Medical Symptom Validity Test (MSVT) profiles in individuals being evaluated for Alzheimer's disease

Objective:Our purpose was to determine whether Medical Symptom Validity Test (MSVT) profiles could differentiate performance invalidity from true impairment in patients with varying levels of memory impairment and functional ability being evaluated for Alzheimer's disease (AD). Method: Seventy-three older adults (13 healthy controls, 25 mild cognitive impairment [MCI], 16 mild AD, 19 moderate AD) were evaluated with a neuropsychological battery including the MSVT and activities of daily living (ADL) measures. Using MSVT classification guidelines, examinees' MSVT profiles were categorized as: 1) valid, 2) invalid, 3) weak memory, or 4) genuine memory impairment (GMIP). Results: Eighty-four percent of moderate AD examinees produced a GMIP. Among MCI and mild AD examinees, who had only modestly affected ADLs, a substantial proportion manifested a GMIP (40% and 62.5%, respectively). An invalid profile was uncommon across patient groups (12.5% in mild AD, 5.3% in moderate AD, and 0% in MCI). Conclusions: The MSVT functions reasonably well in a dementia sample to determine if an examinee has an invalid profile, although for mild AD examinees, the false positive rate is slightly above the recommended 10% cut-off. However, even individuals with MCI, mild AD and relative preservation of ADLs may manifest a GMIP, demonstrating that such profile is found across patients with lower and higher degrees of functional impairment. Given this finding, the usefulness of the GMIP in differentiating performance invalidity from true impairment in patients being evaluated for AD appears limited.