Availability of reliable prognostic biomarkers that are also able to monitor preventive/therapeutic interventions in patients with mild cognitive impairment (MCI) is crucial. Cerebral brain-derived neurotrophic factor (BDNF) alterations were evidenced in Alzheimer's disease, but the value of blood BDNF in MCI is unclear, especially because of the incomplete/incorrect management of the numerous confounding factors unrelated to the disease. This study, applying a multidisciplinary methodological approach, aimed at clarifying whether blood BDNF can really mirror the cognitive symptoms of MCI, thus supporting the evaluation of clinical protocols' effectiveness as well as the definition of the conversion rate to dementia. Healthy elderly subjects (HE) and MCI patients were assessed for sociodemographic, neuropsychological, pharmacological, and lifestyle data, and plasma BDNF was measured (baseline); then, in the MCI cohort, the biomarker was tested in a comprehensive cognitive stimulation intervention (CS) as well as in a 2-year follow-up period. Plasma BDNF, cleansed from all the interfering factors, (1) did not discriminate HE and MCI patients; (2) in MCI patients reflected mood, social engagement, and subjective memory complaints but not cognition; (3) changed due to CS, although with no correlations to cognitive performances; and (4) predicted no functional deterioration. Our data indicate that the possible biased use of plasma BDNF in MCI is critically risky.

中文翻译：

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血脑源性神经营养因子是监测轻度认知障碍患者的有用生物标志物吗？

能够监测轻度认知障碍 (MCI) 患者的预防/治疗干预的可靠预后生物标志物的可用性至关重要。脑源性神经营养因子 (BDNF) 改变在阿尔茨海默病中得到证实，但血液 BDNF 在 MCI 中的价值尚不清楚，尤其是由于对与疾病无关的众多混杂因素的不完整/不正确管理。本研究采用多学科方法论，旨在阐明血液 BDNF 是否能真正反映 MCI 的认知症状，从而支持临床方案有效性的评估以及痴呆转化率的定义。对健康的老年受试者 (HE) 和 MCI 患者进行了社会人口学、神经心理学、药理学、和生活方式数据，并测量血浆 BDNF（基线）；然后，在 MCI 队列中，生物标志物在综合认知刺激干预 (CS) 以及 2 年的随访期间进行了测试。血浆 BDNF，清除了所有干扰因素，(1) 不区分 HE 和 MCI 患者；(2) MCI 患者反映情绪、社会参与和主观记忆抱怨，但不反映认知；(3) 由于 CS 而改变，尽管与认知表现没有相关性；(4) 预测没有功能恶化。我们的数据表明，在 MCI 中可能有偏见地使用血浆 BDNF 是非常危险的。清除所有干扰因素，（1）不区分HE和MCI患者；(2) MCI 患者反映情绪、社会参与和主观记忆抱怨，但不反映认知；(3) 由于 CS 而改变，尽管与认知表现没有相关性；(4) 预测没有功能恶化。我们的数据表明，在 MCI 中可能有偏见地使用血浆 BDNF 是非常危险的。清除所有干扰因素，（1）不区分HE和MCI患者；(2) MCI 患者反映情绪、社会参与和主观记忆抱怨，但不反映认知；(3) 由于 CS 而改变，尽管与认知表现没有相关性；(4) 预测没有功能恶化。我们的数据表明，在 MCI 中可能有偏见地使用血浆 BDNF 是非常危险的。