Jan Marcusson

CSF Biomarkers and Incipient Alzheimer Disease in Patients With Mild Cognitive Impairment

CONTEXT Small single-center studies have shown that cerebrospinal fluid (CSF) biomarkers may be useful to identify incipient Alzheimer disease (AD) in patients with mild cognitive impairment (MCI), but large-scale multicenter studies have not been conducted. OBJECTIVE To determine the diagnostic accuracy of CSF beta-amyloid(1-42) (Abeta42), total tau protein (T-tau), and tau phosphorylated at position threonine 181 (P-tau) for predicting incipient AD in patients with MCI. DESIGN, SETTING, AND PARTICIPANTS The study had 2 parts: a cross-sectional study involving patients with AD and controls to identify cut points, followed by a prospective cohort study involving patients with MCI, conducted 1990-2007. A total of 750 individuals with MCI, 529 with AD, and 304 controls were recruited by 12 centers in Europe and the United States. Individuals with MCI were followed up for at least 2 years or until symptoms had progressed to clinical dementia. MAIN OUTCOME MEASURES Sensitivity, specificity, positive and negative likelihood ratios (LRs) of CSF Abeta42, T-tau, and P-tau for identifying incipient AD. RESULTS During follow-up, 271 participants with MCI were diagnosed with AD and 59 with other dementias. The Abeta42 assay in particular had considerable intersite variability. Patients who developed AD had lower median Abeta42 (356; range, 96-1075 ng/L) and higher P-tau (81; range, 15-183 ng/L) and T-tau (582; range, 83-2174 ng/L) levels than MCI patients who did not develop AD during follow-up (579; range, 121-1420 ng/L for Abeta42; 53; range, 15-163 ng/L for P-tau; and 294; range, 31-2483 ng/L for T-tau, P < .001). The area under the receiver operating characteristic curve was 0.78 (95% confidence interval [CI], 0.75-0.82) for Abeta42, 0.76 (95% CI, 0.72-0.80) for P-tau, and 0.79 (95% CI, 0.76-0.83) for T-tau. Cut-offs with sensitivity set to 85% were defined in the AD and control groups and tested in the MCI group, where the combination of Abeta42/P-tau ratio and T-tau identified incipient AD with a sensitivity of 83% (95% CI, 78%-88%), specificity 72% (95% CI, 68%-76%), positive LR, 3.0 (95% CI, 2.5-3.4), and negative LR, 0.24 (95% CI, 0.21-0.28). The positive predictive value was 62% and the negative predictive value was 88%. CONCLUSIONS This multicenter study found that CSF Abeta42, T-tau, and P-tau identify incipient AD with good accuracy, but less accurately than reported from single-center studies. Intersite assay variability highlights a need for standardization of analytical techniques and clinical procedures.

An In Vitro Model for Neuroscience: Differentiation of SH-SY5Y Cells into Cells with Morphological and Biochemical Characteristics of Mature Neurons

Neuroscience, including research on Alzheimers disease, is hampered by the lack of suitable in vitro models to study the human nervous system. To counteract this, many attempts to differentiate cell lines into more neuron-like cells have been performed, resulting in partial expression of neuronal features. Furthermore, it has been reported that neuroblastoma cell lines lack mature isoforms of tau. Our aim was to develop an improved in vitro model, generating sustainable cells with morphology and biochemistry of human, mature neurons. To obtain cells with neuronal differentiation and function, we investigated the effect of combining three-dimensional culturing of SH-SY5Y cells in extracellular matrix (ECM) gel with several factors reported to have neuro-differentiating effects. This resulted in cells with apparent neuronal morphology with long, extensively branched neurites. Further investigation revealed expression of several neurospecific markers including synapse protein Sv2 and nuclear marker NeuN, as well as the presence of synapses and axonal vesicle transport. In addition, these cells expressed mature tau isoforms, and tau protein expression was significantly increased compared to undifferentiated cells, reaching levels found in adult human brain. In conclusion, we found that pre-treatment with retinoic acid followed by ECM gel culturing in combination with brain derived neurotrophic factor, neuregulin beta1, nerve growth factor, and vitamin D3 treatment generated sustainable cells with unambiguous resemblance to adult neurons. These cells also expresses adult splicing forms of tau with neuronal localization, making this cellular in vitro model useful in many areas of neuroscience research, particularly the Alzheimers disease field.

The cerebrospinal fluid "Alzheimer profile": Easily said, but what does it mean?

