Odor Identification Moderates Relationship Between Cognitive Training and Cognitive Decline

Abstract

AbstractBackgroundOlfactory deficits have been shown to predict cognitive decline. Recent findings suggest that computerized cognitive training may reduce the risk of cognitive decline and dementia. However, the impact of olfaction deficits on cognitive training outcomes is unclear. In this study, we investigate how lower odor identification may moderate the relationship between treatment assignment (cognitive games versus crossword puzzles) and cognitive outcomes in older adults diagnosed with mild cognitive impairment (MCI).MethodData were drawn from the Cognitive Training and Neuroplasticity in Mild Cognitive Impairment (COG‐IT) Trial (NCT03205709). In this two‐site, single‐blinded, 78‐week trial, participants with MCI — stratified by age, severity (early/late MCI), and site — were randomly assigned to 12 weeks of intensive, home‐based, Computerized Cognitive Training (CCT) or computerized Crossword Puzzle Training (CPT), followed by six booster sessions. 106 patients received neuropsychological and olfactory assessments through the 11‐item Alzheimer’s Disease Assessment Scale–Cognitive Subscale (ADAS‐Cog) and the 40‐item University of Pennsylvania Smell Identification Test (UPSIT). In linear mixed‐model analyses, the effect of baseline UPSIT score on change in the ADAS‐Cog score from baseline over 78 weeks by treatment group, adjusted for age and baseline ADAS‐Cog, was assessed.ResultAmong 106 older adults (n = 50 [games]; n = 56 [crosswords]), higher baseline UPSIT scores predicted improved ADAS‐Cog performance at week 78 for all patients randomized to CPT (beta coefficient, 0.15, 95% confidence interval [CI], 0.02 to 0.27; P = 0.02). Greater baseline UPSIT score predicted improved ADAS‐Cog performance at weeks 12, 52, and 78 for early MCI patients randomized to CPT (Week 12: beta coef. 0.26, 95% CI 0.09 to 0.43; Week 52: beta coef. 0.23, 95% CI 0.05 to 0.40; Week 78: beta coef. 0.22, 95% CI 0.05 to 0.39). This was not shown in early MCI patients randomized to CCT. Higher baseline UPSIT predicted significant improvement in ADAS‐Cog for late MCI patients randomized to CCT at week 78 (beta coefficient, 0.24, 95% CI 0.05 to 0.42; P = 0.01).ConclusionOur results are consistent with literature, suggesting that impaired olfaction moderates memory decline. Our preliminary results show that individuals with less impaired olfaction may experience greater cognitive improvement following cognitive training.