Introduction: Functional Cognitive Disorder (FCD) is poorly understood. We sought to better characterise FCD in order to inform future diagnostic criteria and evidence based treatments. Additionally, we compared FCD patients with and without co-morbid depression, including their neuropsychological profiles, to determine whether these two disorders are distinct.
Methods: 47 FCD patients (55% female, mean age: 52 years) attending a tertiary neuropsychiatric clinic over a one year period were included. We evaluated sociodemographic characteristics and clinical features including presentation, medications, the presence and nature of co-morbid psychiatric or physical illnesses, and the results of neuropsychometric testing.
Results: 23/47 (49%) patients had co-morbid depression. Six had cognitive difficulties greater than expected from their co-morbid conditions suggesting "functional overlay". 34 patients had formal neuropsychological testing; 12 demonstrated less than full subjective effort. 16/22 (73%) of the remaining patients had non-specific cognitive impairment in at least one domain. There were no significant differences between those with and without co-morbid depression.
Conclusions: Our study informs future diagnostic criteria. For example, they should not exclude patients with co-morbid psychiatric illness or abnormal neuropsychometric testing and clinicians should remain open to the possibility of "functional overlay". Furthermore, FCD and depression are distinct disorders that can exist co-morbidly.
Keywords: Functional Cognitive Disorder; clinical characteristics; depression; memory clinic; neuropsychometry.