Arto Nordlund

Intra-individual stability of CSF biomarkers for Alzheimer's disease over two years.

This study examines the intra-individual stability of cerebrospinal fluid (CSF) biomarkers for Alzheimers disease (AD) over 2 years in 83 patients with mild cognitive impairment (MCI) and 17 cognitively healthy control individuals. All participants underwent clinical and neuropsychological evaluation and lumbar puncture at baseline and after 2 years at a university hospital memory clinic. CSF was analyzed for total tau (T-tau), phospho-tau(181) (P-tau(181)) and amyloid-beta(1-42) (Abeta(1-42)). During the 2-year observational time, 12 MCI patients progressed to AD and 3 progressed to vascular dementia, while 68 remained stable. Baseline T-tau and P-tau(181) levels were elevated in the MCI-AD group as compared to the stable MCI patients and the control group (p<0.01), while baseline Abeta(1-42) levels were lower (p<0.001). Stable MCI patients were biochemically indistinguishable from controls. The biomarker levels at baseline and after 2 years showed Pearson R values between 0.81 and 0.91 (p<0.001) and coefficients of variation of 7.2 to 8.7%. In conclusion, intra-individual biomarker levels are remarkably stable over 2 years. Thus, even minor biochemical changes induced by treatment against AD should be detectable using these biomarkers, which bodes well for their usefulness as surrogate markers for drug efficacy in clinical trials.

Prevalence and prognosis of Alzheimer's disease at the mild cognitive impairment stage.

Three sets of research criteria are available for diagnosis of Alzheimers disease in subjects with mild cognitive impairment: the International Working Group-1, International Working Group-2, and National Institute of Aging-Alzheimer Association criteria. We compared the prevalence and prognosis of Alzheimers disease at the mild cognitive impairment stage according to these criteria. Subjects with mild cognitive impairment (n = 1607), 766 of whom had both amyloid and neuronal injury markers, were recruited from 13 cohorts. We used cognitive test performance and available biomarkers to classify subjects as prodromal Alzheimers disease according to International Working Group-1 and International Working Group-2 criteria and in the high Alzheimers disease likelihood group, conflicting biomarker groups (isolated amyloid pathology or suspected non-Alzheimer pathophysiology), and low Alzheimers disease likelihood group according to the National Institute of Ageing-Alzheimer Association criteria. Outcome measures were the proportion of subjects with Alzheimers disease at the mild cognitive impairment stage and progression to Alzheimers disease-type dementia. We performed survival analyses using Cox proportional hazards models. According to the International Working Group-1 criteria, 850 (53%) subjects had prodromal Alzheimers disease. Their 3-year progression rate to Alzheimers disease-type dementia was 50% compared to 21% for subjects without prodromal Alzheimers disease. According to the International Working Group-2 criteria, 308 (40%) subjects had prodromal Alzheimers disease. Their 3-year progression rate to Alzheimers disease-type dementia was 61% compared to 22% for subjects without prodromal Alzheimers disease. According to the National Institute of Ageing-Alzheimer Association criteria, 353 (46%) subjects were in the high Alzheimers disease likelihood group, 49 (6%) in the isolated amyloid pathology group, 220 (29%) in the suspected non-Alzheimer pathophysiology group, and 144 (19%) in the low Alzheimers disease likelihood group. The 3-year progression rate to Alzheimers disease-type dementia was 59% in the high Alzheimers disease likelihood group, 22% in the isolated amyloid pathology group, 24% in the suspected non-Alzheimer pathophysiology group, and 5% in the low Alzheimers disease likelihood group. Our findings support the use of the proposed research criteria to identify Alzheimers disease at the mild cognitive impairment stage. In clinical settings, the use of both amyloid and neuronal injury markers as proposed by the National Institute of Ageing-Alzheimer Association criteria offers the most accurate prognosis. For clinical trials, selection of subjects in the National Institute of Ageing-Alzheimer Association high Alzheimers disease likelihood group or the International Working Group-2 prodromal Alzheimers disease group could be considered.

Cognitive impairment in patients with stress-related exhaustion

Patients who seek medical care for stress-related mental health problems frequently report cognitive impairments as the most pronounced symptom. The purpose of the present study was to compare cognitive function in patients with stress-related exhaustion with that in healthy controls, using a comprehensive battery of cognitive tests. We also explored whether neuropsychological findings were related to severity of illness measured using the Shirom–Melamed burnout questionnaire and hospital anxiety and depression scale. Thirty-three patients (15 males) and 37 healthy controls (11 males), mean age 46 years [standard deviation (SD) 3.9] and 47 years (SD 4.3), respectively, were included in the final analysis. Five cognitive domains were assessed: (1) speed, attention and working memory, (2) learning and episodic memory, (3) executive functions, (4) visuospatial functions and (5) language. The most pronounced difference between patients and controls was seen on executive function, when tested with a multidimensional test, including aspects of speed, control and working memory. The patients also performed poorer on Digit span, measuring attention span and working memory as well as on learning and episodic memory, when measured as delayed recall and the difference between immediate and delayed recall. Delayed recall was the only test that was significantly related to severity of burnout symptoms among the patients. This could reflect poor cognitive sustainability in the patients with the highest burnout scores, as this particular test was the last one performed during the test session. This study clearly shows that cognitive impairment should be considered when evaluating and treating patients who seek medical care for stress-related exhaustion.

