Mild cognitive impairment and microbiota: what is known and future perspectives.

Mild cognitive impairment (MCI) is a heterogeneous condition definable as the intermediate clinical state between normal aging and dementia. As a pre-dementia condition, there is a recent growing interest in the identification of non-invasive markers able to predict the progression from MCI to a more advanced stage of the disease. Previous evidence showed the close link between gut microbiota and neurodegenerative diseases, such as Alzheimer's (AD) and Parkinson's disease (PD). Conversely, the actual relationship between gut microbiota and MCI is yet to be clarified. In this work, we provide an overview about the current knowledge regarding the role of gut microbiota in the context of MCI, also assessing the potential for microbiota-targeted therapies. Through the review of the most recent studies focusing on this topic, we found evidence of an increase of Bacteroidetes at phylum level and Bacteroides at genus level in MCI subjects with respect to healthy controls and patients with AD. Despite such initial evidence, the definitive identification of a typical microbiota profile associated with MCI is still far from being achieved. These preliminary results, however, are growingly encouraging research on the role of gut microbiota modulation in improving the cognitive status of pre-dementia subjects. To date, few studies evaluated the role of probiotics in MCI subjects, and they showed favorable results, although still biased by small sample size, heterogeneity of study design and short follow-up.

Diagnostic Accuracy of Fecal Calprotectin in Discriminating Organic-Inflammatory Gastrointestinal Diseases and Functional Gastrointestinal Disorders in Older Patients.

Fecal calprotectin (FC) has been largely recognized as a surrogate marker of intestinal neutrophilic inflammation, very reliable in distinguishing between inflammatory bowel diseases and functional gastrointestinal (GI) disorders. Aging has been suggested to influence FC results and their diagnostic accuracy; however, no studies are specifically targeted on this focus. In a retrospective study, we evaluated the eventual age-differences of the diagnostic accuracy of FC in discriminating between organic-inflammatory GI diseases and functional GI disorders. In 573 younger and 172 older (≥65 years) subjects undergoing an FC assay, we found that the latter showed higher median FC values, 72 (25-260) µg/g vs. 47 (25-165) µg/g (p < 0.01). Younger patients were more commonly affected by IBDs, while colorectal cancer and high-risk polyps, infective colitis, and diverticular disease represented the most common findings in the older subgroup. However, the estimated optimum FC threshold in discriminating between organic-inflammatory GI diseases and functional GI disorders was quite similar between the two groups (109 µg/g for the younger subgroup and 98 µg/g for the older subgroup), maintaining a very high specificity. In conclusion, we show that FC also represents a very specific test for intestinal inflammation in older patients, at similar threshold levels to younger subjects.