Effect of Long-Term Benzodiazepines for Chronic Insomnia on Cognitive Function and Waking Electroencephalography: A Case-Control Study

OBJECTIVE: The relationship between benzodiazepine use and cognitive decline in insomnia patients has been reported, but still conflicting. Thus, we tried to determine whether long-term exposure of benzodiazepine might be associated with changes of cognition and electroencephalography (EEG) findings in patients with chronic insomnia. METHODS: Insomniacs using benzodiazepines (n=29), drug-free insomniacs (n=27), and age- and sex-matched controls (n=28) were recruited. Neurocognitive function tested with Korean version of the Consortium to Establish a Registry for Alzheimer’s Disease Assessment Packet Neuropsychological Assessment Battery, quantitative EEG in awake state, and information of benzodiazepine usage were obtained. RESULTS: Drug-free insomniacs reported more severe symptoms than insomniacs using benzodiazepine (p<0.001). Insomniacs using benzodiazepine showed a decrease of executive function in Trail Making Test A than drug-free insomniacs and controls (0.73±0.66 vs. 1.27±0.38 vs. 1.09±0.47, p<0.001) and in categorical fluency than drug-free insomniacs (-0.01±0.99 vs. 1.26±0.97, p=0.002). However, such decrease of executive function was not proportional to daily dose or cumulative dose of benzodiazepine. The EEG was not significantly different between insomniacs using benzodiazepine and drug-free insomniacs, while EEG of insomniacs showed low relative theta power in frontal and parietal regions but high relative beta power in frontal region than that of controls. CONCLUSION: Benzodiazepine users with chronic insomnia showed an impairment of executive function compared to drug-free insomniacs and controls although they showed relatively decreased severity of insomnia symptoms. Chronic insomniacs showed a hyper-arousal manifestation in front-parietal region of brain regardless of benzodiazepine exposure.