Associations of oral health status and swallowing function with cognitive impairment in the aging population: a cross-sectional study.

BACKGROUND: The purpose of this study was to investigate the relationships of oral health status and swallowing function with cognitive impairment in community-dwelling older adults from Changsha, Hunan Province, China. METHODS: In this cross-sectional study, we analyzed the data of 215 participants aged ≥ 50 years which were retrieved from the Xiangya and Panasonic mild cognitive impairment (MCI) Study, a community-based study conducted among the residents of the urban areas of Hunan province in China. Demographic information of all participants was collected. We determined oral function by evaluating oral hygiene, oral dryness, occlusal force, tongue pressure, chewing function, swallowing function, remaining teeth number, and other indicators. The mini-mental state examination (MMSE) was used to screen for cognitive function. The relationship between each oral function evaluation item and cognitive function was investigated using correlation analysis. The associations between oral health status and swallowing function with cognitive impairment were inferred using multiple regression analysis. RESULTS: The general characteristics of participants showed statistically significant correlation coefficients in number of teeth remaining (p = 0.003) and number of teeth lost (p < 0.0001). Almost half of the 25 participants (48%) were aged from 70-80 years. Only 25 older adults (11.6% of the participants) were determined to have cognitive impairment by MMSE sores less than 24. Tongue pressure in male participants was the only significant independent variable that was associated with cognitive impairment (p = 0.01971). The results indicate that male participants with lower MMSE scores had a relative deficiency in tongue pressure. CONCLUSIONS: In this cross-sectional study, the oral health status and swallowing function of participants were in relatively good condition and showed low correlations with cognitive impairment. However, lower tongue pressures were associated with lower MMSE scores in males, indicating it could serve as a novel oral function index for evaluating cognitive impairment.

Automatic Detection of Putative Mild Cognitive Impairment from Speech Acoustic Features in Mandarin-Speaking Elders.

BACKGROUND: To date, the reliable detection of mild cognitive impairment (MCI) remains a significant challenge for clinicians. Very few studies investigated the sensitivity of acoustic features in detecting Mandarin-speaking elders at risk for MCI, defined as "putative MCI" (pMCI). OBJECTIVE: This study sought to investigate the possibility of using automatically extracted speech acoustic features to detect elderly people with pMCI and reveal the potential acoustic markers of cognitive decline at an early stage. METHODS: Forty-one older adults with pMCI and 41 healthy elderly controls completed four reading tasks (syllable utterance, tongue twister, diadochokinesis, and short sentence reading), from which acoustic features were extracted automatically to train machine learning classifiers. Correlation analysis was employed to evaluate the relationship between classifier predictions and participants' cognitive ability measured by Mini-Mental State Examination 2. RESULTS: Classification results revealed that some temporal features (e.g., speech rate, utterance duration, and the number of silent pauses), spectral features (e.g., variability of F1 and F2), and energy features (e.g., SD of peak intensity and SD of intensity range) were effective predictors of pMCI. The best classification result was achieved in the Random Forest classifier (accuracy = 0.81, AUC = 0.81). Correlation analysis uncovered a strong negative correlation between participants' cognitive test scores and the probability estimates of pMCI in the Random Forest classifier, and a modest negative correlation in the Support Vector Machine classifier. CONCLUSIONS: The automatic acoustic analysis of speech could provide a promising non-invasive way to assess and monitor the early cognitive decline in Mandarin-speaking elders.

Rapid transneuronal destruction following peripheral nerve transection in the medullary dorsal horn is enhanced by strychnine, picrotoxin and bicuculline.

The effects of systemic administration of strychnine (1 mg/kg), picrotoxin (0.5 mg/kg) and bicuculline (2 mg/kg) on acute transsynaptic destruction of medullary dorsal horn neurons following transection of the inferior alveolar nerve were assessed in rats. Single intraperitoneal injections of the above drugs were given without, 1 min before or 1 min after the nerve transection. The effect of transection without drug administration was also examined. Eighteen hours after nerve transection without drug, approximately 7 dark neurons were found in a single toluidine blue stained 1 micron section of the rostral medullary dorsal horn ipsilateral to the nerve transection. Administration of the drugs 1 min before the nerve transection significantly increased the number of dark neurons in a single section to about 17 (strychnine), 46 (picrotoxin) and 20 (bicuculline). These dark neurons were found mainly in the dorsal half of medullary dorsal horn. Delivery of any of the drugs 1 min after the nerve transection did not increase the number of dark neurons. The data thus indicate that the transneuronal effect of transection of the nerve was enhanced by antagonism of glycinergic and GABAergic inhibition of dorsal horn neurons. In view of the short latency and duration of transsynaptic destructive activity, a massive injury discharge of primary afferent neurons and the subsequent release of excitatory neurotransmitters appear to be the direct cause of convulsant-enhanced rapid transsynaptic destruction which follows the peripheral nerve transection.

Topical application of colchicine, vinblastine and vincristine prevents strychnine-enhanced transsynaptic degeneration in the medullary dorsal horn following transection of the inferior alveolar nerve in adult rats.

The effect of topical application of axonal transport blockers to the transected peripheral nerve was assessed by quantitating the strychnine-enhanced transsynaptic degeneration following transection of the inferior alveolar nerve in adult rats. Systemic administration of strychnine (1 mg/kg/day) for 7 days at the postoperational interval of 23 days proved to be suitable for quantitating the transsynaptic degeneration at the light microscopic level. When the proximal stump of transected nerve was treated with 2% colchicine immediately after transection, 5.8 +/- 6.8 dark neurons in a single section of the medullary dorsal horn, ipsilateral to the nerve transection, were observed. Following similar treatment with 0.4% vinblastine and 0.2% vincristine, 24.4 +/- 10.5 and 9.4 +/- 7.0 dark neurons were seen, respectively. When compared with 43.0 +/- 9.4 dark neurons, which were seen in animals without alkaloid treatment, colchicine, vinblastine and vincristine significantly reduced the transsynaptic degeneration by 86, 43, and 78%, respectively. Possible mechanisms involved in prevention of transsynaptic degeneration by the alkaloids are discussed.