Review Neuropsychological evaluation of functional cognitive disorder: a narrative review 2023 Silverberg and Rush

[Andy]

Objective: To critically review contemporary theoretical models, diagnostic approaches, clinical features, and assessment findings in Functional Cognitive Disorder (FCD), and make recommendations for neuropsychological evaluation of this condition. Method: Narrative review.

Results: FCD is common in neuropsychological practice. It is characterized by cognitive symptoms that are not better explained by another medical or psychiatric disorder. The cognitive symptoms are associated with distress and/or limitations in daily functioning, but are potentially reversible with appropriate identification and treatment. Historically, a variety of diagnostic frameworks have attempted to capture this condition.

A contemporary conceptualization of FCD positions it as a subtype of Functional Neurological Disorder, with shared and unique etiological factors. Patients with FCD tend to perform normally on neuropsychological testing or demonstrate relatively weak memory acquisition (e.g. list learning trials) in comparison to strong attention and delayed recall performance. Careful history-taking and behavioral observations are essential to support the diagnosis of FCD. Areas of ongoing controversy include operationalizing “internal inconsistencies” and the role of performance validity testing. Evidence for targeted interventions remains scarce.

Conclusions: Neuropsychologists familiar with FCD can uniquely contribute to the care of patients with this condition by improving diagnostic clarity, richening case formulation, communicating effectively with referrers, and leading clinical management. Further research is needed to refine diagnosis, prognosis, and treatment.

Paywall, https://www.tandfonline.com/doi/full/10.1080/13854046.2023.2228527

 

[Sid]

I take it FCD is some new name for brain fog.

 

[SNT Gatchaman]

I take it FCD is some new name for brain fog.

I'm afraid so.

The contemporary literature frames FCD as a subtype of Functional Neurological Disorder (FND). The defining feature of FCD is self-reported cognitive difficulties (e.g. forgetfulness, difficulty concentrating, and brain fog) that cause significant distress and/or disrupt daily activities but are not fully attributable to brain injury or disease. As in other subtypes of FND, symptoms in FCD are subjectively experienced as real and involuntary.

 

[SNT Gatchaman]

Consensus-based diagnostic criteria for FCD were proposed in 2020, as follows: (1) one or more symptoms of impaired cognitive function, (2) clinical evidence of internal inconsistency, 3) symptoms or deficit that are not better explained by another medical or psychiatric disorder, and 4) symptoms or deficit that cause clinically significant distress or impairment in social, occupational, or other important areas of function, or warrants medical evaluation.

The concept of internal inconsistency is central to this updated view of FCD. It attempts to continue to the field’s movement away from diagnosing FND based on the exclusion of other conditions, and towards a diagnosis based on positive rule-in signs (e.g. Hoover’s sign for functional leg weakness).

Internal inconsistency in FCD is operationally defined as cognitive symptoms that are in excess of or incompatible with observed performance.

The immediate response would be: "not sure how that's internal inconsistency if someone external is doing the counter-claiming." But they discuss this next (though again with the "promising") —

The concept of internal inconsistency in FCD is promising but requires refinement. One concern is that certain examples of “internal” inconsistencies are better regarded as “external” inconsistencies because they involve contrasting different sources of information (e.g. discordance between the patient’s self-reported symptoms and observations by family members).

Also —

We also do not know the base rates of internal inconsistencies in healthy individuals.

Speaking of internal inconsistency —

Examples of internal inconsistencies not associated with FCD include: (a) [...] (b) subjective cognitive symptoms in migraineurs that do not align with neuropsychological impairment at the time of the evaluation because migraine-related impairment is episodic [...] (c) and (d).

which is later followed with —

Differential diagnosis can be challenging. Opinion leaders recommend that a diagnosis of FCD should be established on the basis of internal inconsistencies that suggest a patient’s cognitive abilities are better (at least at times) than they perceive them to be.

 

[SNT Gatchaman]

A brief moment of good news —

Little long-term natural history data are available on FCD. In one small cohort (n=28), participants performed similarly on neuropsychological testing 10 years after diagnosis of FCD and none developed dementia.

Although I might develop concussion from all the face-palming with these next snippets. It's like they haven't read any biological science about what goes on in the brain or body at all —

The onset and course of FCD is often different from neurological disorders it mimics. For example, cognitive symptoms that start only days to weeks after a concussion/head injury or do not improve (or even worsen) over the weeks to month following injury would be more consistent with possible FCD.

FCD is typically associated with somatic symptoms and/or functional disorders involving other organ systems. [...] Many patients with FCD struggle with poor sleep quality

Oh and you betcha it can co-exist —

FCD can co-occur with neurocognitive disorders, just as functional seizures are more common in patients with epilepsy and patients with Parkinson’s disease can have functional motor symptoms. In FCD, cognition is the primary presenting concern. However, functional cognitive symptoms may be a secondary feature of other conditions, such as motor FND, fibromyalgia and chronic fatigue syndrome, post-concussion syndrome, and long COVID.

A-ight, now we're entering tiger country —

FCD is thought to share predisposing, precipitating, and perpetuating factors with FNDs as well as with cognitive symptoms occurring in the context of fibromyalgia, chronic fatigue syndrome, and post-concussion syndrome.

