Functional (Psychogenic) Cognitive Disorders: A Perspective from the Neurology Clinic.

Cognitive symptoms such as poor memory and concentration represent a common cause of morbidity among patients presenting to general practitioners and may result in referral for a neurological opinion. In many cases, these symptoms do not relate to an underlying neurological disease or dementia. In this article we present a personal perspective on the differential diagnosis of cognitive symptoms in the neurology clinic, especially as this applies to patients who seek advice about memory problems but have no neurological disease process. These overlapping categories include the following 'functional' categories: 1) cognitive symptoms as part of anxiety or depression; 2) "normal" cognitive symptoms that become the focus of attention; 3) isolated functional cognitive disorder in which symptoms are outwith 'normal' but not explained by anxiety; 4) health anxiety about dementia; 5) cognitive symptoms as part of another functional disorder; and 6) retrograde dissociative (psychogenic) amnesia. Other 'non-dementia' diagnoses to consider in addition are 1) cognitive symptoms secondary to prescribed medication or substance misuse; 2) diseases other than dementia causing cognitive disorders; 3) patients who appear to have functional cognitive symptoms but then go on to develop dementia/another neurological disease; and finally 4) exaggeration/malingering. We discuss previous attempts to classify the problem of functional cognitive symptoms, the importance of making a positive diagnosis for the patient, and the need for large cohort studies to better define and manage this large group of patients.