The free plasma amyloid Aβ1-42/Aβ1-40 ratio predicts conversion to dementia for subjects with mild cognitive impairment with performance equivalent to that of the total plasma Aβ1-42/Aβ1-40 ratio. The BALTAZAR study

BACKGROUND AND PURPOSE

Blood-based biomarkers are a non-invasive solution to predict the risk of conversion of mild cognitive impairment (MCI) to dementia. The utility of free plasma amyloid peptides (not bound to plasma proteins and/or cells) as an early indicator of conversion to dementia is still debated, as the results of studies have been contradictory. In this context, we investigated whether plasma levels of the free amyloid peptides Aβ1-42 and Aβ1-40 and the free plasma Aβ1-42/Aβ1-40 ratio are associated with the conversion of MCI to dementia, in particular AD, over three years of follow-up in a subgroup of the BALTAZAR cohort. We also compared their predictive value to that of total plasma Aβ1-42 and Aβ1-40 levels and the total plasma Aβ1-42/Aβ1-40 ratio.

METHODS

The plasma Aβ1-42 and Aβ1-40 peptide assay was performed using the INNO-BIA kit (Fujirebio Europe). Free amyloid levels (defined by the amyloid fraction directly accessible to antibodies of the assay) were obtained with the undiluted plasma, whereas total amyloid levels were obtained after the dilution of plasma (1/3) with a denaturing buffer. Free and total Aβ1-42 and Aβ1-40 levels were measured at inclusion for a subgroup of participants (N = 106) with mild cognitive impairment (MCI) from the BALTAZAR study (a large-scale longitudinal multicenter cohort with a three-year follow-up). Associations between conversion and the free/total plasma Aβ1-42 and Aβ1-40 levels and Aβ1-42/Aβ1-40 ratio were analyzed using logistic and Cox Proportional Hazards models. Demographic, clinical, cognitive (MMSE, ADL and IADL), APOE, and MRI characteristics (relative hippocampal volume) were compared using non-parametric (Mann-Whitney) or parametric (Student) tests for quantitative variables and Chi-square or Fisher exact tests for qualitative variables.

RESULTS

The risk of conversion to dementia was lower for patients in the highest quartile of free plasma Aβ1-42/Aβ1-40 (≥ 25.8%) than those in the three lower quartiles: hazard ratio = 0.36 (95% confidence interval [0.15-0.87]), after adjustment for age, sex, education, and APOE ε4 (p-value = 0.022). This was comparable to the risk of conversion in the highest quartile of total plasma Aβ1-42/Aβ1-40: hazard ratio = 0.37 (95% confidence interval [0.16-0.89], p-value = 0.027). However, while patients in the highest quartile of total plasma Aβ1-42/Aβ1-40 showed higher MMSE scores and a higher hippocampal volume than patients in the three lowest quartiles of total plasma Aβ1-42/Aβ1-40, as well as normal CSF biomarker levels, the patients in the highest quartile of free plasma Aβ1-42/Aβ1-40 did not show any significant differences in MMSE scores, hippocampal volume, or CSF biomarker levels relative to the three lowest quartiles of free plasma Aβ1-42/Aβ1-40.

CONCLUSION

The free plasma Aβ1-42/Aβ1-40 ratio is associated with a risk of conversion from MCI to dementia within three years, with performance comparable to that of the total plasma Aβ1-42/Aβ1-40 ratio. Threshold levels of the free and total plasma Aβ1-42/Aβ1-40 ratio could be determined, with a 60% lower risk of conversion for patients above the threshold than those below.

Orthostatic hypotension and orthostatic hypertension are both associated with lower cognitive function: The S.AGES cohort

BACKGROUND

Blood pressure (BP) postural changes, both orthostatic hypotension (OHYPO) and orthostatic hypertension (OHYPER) are common in older adults. Few studies have investigated their association with cognition, particularly for OHYPER, an emerging cardiovascular risk factor. We aimed to assess the association between OHYPO, OHYPER and cognition in non-institutionalized older subjects.

METHODS

The S.AGES (Sujets ÂGES, Aged Subjects) cohort followed every 6 months for 3 years non-institutionalized subjects aged ≥65 years without dementia at inclusion, in France. OHYPO and OHYPER were respectively defined as a fall or an increase of ≥20 mmHg in systolic BP and/or ≥10 mmHg in diastolic BP after standing from a sitting position. Cognition was assessed using the Mini-Mental State Examination (MMSE). Linear mixed models were used for the analyses.

RESULTS

Among the 3170 subjects included (mean age 78 years, 56% women), 209 (6.5%) had OHYPO and 226 (7.1%) had OHYPER at baseline. After adjustment for demographics, cardiovascular risk factors and disease, seated SBP/DBP and BP lowering treatment, mean MMSE was 0.52 point lower in participants with OHYPER compared to those with normal BP postural changes (β adjusted [95% CI] = -0.52 [-0.96; -0.09], p = 0.02) and 0.50 point lower in participants with OHYPO compared to those with normal BP postural changes (β adjusted [95% CI] = -0.50 [-0.95; -0.06], p = 0.03). Sensitivity analyses showed a dose-response relationship between OHYPO and cognition.