Cognitive profiles of incipient dementia in the Goteborg MCI study.

Objective: To study which cognitive profiles of incipient dementia strongest predict the conversion to Alzheimer’s disease (AD) and mixed dementia (MD)/vascular dementia (VaD). Methods: 260 subjects with mild cognitive impairment (MCI) were included in the study and 209 (79%) were followed up after 2 years. At baseline, the subjects were assessed with a neuropsychological battery covering the cognitive domains speed/attention, memory, visuospatial, language and executive functions. Results: After 2 years, 9 subjects were considered normal, 148 had stationary MCI and 47 (23%) had converted to dementia. Twenty subjects were diagnosed with AD, 15 with MD and 9 with VaD. The others were 2 with unspecified dementias and 1 with primary progressive aphasia. Dementia converters had a high proportion of impairment in all cognitive domains. The profiles of incipient AD and MD/VaD differed, with memory, visuospatial and language symptoms preceding AD, and executive and speed/attention symptoms preceding MD/VaD. Conclusions: The risk of converting to dementia is increased when domains in addition to memory are impaired. The incipient AD and MD/VaD profiles differed quite clearly. Considering that the vascular group consisted of a majority of patients with MD, the differences are convincing – vascular disease seems to have an essential impact on cognition.

Increased Saliva Cortisol Awakening Response in Patients with Mild Cognitive Impairment

Background: It is unknown whether HPA-axis dysfunction is present in patients with mild cognitive impairment (MCI). The aim of the present study was to investigate whether cortisol levels are elevated among patients with MCI and/or whether the individuals have adequate feedback control of their HPA axis. Material and Methods: 27 patients with MCI and 15 healthy controls were included in the study. Saliva samplings were performed 5 times a day before intake of 0.5 mg dexamethasone, and 5 times a day after intake of dexamethasone, respectively. Results: Significantly higher cortisol levels were found 15 min after awakening among patients with MCI in comparison with the controls, both before and after dexamethasone administration (p < 0.05). Also, the ratio between cortisol at awakening time and 15 min after awakening was lower in the patient group after dexamethasone administration (p < 0.05). There were no significant differences in basal cortisol levels before or after dexamethasone between groups. Conclusion: The results indicate that there is an HPA-axis disturbance, with normal basal cortisol levels and increased awakening response among patients with MCI. The dissociation between basal values and the awakening response may be of pathophysiological importance for the cognitive impairment.

A Combination of Neuropsychological, Neuroimaging, and Cerebrospinal Fluid Markers Predicts Conversion from Mild Cognitive Impairment to Dementia

BACKGROUND Mild cognitive impairment (MCI) is a condition with increased risk for further cognitive decline. A considerable challenge lies in predicting which patients will eventually convert to dementia. OBJECTIVE To study prediction of dementia in MCI using neuropsychological tests, commonly used cerebrospinal fluid (CSF) biomarkers, and hippocampal volume. METHODS Twenty-one MCI patients converting to dementia, 21 stable MCI patients, and 26 controls were included in the study with a follow-up time of two years. The study participants underwent comprehensive examinations at inclusion: a neuropsychological assessment comprising 20 tests, MRI scanning with subsequent hippocampal volumetry, and CSF analyses of T-tau, P-tau, and Aβ42. RESULTS Neuropsychological tests, hippocampal volume, and the CSF markers Aβ42, P-tau, and T-tau all predicted conversion from MCI to dementia. A combination of all classes of markers was the most successful at predicting dementia (AUC 0.96) with a memory test (RAVLT) as the best individual predictor (AUC 0.93). Similar findings are reported for the prediction of Alzheimers disease. CONCLUSION Neuropsychological tests were the best individual predictors of dementia. A combination of markers improved the predictive ability with the combination of neuropsychological tests, CSF, and hippocampal volume as the best predictors of dementia.

Biomarkers in relation to cognitive reserve in patients with mild cognitive impairment--proof of concept.