Patients with FCD may also report general cognitive inefficiency or decline using terms such as “brain fog” or descriptions like feeling “less sharp”

These may include adverse childhood events, alexithymia, alterations in limbic network connectivity, a triggering physical or psychologically traumatic event, maladaptive illness beliefs, and somatic hypervigilance.

Contemporary diagnostic criteria for FCD imply that neuropsychological testing is unnecessary because a diagnosis can be made on the basis of internal inconsistencies identified through clinical interview.

Note for @dave30th —

However, inter-rater reliability and diagnostic accuracy for most positive signs of FCD have not been established. Most are based on 1–2 small studies with substantial methodological limitations (e.g. no clinician blinding).

And then this distinction —

Some patients with FCD have more striking symptoms that are not seen in healthy people or neurological populations, such as a dense retrograde amnesia without a temporal gradient and/or a dense anterograde amnesia that “resets” upon awakening each day

That last bit sounds like you can't form new memories over any given day, but then you wake up and you find you do have the memories? However the reference seems to relate to Case E in which case it's the opposite: "She gave an emotional account of normal memory for the course of 1 day, but waking-up each morning with no recall of the previous day."

Isn't the whole point that short term memory is consolidated during sleep with new neural connections in the hippocampus? Any possibility that could relate to interference with processes that should normally occur during sleep? You did state that FCD was strongly associated with sleep disturbance after all. Maybe it's time-varying brain dysfunction, such as - oh I don't know - metabolism? What's that, oh you haven't looked because "Opinion leaders recommend that a diagnosis of FCD should be established on the basis of internal inconsistencies". Gotcha.

Worth having a read through the referenced: Functional Cognitive Disorder: Differential Diagnosis of Common Clinical Presentations (2022, Archives of Clinical Neuropsychology) although it too is pay-walled. (This specialty doesn't seem overly keen on just anyone being able to read their publications.)

There's more including the obligatory hardware/software explanation, which they seem to indicate is nonsense for patient consumption.

 

[SNT Gatchaman]

Treatments —

Patients with FCD could be directed to educational resources to learn more about their condition (e.g. neurosymptoms.org) and get peer support in an anti-stigmatizing setting (e.g. fndhope.org).

Unfortunately, there is not yet strong evidence for any FCD-specific therapies. One small randomized waitlist controlled trial suggested that group-based cognitive behavioral therapy targeting maladaptive memory beliefs may be effective.

Acceptance and commitment therapy is also being studied as a potential treatment for FCD.

No doubt both are "promising".

Metacognitive training is a strong treatment candidate on theoretical grounds, however, a feasibility randomized controlled trial suggested negligible or even reverse treatment effects

The conclusion wouldn't go amiss in r/self-awarewolves —

Neuropsychological evaluation of FCD can be challenging. Just as in other medical specialities, when evaluation is handled poorly, the neuropsychologist can exacerbate frustration and stigma, and perpetuate symptoms and disability. In contrast, the neuropsychological evaluation can play a key role in improving diagnostic clarity, richening the case formulation, and identifying predisposing and perpetuating factors that could be targeted in treatment.

 

[Sean]

>The concept of internal inconsistency in FCD is promising but requires refinement.

It requires robust validation first.

>Contemporary diagnostic criteria for FCD imply that neuropsychological testing is unnecessary because a diagnosis can be made on the basis of internal inconsistencies identified through clinical interview.

What could go wrong?

>Neuropsychological evaluation of FCD can be challenging.

Ephemeral fantasies are always hard to pin down.

----

For a field with so little substance, it sure makes a loud noise.

 

[Trish]

Internal inconsistency in FCD is operationally defined as cognitive symptoms that are in excess of or incompatible with observed performance.

This sort of nonsense is, I think, contradicted by the findings from the study on this thread:
Cognitive impairment in long COVID and short duration ME patients is mediated by orthostatic hemodynamic changes, 2023, Vernon et al

 

[dave30th]

Note for @dave30th —

So basically, don't bother to test anything, we can just tell. Just like the claim that Hoover's sign is 100% specific for FND leg weakness when the studies are shit.

 

[rvallee]

So basically, don't bother to test anything, we can just tell. Just like the claim that Hoover's sign is 100% specific for FND leg weakness when the studies are shit.

Yup. Don't look, trust us, we're experts.

 

[Hutan]

It's quite depressing, isn't it?

These people think it's fine to dump people in a psychosomatic bucket, seemly oblivious to the enormous harm it causes to the people who come to them for help. And, it's only harm (destroying trust between the patient and their doctors and indeed making people mistrust the whole medical system; alienating friends and family by suggesting that believing the person is facilitating their illness; providing justification for limited support from government and insurance companies; greatly slowing research that might actually alleviate suffering; wasting scarce public and private funds on treatments that have not hope of helping; corroding the public's understanding of science, making a belief in magic entirely acceptable in medical hypotheses ...)

There's no upside, because there is no evidence that these perpetually 'promising' treatments actually help anyone. It's all harm and no benefit, as far as the patient goes.

 

[livinglighter]

This is very concerning to read.

 

[ToneAl]

From what ibhave read and tried to understand most of these tests and diagnosises are in the mind of the physician. So what we get is mostly biased diagnosis and lots of missed conditions. So the whole construct is rubish