexisting disease.

All eight original descriptions remain in the preserved inventory, followed by one dated research addition. Detailed pages group related questions; they are not a compulsory battery.

Internal inconsistency

Internal inconsistency — Positive same-domain clinical comparison.

Conversation versus formal performance

Conversation versus formal performance — Interpret conversational and testing demands carefully.

Everyday function and collateral history

Everyday function and collateral history — Consensual daily examples, supports and context.

Neuropsychological pattern

Neuropsychological pattern — Cognitive profiles and their diagnostic limits.

Proposed diagnostic risk model

Proposed diagnostic risk model — A small-cohort development model.

Functional cognitive disorder checklist

Functional cognitive disorder checklist — Pilot evidence and external-validation needs.

Performance-validity testing

Performance-validity testing — Interpretability of test results, with limits.

Longitudinal assessment and investigations

Longitudinal assessment and investigations — Course over time and clinically selected investigations.

FCD-Q8 preliminary classifier

Research addition — October 4, 2026 — Separate early-stage questionnaire evidence; not a daily-function measure.

Research and Sources

Evidence notes

  • The clinical framework centres on positive internal inconsistency with appropriate differential assessment. Model and checklist evidence does not make a normal screen sufficient. [1][2][4]
  • A 2026 scoping review of 23 studies found varied neuropsychological patterns and no standalone cognitive test with diagnostic specificity. The earlier clinic comparison provides one example, rather than a universal FCD profile. [3][7]
  • OT consensus supports measuring activity and participation; selected tool details and population limits are in the dedicated measurement guide. That guide does not claim FCD-specific validation of its tool set. [5]
  • FCD-Q8 is a separately dated preliminary diagnostic research addition. Its selected study does not establish everyday disability measurement or validate the Cabreira checklist. [6]

Citation table

Citation Full citation
[1] McWhirter L, Ritchie C, Stone J, Carson A. Identifying functional cognitive disorder: a proposed diagnostic risk model. CNS Spectrums. 2022;27(6):754–763. FND-CIT-0026. https://doi.org/10.1017/S1092852921000845
[2] Ball HA, McWhirter L, Ballard C, et al. Functional cognitive disorder: dementia’s blind spot. Brain : a journal of neurology. 2020;143(10):2895-2903. DOI. PMID: 32791521. FND-CIT-0071.
[3] Ball HA, Swirski M, Newson M, et al. Differentiating Functional Cognitive Disorder from Early Neurodegeneration: A Clinic-Based Study. Brain sciences. 2021;11(6):800. DOI. PMID: 34204389. FND-CIT-0141.
[4] Cabreira V, Alty J, Antic S, et al. Development of a diagnostic checklist to identify functional cognitive disorder versus other neurocognitive disorders. BMJ neurology open. 2025;7(1):e000918. DOI. PMID: 40034653. FND-CIT-0140.
[5] Nicholson C, Edwards MJ, Carson AJ, et al. Occupational therapy consensus recommendations for functional neurological disorder. Journal of Neurology, Neurosurgery & Psychiatry. 2020;91(10):1037–1045. DOI. FND-CIT-0011.
[6] García-Roldán E, Almodóvar-Sierra Á, Luque-Tirado A, et al. Preliminary Validation of the FCD-Q8 Tool in Functional Cognitive Disorder and Early Alzheimer’s Disease: A Biomarker-Verified Case–Control Study. European Journal of Neurology. 2025;32(11):e70383. DOI. FND-CIT-0260.
[7] Mammì A, Reuber M, Pascarella A, et al. Neuropsychological assessment in functional cognitive disorder: a scoping review. Psychiatry Research. 2026;117508. Published online October 8, 2026; journal pre-proof. DOI. FND-CIT-0270.

Technique outline created: August 24, 2026 · Cognitive-neurology and neuropsychology review pending

For the Person With FND
For Family, Friends, and Other Supporters
For Clinicians and the Care Team
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