Table 1.

Summary of main findings per condition and domain

Parameter	Functional cognitive disorder***	Fibromyalgia	Chronic fatigue syndrome	Functional neurological disorder†
Cognitive symptoms	Memory Language (word finding)	Attention/concentration Memory Language (word finding)	Attention/concentration Memory Language (word finding) Reasoning	Attention/concentration Memory Language (word finding)
Objective neuropsychological deficits
Memory		Vulnerability to distraction Explicit worse than implicit memory*	Impaired registration and consolidation* Working memory disruption by abnormal attention/information processing*	Working memory**
Attention/concentration		Selective/divided attention* Bias towards emotionally negative information**	Divided attention Executive function of attention** Bias towards threatening stimuli*	Attention** Attentional bias towards social threatening stimuli**
Executive functions		Cognitive inhibition**
Information processing			Slow	Slow**
Language		Verbal fluency*	Verbal fluency**
Social cognition		Alexithymia** Recognising others’ emotions*		Alexithymia* Affect expression and recognition**
Consistency on repeat assessment			Increased performance variability
Factors related with neuropsychological deficits		Pain*	Fatigue**	Psychopathology**
Discrepancies between symptoms and objective deficits	Symptoms>objective deficits	Symptoms>objective deficits	Symptoms>objective deficits	Symptoms>objective deficits**
Performance validity/effort testing	A minority fail validity testing	Only a minority fail validity testing*	Rare failures on validity testing*	Overall, only a minority fail validity testing
Neurobiology of cognitive impairment	No structural damage	No structural damage* Dysfunction of a fronto-parieto-temporal network involved in attention, memory and executive functions, as well in emotion and pain processing	No structural damage* Dysfunction of the working memory network	No structural damage
Others	Memory perfectionism Overinterpretation of attentional lapses Heightened self-monitoring for cognitive errors Low memory self-efficacy		Heightened perception of effort

*, some evidence but inconsistent between studies; **, some evidence but particularly inconsistent and/or scarce; ***Proposed features.

†Non-epileptic attacks and functional movement disorders.