Background: The concept of the cognitive reserve (CR) posits that factors such as education enable compensation for the effect of brain pathology. Consequently, pathology should be more pronounced in individuals with higher CR before becoming clinically apparent. Biomarkers such as total tau (t-tau) and β-amyloid 42 (Aβ42) may be surrogates for pathology in relation to CR in patients with neurodegenerative disease. Objective: To examine the applicability of biomarkers as surrogates for pathology in relation to the CR in patients with mild cognitive impairment (MCI) either converting to dementia or remaining stable at follow-up. Method: Comparisons of baseline t-tau, Aβ42, educational years and global cognition for MCI patients either converting to dementia (n = 57) or remaining stable (n = 91) were made. Patients converting to dementia were grouped on the basis of educational level and compared considering biomarkers and neuropsychological tests. Results: Stable MCI patients were better educated, performed better cognitively, had higher Aβ42 levels and lower levels of t-tau. Converting MCI patients with higher education had lower levels of Aβ42 and performed equally in neuropsychological tests compared to those with lower education. Conclusion: Our results suggest that highly educated MCI patients subsequently converting to dementia display more amyloid pathology.

Subcortical vascular dementia biomarker pattern in mild cognitive impairment.

Background: Mild cognitive impairment (MCI) is an etiologically unclear disorder. Cerebrospinal fluid (CSF) biomarkers are potentially useful for the differentiation between various MCI etiologies. Aim: The aim of the study was to assess whether baseline CSF hyperphosphorylated tau (P-tau), total tau (T-tau), amyloid β 1–42 (Aβ42) and neurofilament light (NF-L) in patients with MCI could predict subcortical vascular dementia (SVD) and Alzheimer’s disease (AD) at follow-up. Methods: Biomarker levels were assessed by Luminex xMAP technology and ELISA. Results: Increased baseline concentrations of NF-L significantly separated MCI-SVD from stable MCI. The MCI-SVD patients were inseparable from stable MCI but separable from patients developing AD (MCI-AD) on the basis of Aβ42, T-tau and P-tau181 levels. Conclusion: A combination of the biomarkers Aβ42, T-tau, P-tau181 and NF-L has the potential to improve the clinical separation of MCI-SVD patients from stable MCI and MCI-AD patients.

Multimodal prediction of dementia with up to 10 years follow up: the Gothenburg MCI study.

BACKGROUND Neuropsychological tests, CSF Aβ42, T-tau, P-tau181, hippocampal volume, and white matter lesions have been shown to predict conversion to dementia in patients with mild cognitive impairment (MCI). OBJECTIVE To examine the predictive value of combinations of these markers and to examine if the absence of pathological markers provides a lasting reduction of conversion rates. METHODS The Gothenburg MCI study is a clinically based study. Seventy-three MCI patients were included in the present sub-study and followed for a maximum of ten years. Thirty-four patients converted to dementia (18 to AD) and 39 remained stable. At inclusion, patients were classified into positive or negative risk groups according to results from neuropsychological testing (Rey auditory verbal learning test, Boston naming test, Trail making test B), CSF biomarkers (amyloid β42, T-tau, and P-tau181), and MRI scans (hippocampal volume, white matter lesions). RESULTS Trail making test B (TMT-B) was the best single predictor for the prediction of dementia (AUC 0.89, HR 25), and T-tau was the best predictor of AD (AUC 0.97, HR 41). The combination of hippocampal volume and TMT-B was the best combination for the prediction of dementia (HR 25), and the combination of hippocampal volume and T-tau was the best combination for the prediction of AD (HR 37). CONCLUSION Neuropsychological tests, CSF markers, and hippocampal volume predicted conversion from MCI to AD and general dementia. The absence of pathological markers provided a long-time protection from dementia.

Thyroid hormones are associated with poorer cognition in mild cognitive impairment.

Background: Alterations in interrelated endocrine axes may be related to the pathogenesis of mild cognitive impairment (MCI) and dementia. Methods: Salivary cortisol before and after a 0.5-mg dexamethasone test, and serum levels of thyroid-stimulating hormone, total thyroxine (T4), free T4, total triiodothyronine (TT3), estradiol, testosterone and insulin-like growth factor 1 were measured in 43 MCI cases and 26 healthy controls. All participants underwent a comprehensive neuropsychological test battery covering the cognitive domains of speed/attention, memory, visuospatial functions, language and executive functions. Results: The MCI group did not differ in basal levels of endocrine markers compared to controls. Among those with MCI, TT3 levels were inversely associated with cognitive performance across all domains. After stratifying MCI cases according to TT3 levels, those with relatively high TT3 levels showed impairment in memory as well as in visuospatial and executive functions. Those with TT3 levels at or below the lower boundary of the normal range performed comparably to healthy controls. Other endocrine markers were not related to cognitive performance. Conclusions: Among those with MCI, TT3 was associated with a neuropsychological profile typical of prodromal Alzheimer’s disease. While the mechanisms remain unclear, optimal levels of thyroid hormone under a compromising condition such as MCI and related neuropathology need reconsideration.