The syndrome of functional memory disorder: definition, etiology, and natural course.

OBJECTIVES: Nonorganic, functional memory disorder (FMD) is frequent in memory clinic patients, and is an important differential diagnosis to prodromal dementia. The authors propose a definition of FMD as an acquired medical and psychological condition that is closely related to psychosocial burden and distress.

DESIGN: Prospective follow-up study, aimed to evaluate the natural course of FMD.

SETTING: University hospital memory clinic.

PARTICIPANTS: Seventy-three patients who suffered memory deficits and psychological distress and had normal test results. Forty-six attended a follow-up examination after a mean delay of 20.1 months.

MEASUREMENTS: FMD severity was assessed with a structured inventory and an overall self-rating scale. Objective performance was assessed by standardized tests of memory and attention.

RESULTS: Identified causes of distress were overwork, interpersonal conflicts, somatic illness, adjustment disorder, dysthymia, and Alzheimer phobia. At follow-up, FMD had resolved in only six patients, and persisted in 39. Average symptom severity showed only a minor reduction.

CONCLUSION: FMD is, in many instances, a long-term rather than transient problem. Possible reasons include the persistence of burden factors and the failure to evade the "stress spiral" of mutual reinforcement of distress and cognitive dysfunction.