REFERENCE · DIAGNOSTIC TECHNIQUES

Functional Cognitive Disorder Diagnostic Inventory

All eight original entries retain their descriptions and source associations. One separately dated research addition follows them. These are not nine validated bedside tests. Outcome measures in the [OT guide](03-everyday-function-and-ot-measurement.md) are a separate measurement resource, not additions to the diagnostic-sign count.

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Internal Inconsistency and Clinical Assessment · Neuropsychological Assessment and Validity · Everyday Function and Occupational Therapy Measurement · FCD Diagnostic Models and Checklists

Diagnostic techniques at a glance

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]

Research addition — October 4, 2026

FCD-Q8 preliminary classifier

The eight-item FCD-Q8 is a separate preliminary diagnostic classifier studied against early Alzheimer’s disease in a selected memory-clinic sample. It is not a disability outcome measure or the Cabreira brief checklist. See the models guide for sample, accuracy and validation limits. [5]

Research and Sources

The original four local source numbers are preserved. The fifth supports only the dated research addition.

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]	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.

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