Functional Cognitive Disorder and Mild Cognitive Impairment: A Thin Line

Abstract

Aims

Functional cognitive disorders (FCDs) refer to conditions where patients present with persistent problematic subjective memory complaints that are not consistent with their observed level of cognitive functioning. The demonstrated symptoms are also not in keeping with a recognized psychiatric or neurodegenerative process. FCD is likely to be underdiagnosed in clinical practice with the place-holder label of mild cognitive impairment being used in some cases due to lack of clarity about its symptomatology. In this paper, we describe two cases whose presentations were suggestive of FCDs.

Methods

Mrs X, 53 years old female not previously known to mental health services referred for increasing difficulties with her memory over 2 years which she believed was impacting her activities of daily living. She has a history of ischaemic heart disease, fibromyalgia, Insulin-dependent diabetes mellitus, depression, and polycystic ovarian syndrome. On assessment MOCA = 15/30, and MMSE = 25/30.

Mr Y, 57 years old male not known to mental health services. Although, has been treated for anxiety and depression by GP. He presented with a 3-year history of struggling with his memory. He reported being forgetful of appointments and he has to paste sticky papers on the fridge for reminders. Similarly, he has a diagnosis of Fibromyalgia and essential hypertension. On Assessment MOCA – 19/30 and MMSE – 25/30.

Results

FCDs can be quite challenging because the clinical picture overlaps with other neurodegenerative conditions. Typically, patients report issues around memory function in the absence of relevant neuropathology and with evidence of inconsistency between symptoms reported and observations at assessment. Regarding our cases, the primary presenting issues were increasing difficulties with memory, and forgetfulness. Other noteworthy observations were a mismatch between their scores in the MOCA, MMSE, their level of functioning, and reported memory problems. Neurological examinations and neuroimaging were not suggestive of any neurodegenerative disorders. A differential diagnosis of functional cognitive disorder was considered due to the discrepancies between symptoms reported, the level of their functioning, observations at assessments as well as absence of relevant neuropathology on imaging.

Conclusion

FCD is a condition that is common in clinical practice but underdiagnosed. Hence, it is imperative that clinicians keep this diagnosis in mind when patients present with memory difficulties that do not meet the diagnostic criteria for dementia and is not due to a recognized medical or psychiatric condition. Correctly identifying and diagnosing FCD can positively impact patient outcomes.