We aimed to identify the most useful definition of the “cerebrospinal fluid Alzheimer profile,” based on amyloid‐ß1‐42 (Aβ42), total tau, and phosphorylated tau (p‐tau), for diagnosis and prognosis of Alzheimers disease (AD).

Spreading of Neurodegenerative Pathology via Neuron-to-Neuron Transmission of β-Amyloid

Alzheimers disease (AD) is the major cause of dementia. During the development of AD, neurofibrillary tangles progress in a fixed pattern, starting in the transentorhinal cortex followed by the hippocampus and cortical areas. In contrast, the deposition of β-amyloid (Aβ) plaques, which are the other histological hallmark of AD, does not follow the same strict spatiotemporal pattern, and it correlates poorly with cognitive decline. Instead, soluble Aβ oligomers have received increasing attention as probable inducers of pathogenesis. In this study, we use microinjections into electrophysiologically defined primary hippocampal rat neurons to demonstrate the direct neuron-to-neuron transfer of soluble oligomeric Aβ. Additional studies conducted in a human donor–acceptor cell model show that this Aβ transfer depends on direct cellular connections. As the transferred oligomers accumulate, acceptor cells gradually show beading of tubulin, a sign of neurite damage, and gradual endosomal leakage, a sign of cytotoxicity. These observations support that intracellular Aβ oligomers play a role in neurodegeneration, and they explain the manner in which Aβ can drive disease progression, even if the extracellular plaque load is poorly correlated with the degree of cognitive decline. Understanding this phenomenon sheds light on the pathophysiological mechanism of AD progression. Additional elucidation will help uncover the detailed mechanisms responsible for the manner in which AD progresses via anatomical connections and will facilitate the development of new strategies for stopping the progression of this incapacitating disease.

CSF-Biomarkers in Olympic Boxing: Diagnosis and Effects of Repetitive Head Trauma

Background Sports-related head trauma is common but still there is no established laboratory test used in the diagnostics of minimal or mild traumatic brain injuries. Further the effects of recurrent head trauma on brain injury markers are unknown. The purpose of this study was to investigate the relationship between Olympic (amateur) boxing and cerebrospinal fluid (CSF) brain injury biomarkers. Methods The study was designed as a prospective cohort study. Thirty Olympic boxers with a minimum of 45 bouts and 25 non-boxing matched controls were included in the study. CSF samples were collected by lumbar puncture 1–6 days after a bout and after a rest period for at least 14 days. The controls were tested once. Biomarkers for acute and chronic brain injury were analysed. Results NFL (mean ± SD, 532±553 vs 135±51 ng/L p = 0.001), GFAP (496±238 vs 247±147 ng/L p<0.001), T-tau (58±26 vs 49±21 ng/L p<0.025) and S-100B (0.76±0.29 vs 0.60±0.23 ng/L p = 0.03) concentrations were significantly increased after boxing compared to controls. NFL (402±434 ng/L p = 0.004) and GFAP (369±113 ng/L p = 0.001) concentrations remained elevated after the rest period. Conclusion Increased CSF levels of T-tau, NFL, GFAP, and S-100B in >80% of the boxers demonstrate that both the acute and the cumulative effect of head trauma in Olympic boxing may induce CSF biomarker changes that suggest minor central nervous injuries. The lack of normalization of NFL and GFAP after the rest period in a subgroup of boxers may indicate ongoing degeneration. The recurrent head trauma in boxing may be associated with increased risk of chronic traumatic brain injury.

APOE ε4 allele is associated with reduced cerebrospinal fluid levels of Aβ42

The ε4 allele of APOE is a risk factor for Alzheimer disease (AD). By analysis of a large cohort of AD patients (n = 563) and control subjects (n = 118), it is shown that the ε4 allele is strongly associated with reduced CSF levels of β-amyloid (1–42) (Aβ42) in both AD (p < 10−9) and control (p = 0.0012) populations. As no associations of APOE variants with other indexes of AD severity were observed, this effect may reflect a fundamental involvement of ApoE in Aβ metabolism.

