In the daily clinical practice of diagnosing and treating patients with persistent somatic symptoms (PSS), we see many patients with cognitive symptoms, such as memory problems or difficulty concentrating. Some patients experience a lack of mental clarity, also referred to as ‘brain fog’.
Author: Lineke Tak
When cognitive symptoms are severe, neurodegenerative disorders like dementia are to be considered. The authors of the review described here (McWirther e.a., 2019) found it remarkable that a large number of studies into the diagnosis and treatment of neurodegenerative disorders is conducted, yet very little attention is given to the more common occurrence of functional cognitive symptoms. In other words: real cognitive problems without a clear somatic explanation.
Isolated functional cognitive symptoms can be present as part of a functional cognitive disorder. These symptoms can also manifest themselves as part of other disorders, such as a functional movement disorder, psychogenic non-epileptic seizures, fibromyalgia, chronic fatigue syndrome or a pain disorder.
A systematic review was conducted to study how often the diagnosis ‘functional cognitive disorder’ was given in memory clinics and what the clinical characteristics were. The review included 38 studies and a total of 13,637 patients. The authors found that 53% of patients who visited a memory clinic received a diagnosis of dementia. About 24% of these patients appeared to have functional cognitive problems.
Clinical findings among people with functional cognitive problems are largely inconsistent. Cognitive problems can be strongly dependent on the situation (e.g., occurring at home but not at the doctor’s office). Repeated cognitive tests may show variations in results within the same patient. This is also observed in the case of functional movement disorders, where inconsistencies are a positive diagnostic criterion for functional problems. It is important to stress that inconsistencies are characteristic in functional cognitive problems, or else it could be unjustly concluded that the patient is underachieving or simulating.
Table 1: Examples of ‘positive symptoms’ in behaviour and language that might indicate functional cognitive disorders (McWirther e.a., 2019)
| functional cognitive disorders | neurodegenerative brain disorder |
| Patient visits alone | Patient visits with a companion or carer |
| Patient is aware of the problem | Patient is aware of the problem – It is mainly others that are aware of the problem |
| Patient answers independently | Patient looks at companion when asked a question (head-turning sign) |
| Detailed symptom description (patient carries a list) | Absence of details when describing symptoms |
| Patient answers multi-faceted questions | Patient only answers unambiguous questions |
| Patient is able to pinpoint the exact moment of onset | Patient is able to pinpoint the exact moment of onset – Patient has trouble pinpointing the exact moment of onset |
| Instable course of disorder | Progressive course of disorder |
The review’s authors believe that a diagnostic error resulting in a diagnosis of mild cognitive disability, rather than functional cognitive disorder, can cause iatrogenic harm to patients. It is not easy receiving the news that you may be developing dementia. When treating functional cognitive disorders, a positive approach appears essential, as it is with other functional neurological symptom disorders. For instance, it is better to not just rule out somatic explanations, but explain to the patient what IS actually there. Furthermore, it is important to discuss the possibility of recovery. Lastly, the ways in which the patient can regain control over his cognitive functioning need to be investigated. The approach will quite likely differ from other functional neurological symptom disorders, as cognitive problems interfere with the treatment process (e.g., remembering what was discussed, planning homework, etc.).
Source
McWhirter L,, Ritchie C, Stone J, Carson A. Functional cognitive disorders: a systematic review. Lancet Psychiatry. 2019 Nov 12.
