Postdoctoral Fellow Sanders-Brown Center on Aging, University of Kentucky Lexington, United States
Background: Although gabapentin has been increasingly prescribed to older adults, the relationship between gabapentin and neurocognitive changes is not well studied.
Objectives: This study aimed to examine the association of gabapentin use and neurocognitive changes (e.g., cognitive decline, functional status decline, and motor function change) in older adults with cognitive impairment.
Methods: A retrospective cohort study was conducted using the National Alzheimer’s Coordinating Center Uniform Data Set (2005-March 2022). Participants with cognitive impairment at the visit of gabapentin initiation (i.e., index visit) were included. Up to 9 non-users for each user were randomly selected using the incidence density sampling method. Cognitive decline was defined as any increase of Clinical Dementia Rating global score (CDRGLOB) and 1-point increase in Clinical Dementia Rating sum of boxes (CDRSUM). Functional status decline was defined as a 3-point increase in the Functional Activities Questionnaire (FAQ) sum and 0.3-point increase of mean of FAQ. Change in motor behavior was defined as new clinician reports of gait disorder, falls, and slowness. To mitigate confounding and selection bias, joint stabilized inverse probability of treatment weights and stabilized inverse probability of censoring weights were used. All analyses were conducted comparing index to index+1 and index+2 visits.
Results: We included 472 new-users (mean age [SD]: 78.8 [7.5]; male 45.3%) and 4,248 nonusers (79.2 [7.6]; 49.2%) with cognitive impairment at index. Gabapentin initiation was significantly associated with no decline on the CDRGLOB (odds ratio [95% confidence interval]: 0.71 [0.51, 0.99]) at index+1 visit. The association of gabapentin initiation with the other outcomes were not statistically significant. At index+1 visit, gabapentin initiation was associated with no decline on CDRSUM (0.82 [0.63, 1.06]), sum of FAQ (0.94 [0.65, 1.37]), and mean of FAQ (0.90 [0.68, 1.19]). Also, at index+2 visit, gabapentin initiation was associated with no decline on CDRGLOB (0.90 [0.63, 1.28]), CDRSUM (0.79 [0.57, 1.09]), sum of FAQ (0.88 [0.55, 1.41]), and mean of FAQ (0.83 [0.59, 1.16]). After excluding new-users with motor dysfunction (n=146) at index, we identified 326 new-users (78.3 [7.3]; 43.3%) and 2,934 nonusers (78.6 [7.3]; 47.4%); in this sample, gabapentin initiation was associated with increased odds of falls at the index+2 visit (2.37 [1.28, 4.38]).
Conclusions: Our study suggested that gabapentin use was associated with maintaining cognitive and functional status, and declining in motor function among older adults with cognitive impairment. Due to limitations of that data, further studies are needed to examine the risks and benefits of prescribing gabapentin in older adults.
