Diagnostic utility of the Structured Inventory of Malingered Symptomatology (SIMS) in detecting feigned cognitive impairment in older adults.

OBJECTIVE

The primary aim of this study was to evaluate the diagnostic utility of the Structured Inventory of Malingered Symptomatology (SIMS) in detecting feigned cognitive impairment, specifically through self-reported cognitive and neurological symptoms, among older adults.

METHOD: The study was carried out at the University Hospital Kralovske Vinohrady in Prague, Czech Republic. The study included 172 participants: 56 patients with cognitive impairment (33 patients with MCI and 23 patients with dementia), 54 healthy elderly volunteers as a simulation group, and 62 healthy elderly honest responders. SIMS was used as the primary research tool. Cognitive performance was evaluated using the RBANS and the MoCA. Emotional status and functional abilities were measured using the GDS-15, BAI, and FAQ.

RESULTS

Our results support the utility of SIMS in older adults, as the instrument significantly distinguished feigned symptoms from genuine cognitive impairment. At the proposed cutoff score of > 20, the SIMS Total Score yielded 100% sensitivity and specificity. For the AM scale, sensitivity reached 89% and specificity 98% (cutoff > 7), while the NI scale achieved 87% sensitivity and 96% specificity (cutoff > 6). AUC values for these scales exceeded .959.

CONCLUSIONS

The primary contribution of this work is the introduction of revised cutoff scores specifically tailored for older adults (Total Score > 20, AM > 7, NI > 6, AF > 6, p > 2, and LI > 2). These adjusted criteria minimize the risk of false-positive results while extending the potential applications of SIMS within both clinical and forensic settings.