Effects of cholinesterase inhibitor on brain activation in Alzheimer’s patients measured with functional near-infrared spectroscopy
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Neurobiological effects of neuropsychiatric medication can contribute to the understanding of mechanisms of action and to the evaluation of target medication effects. Cholinesterase inhibitors (ChEI) have been used in patients with Alzheimer’s disease (AD) for years with only small knowledge about the underlying neurobiological effects. The measurement of brain activation links neurobiological and functional aspects but is challenging in the group of demented patients; here, an alternative method, functional near-infrared spectroscopy (fNIRS), is introduced to measure those medication effects.
The current study investigated the influence of ChEI on cortical activation of patients with AD measured using fNIRS during a verbal fluency task (VFT).
In this study, 24 probable AD patients were investigated three times using fNIRS: before medication with rivastigmine was given (t0), when the medication was at the target dose after 4 weeks (t1), and after the target dose was kept constant for a further 8 weeks (t2).
The results show a concentration increase of oxygenated hemoglobin as measured with fNIRS from t0 to t2 in speech relevant areas and a general decrease in prefrontal areas. Behaviorally, an improvement was found for the VFT used to measure cortical activation during fNIRS. In the neuropsychological test battery, no significant changes were found, yet high effect sizes for the mini mental status examination, immediate and delayed word list recall were found.
The results indicate a positive effect of ChEI on cognitive function. The underlying cortical changes can be imaged using fNIRS.
KeywordsFunctional near-infrared spectroscopy Alzheimer’s dementia Medication against dementia Rivastigmine patch Cholinesterase inhibitors
Compliance with Ethical Standards
The study was reviewed and approved by the ethics committee of the University of Tuebingen, and all procedures involved were in accordance with the latest version of the Declaration of Helsinki.
Prior to inclusion, written informed consent after receiving detailed information about the study procedure was obtained from the patients.
Conflict of interest
The authors declare that they have no competing interests.
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