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.

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.

Diagnostic techniques at a glance

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.

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.

The longer explanations already on this page remain below. Individual technique pages will be developed and reviewed separately.

Internal inconsistency

The clinician identifies a specific mismatch within a cognitive ability, such as better use during ordinary interaction than during focused testing. This is the central positive concept. Ordinary fluctuation, distress or a normal screening score alone is insufficient. [2]

Conversation versus formal performance

Detailed, coherent accounts can be compared with the particular impairment claimed during testing. The comparison must concern the same ability and allow for anxiety, pain, fatigue, language and sensory barriers. It is supportive clinical reasoning, not a test of honesty. [1][2]

Everyday function and collateral history

With consent, the clinician compares the person’s account, a supporter’s observations and actual daily tasks. A specific inconsistency may be useful, but compensatory strategies can preserve daily function despite neurological disease. Disagreement alone is not a positive sign. [1][2]

Neuropsychological pattern

Assessment compares acquisition, delayed recall, recognition and other domains. Particular internal discrepancies may support FCD; isolated low scores or a normal total score do not. Coexisting neurological disease and test conditions remain part of interpretation. [2][3]

Proposed diagnostic risk model

A published model combines clinical features to estimate diagnostic likelihood. It supports structured assessment rather than replacing judgment. Its development population and validation limits prevent treating the score as a universal diagnostic threshold. [1]

Functional cognitive disorder checklist

An 11-item and shorter 7-item checklist were developed through literature review, expert consensus and a multicentre pilot study. Results support further use and study, but prospective blinded external validation was still needed. This is not a self-diagnosis checklist. [4]

Performance-validity testing

These tests help interpret whether cognitive scores represent usable estimates of ability. Passing or failing does not itself diagnose FCD, malingering or a particular cause. Interpret results within the full clinical and testing context. [2][3]

Longitudinal assessment and investigations

Follow-up and selected laboratory, imaging or other tests address plausible competing or coexisting causes. Stability may contribute to the formulation but does not prove FCD. A positive diagnosis should explain current findings and what would prompt review. [2]

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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.

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.”

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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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]

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

  1. Define the cognitive complaint, onset, course, variability and functional consequences. Ask for specific recent examples rather than accepting or rejecting a global label such as “memory loss.”
  2. Observe how the patient follows the conversation, recalls autobiographical and appointment details, uses aids, corrects errors and manages multistep information during the encounter.
  3. With consent, obtain collateral examples of both difficulty and preserved ability. Interpret differences between accounts respectfully and in context.
  4. Use validated cognitive screening or neuropsychological assessment when it will answer a clinical question. Follow test-security, language, education and performance-validity standards.
  5. Look for internal inconsistency across history, observed behaviour, day-to-day function and test performance. The contrast should be clinically meaningful and not explained more plausibly by task demands or fluctuating health.
  6. Evaluate sleep, pain, fatigue, medication and substance effects, mood, anxiety, ADHD, epilepsy, head injury, neurodevelopmental factors, neurodegenerative disease and other relevant causes or comorbidities.
  7. Explain the positive formulation without saying “nothing is wrong.” State the degree of certainty and arrange follow-up if progression or a new pattern emerges.

Media contributor brief

Use a fictional case with an actor or an annotated diagram showing four information sources:

  1. The person’s description of the problem.
  2. Examples of everyday difficulty and preserved ability.
  3. Abilities observed during the appointment.
  4. Results of appropriate validated assessment and medical evaluation.

Show how the clinician looks for a meaningful pattern across all four, rather than setting up a “gotcha” memory test. Do not display copyrighted or secured test items, scoring keys or a real patient’s identifiable daily-life details. Make clear that one inconsistency is a clue, not a diagnosis.

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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Research and Sources

Evidence notes

  • The proposed diagnostic risk model describes internal inconsistency as central to identifying FCD and discusses features that must be distinguished from neurodegenerative and other cognitive disorders. It is a proposed model, not a universally validated diagnostic calculator. [1]

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.

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

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For Family, Friends, and Other Supporters
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