Delayed niacin skin flush response identifies cognitive impairment in late-life depression

This research aimed to inspect the discriminative and predictive utility of the niacin skin flush response (NSFR) in patients with late-life depression (LLD) with cognitive impairment (CI).

This study consisted of 86 LLD patients (46 with CI and 40 without CI), along with 22 Alzheimer's disease (AD) patients and 32 healthy elderly controls (HCs) as positive and negative controls, respectively. A subset of 74 LLD patients were reassessed after six months. The Montreal Cognitive Assessment (MoCA) was administered to assess cognitive capabilities. NSFR tests were performed using a modified protocol. Group differences in NSFR and clinical parameters were examined using multivariate ANOVA analysis. Model performance was evaluated using receiver operating characteristic (ROC) curves derived from NSFR measurements.

NSFR showed a significant inverse correlation with cognitive functions in LLD patients (R = -0.456, P < .001). Moreover, the parameter logEC₅₀, which quantifies the NSFR rate, was elevated in the LLD with CI group. LogEC₅₀ had an AUC of 0.767 (95 % CI: 0.667-0.867) in distinguishing LLD with CI from those without CI, which increased to 0.961 (95%CI:0.925-0.998) when combined with C- reactive protein. The predictive capacity of the baseline logEC₅₀ for cognitive prognosis (decline versus preservation) in LLD patients was statistically significant (AUC = 0.826, 95 % CI 0.731-0.921), which increased to 0.857 (95%CI:0.775-0.941) when combined with baseline MoCA.

A delayed NSFR represents a promising biomarker for identifying CI and predicting cognitive trajectories in patients with LLD. This study elucidates a novel methodology for the precise identification and prognostic evaluation of CI in LLD.