Age and diagnostic performance of Alzheimer disease CSF biomarkers

Objectives: Core CSF changes in Alzheimer disease (AD) are decreased amyloid β1–42, increased total tau, and increased phospho-tau, probably indicating amyloid plaque accumulation, axonal degeneration, and tangle pathology, respectively. These biomarkers identify AD already at the predementia stage, but their diagnostic performance might be affected by age-dependent increase of AD-type brain pathology in cognitively unaffected elderly. Methods: We investigated effects of age on the diagnostic performance of CSF biomarkers in a uniquely large multicenter study population, including a cross-sectional cohort of 529 patients with AD dementia (median age 71, range 43–89 years) and 304 controls (67, 44–91 years), and a longitudinal cohort of 750 subjects without dementia with mild cognitive impairment (69, 43–89 years) followed for at least 2 years, or until dementia diagnosis. Results: The specificities for subjects without AD and the areas under the receiver operating characteristics curves decreased with age. However, the positive predictive value for a combination of biomarkers remained stable, while the negative predictive value decreased only slightly in old subjects, as an effect of the high AD prevalence in older ages. Conclusion: Although the diagnostic accuracies for AD decreased with age, the predictive values for a combination of biomarkers remained essentially stable. The findings highlight biomarker variability across ages, but support the use of CSF biomarkers for AD even in older populations.

Brain 5-HT1A, 5-HT1D, and 5-HT2 Receptors in suicide victims

We report on 5-HT1A, 5-HT1D, and 5-HT2 binding sites in 23 control subjects and 18 suicide victims subdivided according to the method of death and the previous existence of depressive symptoms. No difference in maximum binding (Bmax) or binding affinity (Kd) was found between the control and overall suicide groups for the binding sites studied. The drug overdose subgroup showed, however, a significant decrease in the 5-HT1A binding affinity, probably explained by the higher sensitivity of this binding site to the acute administration of tricyclic antidepressants. A significant decrease in 5-HT1D binding affinity was also found in the depressed suicides, together with a significant decrease in the number of 5-HT1D binding sites in the nondepressed suicides. Further studies should be carried out on the 5-HT1D binding site as it might represent a new tool in the understanding of the depressive illness.

Detection of Dementia in Primary Care: The Linköping Study

We examined to what extent dementia and cognitive impairment are detected in a primary health care centre. A systematic sample of patients aged 70 years and above, who attended a primary health care centre for a doctor’s consultation (n = 350) were examined with a neuropsychiatric examination and an interview with a close informant. Dementia was diagnosed according to DSM-III-R. Medical records from the health centre were examined for entries on cognitive decline or dementia, other diagnoses and prescribed drugs. The prevalence of dementia was 16.3% and a further 3.1% had questionable dementia. Cognitive disturbances or dementia were noted in case records in 15 out of 57 (26%) demented cases, and in 1 out of 11 (9%) questionable dementias. Compared to non-demented patients, the demented had more diagnoses and a higher number of prescribed drugs. Severity and duration of dementia were associated with an increased detection.

Dementia in primary care: why the low detection rate?

Objective - The aim of the present study was to find reasons for the low detection rate of dementia in primary care. Another aim was to investigate the attitudes and knowledge on dementia among Swedish general practitioners (GPs). Design - Two-hundred-and-twenty-eight postal questionnaires were distributed to GPs in the county of Östergötland. Setting - Primary care in Sweden. Main outcome measures - The opinions of GPs on dementia management in primary care. Results - The response rate was 67%. GPs showed a good knowledge of dementia diseases but underestimated the occurrence of dementia. They presented a positive attitude towards managing patients with dementia and considered that existing drug therapy justified an active search for patients with dementia in primary care, but they believed the efficacy of the drugs to be limited. Assessing the social environment of patients and organising social support were regarded as the most difficult tasks in the management of demented patients. Conclusion ? The study indicates that the main obstacles are a lack of resources and a sceptical attitude to the benefits of drug treatment. Co-operation between the community services, specialist clinics and the primary care team should be improved.OBJECTIVE The aim of the present study was to find reasons for the low detection rate of dementia in primary care. Another aim was to investigate the attitudes and knowledge on dementia among Swedish general practitioners (GPs). DESIGN Two-hundred-and-twenty-eight postal questionnaires were distributed to GPs in the county of Ostergötland. SETTING Primary care in Sweden. MAIN OUTCOME MEASURES The opinions of GPs on dementia management in primary care. RESULTS The response rate was 67%. GPs showed a good knowledge of dementia diseases but underestimated the occurrence of dementia. They presented a positive attitude towards managing patients with dementia and considered that existing drug therapy justified an active search for patients with dementia in primary care, but they believed the efficacy of the drugs to be limited. Assessing the social environment of patients and organising social support were regarded as the most difficult tasks in the management of demented patients. CONCLUSION The study indicates that the main obstacles are a lack of resources and a sceptical attitude to the benefits of drug treatment. Co-operation between the community services, specialist clinics and the primary care team should be improved.