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Alzheimer’s disease is characterized by the progressive deterioration of cognitive abilities particularly working memory while mild cognitive impairment (MCI) represents its prodrome. It is generally believed that neural compensation is intact in MCI but absent in Alzheimer’s disease. This study investigated the effects of increasing task load as a means to induce neural compensation through a novel visual working memory (VSWM) task using functional near-infrared spectroscopy (fNIRS). The bilateral prefrontal cortex (PFC) was explored due to its relevance in VSWM and neural compensation. A total of 31 healthy controls (HC), 12 patients with MCI and 18 patients with mild Alzheimer’s disease (mAD) were recruited. Although all groups showed sensitivity in terms of behavioral performance (i.e. score) towards increasing task load (level 1 to 3), only in MCI load effect on cortical response (as measured by fNIRS) was significant. At lower task load, bilateral PFC activation did not differ between MCI and HC. Neural compensation in the form of hyperactivation was only noticeable in MCI with a moderate task load. Lack of hyperactivation in mAD, coupled with significantly poorer task performance across task loads, suggested the inability to compensate due to a greater degree of neurodegeneration. Our findings provided an insight into the interaction of cognitive load theory and neural compensatory mechanisms. The experiment results demonstrated the feasibility of inducing neural compensation with the proposed VSWM task at the right amount of cognitive load. This may provide a promising avenue to develop an effective cognitive training and rehabilitation for dementia population. [ABSTRACT FROM AUTHOR]

Background: Cognitive performance is relatively well preserved during early cognitive impairment owing to compensatory mechanisms. Methods: We explored functional near-infrared spectroscopy (fNIRS) alongside a semantic verbal fluency task (SVFT) to investigate any compensation exhibited by the prefrontal cortex (PFC) in Mild Cognitive Impairment (MCI) and mild Alzheimer's disease (AD). In addition, a group of healthy controls (HC) was studied. A total of 61 volunteers (31 HC, 12 patients with MCI and 18 patients with mild AD) took part in the present study. Results: Although not statistically significant, MCI exhibited a greater mean activation of both the right and left PFC, followed by HC and mild AD. Analysis showed that in the left PFC, the time taken for HC to achieve the activation level was shorter than MCI and mild AD ( p = 0.0047 and 0.0498, respectively); in the right PFC, mild AD took a longer time to achieve the activation level than HC and MCI ( p = 0.0469 and 0.0335, respectively); in the right PFC, HC, and MCI demonstrated a steeper slope compared to mild AD ( p = 0.0432 and 0. 0107, respectively). The results were, however, not significant when corrected by the Bonferroni-Holm method. There was also found to be a moderately positive correlation ( R = 0.5886) between the oxygenation levels in the left PFC and a clinical measure [Mini-Mental State Examination (MMSE) score] in MCI subjects uniquely. Discussion: The hyperactivation in MCI coupled with a better SVFT performance may suggest neural compensation, although it is not known to what degree hyperactivation manifests as a potential indicator of compensatory mechanisms. However, hypoactivation plus a poorer SVFT performance in mild AD might indicate an inability to compensate due to the degree of structural impairment. Conclusion: Consistent with the scaffolding theory of aging and cognition, the task-elicited hyperactivation in MCI might reflect the presence of compensatory mechanisms and hypoactivation in mild AD could reflect an inability to compensate. Future studies will investigate the fNIRS parameters with a larger sample size, and their validity as prognostic biomarkers of neurodegeneration.

Objective: The objective of the study was to compare the effectiveness of bedside test kits for pIGFBP-1 and fetal fibronectin test in predicting preterm delivery., Materials and Methods: Patients presenting with symptoms of preterm labour between 24 and 34 weeks of gestation were recruited. Both pIGFBP-1 and fetal fibronectin bedside tests were performed. Managing obstetricians and patients were blinded to the pIGFBP-1 and fetal fibronectin results. Tocolysis and steroid therapy were administered to all the recruited patients. Outcome data were collected after delivery., Results: One hundred and eight patients were recruited into the study. Fourteen patients had to be excluded from the final analysis due to incomplete data and failure to meet inclusion criteria. Ninety-four patients had complete data for analysis. Among those with negative pIGFBP-1 and fetal fibronectin results, the median [+/-standard deviation (SD)] gestational age at delivery was 37.4 weeks (+/-2.8 weeks) and 37.4 weeks (+/-2.1 weeks), respectively. Among those with positive pIGFBP-1 and fetal fibronectin results, the median (+/-SD) gestational age at delivery was 32.9 weeks (+/-4.0 weeks) and 34.2 weeks (+/-4.2 weeks), respectively (P <0.001 for both pIGFBP-1 and fetal fibronectin). A positive result with either test was associated with a significantly reduced admission-to-delivery interval. The median admission-to-delivery interval was 2.8 weeks shorter in the group with positive pIGFBP-1 results compared to those with a negative pIGFBP-1 result (2.3 weeks compared with 5.1 weeks) (P <0.001). This is 1.8 weeks shorter in the group with positive fibronectin results, compared to those with a negative result (3.3 weeks compared with 5.1 weeks) (P=0.002). Both pIGFBP-1 and fetal fibronectin tests have high negative predictive value (NPV) in predicting risk of delivery within 48 hours, 7, or 14 days (1.00; 0.92; 0.92 and 0.97; 0.89; 0.89, respectively)., Conclusions: Both pIGFBP-1 and fetal fibronectin tests are effective adjuvant bedside test kits for the prediction of preterm delivery in patients presenting with signs or symptoms of preterm labour. pIGFBP-1 has the higher NPV of 1.00 in predicting risk of delivery within 48 hours.