Validation of two inventories for the diagnosis and monitoring of functional memory disorder

Abstract

Objective: Functional memory disorder (FMD) is an acquired nonorganic condition characterized by significant deficits of memory and concentration that occur in daily living and are thought to be caused by psychosocial burden and distress. FMD is an important differential diagnosis to organic mild cognitive impairment. Although frequent, FMD is under-researched and mostly diagnosed by exclusion rather than by positive diagnostic criteria. Diagnosis can be difficult in patients with borderline cognitive test results.

Methods: To aid in the clinical diagnosis and monitoring of FMD, a short 10-item FMD questionnaire and a 22-item FMD rating scale were developed. They asses a range of memory complaints thought to be indicative of FMD. Each of the two inventories was applied and evaluated in a separate study involving FMD patients and control groups. In one study, the natural course of FMD was observed. In the other study, the effect of a therapeutic intervention was assessed. Here, we present the full text of the two FMD inventories and data on test quality characteristics.

Results: Internal consistency and split-half-reliability indices were excellent throughout. At suitable cutoffs, both versions discriminated FMD patients from control subjects with high accuracy. Both also demonstrated discriminant construct validity. Moreover, the long version demonstrated high test-retest reliability and convergent construct validity and proved to be sensitive to change.

Conclusion: The short version of the FMD inventory is a helpful tool in the clinical diagnosis of FMD. The longer version is suitable for monitoring of FMD severity in the context of therapeutic interventions and observational studies. To determine whether the inventories can discriminate FMD from organic mild cognitive impairment, further studies are required.