BackgroundA growing body of evidence suggests that the plasma concentration of the neurofilament light chain (NfL) might be considered a plasma biomarker for the screening of neurodegeneration in Alzheimer’s disease (AD).MethodsWith a single molecule array method (Simoa, Quanterix), plasma NfL concentrations were measured in 99 subjects with AD at the stage of mild cognitive impairment (MCI-AD; n = 25) or at the stage of early dementia (ADD; n = 33), and in nondemented controls (n = 41); in all patients, the clinical diagnoses were in accordance with the results of the four core cerebrospinal fluid (CSF) biomarkers (amyloid β (Aβ)1–42, Aβ42/40, Tau, and pTau181), interpreted according to the Erlangen Score algorithm. The influence of preanalytical storage procedures on the NfL in plasma was tested on samples exposed to six different conditions.ResultsNfL concentrations significantly increased in the samples exposed to more than one freezing/thawing cycle, and in those stored for 5 days at room temperature or at 4 °C. Compared with the control group of nondemented subjects (22.0 ± 12.4 pg/mL), the unadjusted plasma NfL concentration was highly significantly higher in the MCI-AD group (38.1 ± 15.9 pg/mL, p < 0.005) and even further elevated in the ADD group (49.1 ± 28.4 pg/mL; p < 0.001). A significant association between NfL and age (ρ = 0.65, p < 0.001) was observed; after correcting for age, the difference in NfL concentrations between AD and controls remained significant (p = 0.044). At the cutoff value of 25.7 pg/mL, unconditional sensitivity, specificity, and accuracy were 0.84, 0.78, and 0.82, respectively. Unadjusted correlation between plasma NfL and Mini Mental State Examination (MMSE) across all patients was moderate but significant (r = −0.49, p < 0.001). We observed an overall significant correlation between plasma NfL and the CSF biomarkers, but this correlation was not observed within the diagnostic groups.ConclusionsThis study confirms increased concentrations of plasma NfL in patients with Alzheimer’s disease compared with nondemented controls.
Chronically administered antidepressant drugs, particularly selective serotonin (5-HT) reuptake inhibitors (SSRIs), are clinically effective in the treatment of all anxiety disorders, while the clinical effectiveness of "traditional" anxiolytics, such as benzodiazepines (BDZs), is limited to generalised anxiety disorder or acute panic attacks. This implies that animal models of anxiety should be sensitive to SSRIs and other antidepressants in order to have predictive validity. We reviewed the literature on the effects of antidepressants in the so-called animal models of anxiety and found that only the isolation-induced calls in guinea-pig pups may reveal anxiolytic-like action of all antidepressant classes after acute administration. Some other models, such as marble-burying or conditioned-freezing behaviours, and isolation- or shock-induced ultrasonic vocalisation models, may detect anxiolytic-like activity of acutely administered antidepressants, although the sensitivity of these models is usually limited to SSRIs and other drugs affecting 5-HT uptake. The predictive validity of models of "anxiety", such as the plus-maze and light-dark transition tests or stress-induced hyperthermia, appears to be limited to BDZ-related drugs. Far less work has been done on chronic administration of antidepressants in animal anxiety models. Unless and until such studies have been undertaken, the true predictive value of the anxiety models will remain unknown.
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