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.