Affiliations: [a] Department of Neurology, Alzheimer’s Disease Center, Qianfoshan Hospital affiliated to Shandong University, Jinan, Shandong, PRC | [b] Department of Neurology, Shandong Provincial Hospital, Jinan, Shandong, PRC | [c] Department of Biological Sciences, the University of Texas, Dallas, Richardson, TX, USA
Correspondence:
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Correspondence to: Heng Du, MD, PhD, Assistant Professor, Department of Biological Science, The University of Texas, Dallas, 800W Campbell Rd, Richardson, TX 75080, USA. Tel.: +1 972 883 3531; E-mail: heng.du@utdallas.edu.
Abstract: Ghrelin is a stomach-derived circulating hormone. In addition to its function as an orexigenic stimulant, the role of ghrelin in the consolidation of learning and memory has been implicated in recent years. However, the status of circulating acylated ghrelin (AG, that is, the functional form of ghrelin) in the symptomatic predementia stage of Alzheimer’s disease (AD) has rarely been investigated. In the current study, we examined the serum levels of acylated and total ghrelin in 22 patients with mild cognitive impairment (MCI) and 30 cognitively normal controls. We have found that patients with MCI had significantly increased serum AG levels, which were inversely associated with defected short- and long-term memory as well as language skills. Of note, the levels of total circulating ghrelin were similar between the two groups. Intriguingly, serum AG but not total ghrelin was associated with AD risk factors including the age, hypertension, and hyperlipidemia. Therefore, circulating AG may serve as a potential early systemic biomarker for AD-related cognitive impairments. Nevertheless, the simplest interpretation of the results is that the levels of circulating AG are associated with cognitive impairments in patients with MCI, thereby forming the groundwork for our future studies on the systemic mechanisms of AD pertaining to the ghrelin system.
