Dear editor,
We really appreciate Nicolini et al. for offering valuable information and discussion regarding the autonomic regulation and cognitive status. As mentioned in the “letter to the editor”, the authors observed that a higher sympathetic activation was related to cognitive decline whereas a greater parasympathetic HRV response predicted a lesser decline in executive functioning for MCI elderly [1]. Considering that the presence of cognitive impairment usually precedes the diagnosis of dementia, these results were compatible with our findings [2].
The authors further addressed that the central autonomic network (CAN) may be a potential influencer of cognitive decline or dementia through the brain-heart axis [1]. Previous study has demonstrated that CAN modulates the pathogenesis of essential hypertension or orthostatic hypotension [3], which were crucial in the occurrence of dementia [4]. Therefore, the modulation of CAN may help to further explain the possible impact of autonomic dysregulation on dementia risk.
However, the activity of individual units of CAN (e.g. the hippocampus, insula, locus coeruleus and prefrontal cortex) was not examined in our previous study [2]. Besides, the diagnostic information of dementia was obtained by ICD code from an established database, whereas the examine of cognitive impairment includes various validated questionnaires and scales, which were not available in our study [2]. In light of that the process of cognitive impairment and dementia might be insidious and may take many years for detecting the abnormality, we agree that further large prospective cohort studies using comprehensive evaluating tools for cognitive impairment and analyzing the cognitive test changes with time may be helpful to clarify the interaction between autonomic modulation and cognitive function. With regards to CAN and cognitive status, studies applying functional neuroimaging studies regarding activity of specific unit of CAN [5] may also be valuable for testifying the role of CAN in pathogenesis of cognitive impairment and dementia.
Footnotes
Peer review under responsibility of Chang Gung University.
Contributor Information
Jin-Shang Wu, Email: jins@mail.ncku.edu.tw.
Edward Chia-Cheng Lai, Email: edward_lai@mail.ncku.edu.tw.
References
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