CONCLUSION

Although the absolute differences in MMSE were small, both OHYPO and OHYPER were associated with lower cognition. Orthostatic BP measurements could help identify patients with risk of cognitive impairment. Further studies are needed to assess whether controlling orthostatic BP could be a promising interventional target in preserving cognition among older adults.

Therapeutic management in ambulatory elderly patients with atrial fibrillation: the S.AGES cohort

Few epidemiologic studies have specifically focused on very old community dwelling population with atrial fibrillation (AF). The objectives of the AF-S.AGES cohort were to describe real-life therapeutic management of non-institutionalized elderly patients with AF according to age groups, i.e., 65-79 and ≥ 80 and to determine the main factors associated with anticoagulant treatment in both groups.

METHODS

Observational study (N=1072) aged ≥ 65 years old, recruited by general practitioners. Characteristics of the sample were first evaluated in the overall sample and according to age (< 80 or ≥ 80 years) and to use of anticoagulant treatment at inclusion. Logistic models were used to analyze the determinants of anticoagulant prescription among age groups.

RESULTS

Mean age was 78.0 (SD=6.5) years and 42% were ≥ 80 years. Nineteen percent had paroxysmal AF, 15% persistent, 56% permanent and 10% unknown type, 77% were treated with vitamin K antagonists (VKA), 17% with antiplatelet therapy with no differences between age groups. Rate-control drugs were more frequently used than rhythm-control drugs (55% vs. 37%, p < 0.001). VKA use was associated with permanent AF, younger age and cancer in patients ≥ 80 years old and with permanent AF and preserved functional autonomy in patients < 80 years old. Hemorrhagic scores were independently associated with non-use of VKA whereas thromboembolic scores were not associated with VKA use.

CONCLUSIONS

In this elderly AF outpatient population, use of anticoagulant therapy was higher even after 80 years than in previous studies suggesting that recent international guidelines are better implemented in the elderly population.

Capacity to consent to biomedical research's evaluation among older cognitively impaired patients. A study to validate the University of California Brief Assessment of Capacity to Consent questionnaire in French among older cognitively impaired patients

CONTEXT

Some studies have highlighted the difficulty for physicians to evaluate patient's ability to consent to bio-medical research in the elderly population. The University of California Brief Assessment of Capacity to Consent (UBACC) is a rapid questionnaire to assess the ability to consent, previously validated among schizophrenic patients.

OBJECTIVE

To evaluate the accuracy of the UBACC scale, French version, to determine the capacity to consent to biomedical studies of older people with normal cognition, mild cognitive impairment (MCI) or Alzheimer Disease (AD).

DESIGN

A prospective validation study between September 2008 to November 2011.

SETTING

A Memory clinic.

PATIENTS

We included 61 subjects in a memory clinic who had already consented to participate to a biomedical research and had signed a consent form. Those subjects, who had memory impairment, had a comprehensive neuro-psychological (including Mini Mental State Examination (MMSE)/30), clinical, biological assessment and brain imagery during day-care hospital. They were classified as MCI or AD patients. Control group included patients' caregivers without memory complaints and a normal comprehensive neuro-psychological assessment.

INTERVENTION AND MEASUREMENTS

The consent form was once again explained to the subjects by a physician who subjectively evaluated if subjects had understood the study. Then, the 10 questions of the French version of the UBACC scale (max score 20) were asked to the participants. This scale evaluates the understanding of the study's aim, risks and benefits. A comparison was made between subjective assessment and the UBACC score.

RESULTS

The physician considered that 18/61 patients (2 MCI and 16 AD) had not understood. These ones had a lower UBACC score (Score/20 (SD) [range]: 7.56 (3.03) [0-12] versus 17.72 (2.68) [13-28], p<0.001), a lower MMSE (Score/ 30 (SD): 21.1 (5.9) versus 27.3 (2.9); p<0.001) and were older (age (years old) 80.8 versus 76.6. p<0.0001) compared to those who had understood. Moreover, all the patients who had not understood had an UBACC score ≤ 12. The administration time was accurate in this population (<10 minutes).

CONCLUSION

The UBACC scale, in its French version, was accurate to assess capacity to consent in an older, cognitively impaired population.

Factors predicting improvement in motor disability in writer's cramp treated with botulinum toxin

OBJECTIVE

To identify factors predicting improvement in motor disability in writer's cramp treated with botulinum toxin (BTX).

METHODS

47 patients with writer's cramp were treated with BTX and were evaluated by the same neurologists at initial referral, after each BTX injection, and when the effect of BTX was maximal at the time of the study. Patients and examiners simultaneously and independently rated the efficacy of BTX injections. Self assessment was a global clinical impression of the impact of treatment on writing quality, writing speed, writing errors, and legibility of handwriting; for objective assessment, the examiners used the Burke-Fahn-Marsden (BFM) scale.

RESULTS

On the BFM scale, there was a significant improvement (p<0.0001) in both severity and disability scores. Patients with a pronation/flexion pattern of dystonia showed the best and the most sustained improvement. Primary writing tremor was little improved. There was a correlation between the self assessment score and the Burke-Fahn-Marsden score. Benefit was maintained over time

CONCLUSIONS

These results have implications for the identification of patients most likely to benefit from BTX injections.

Association of polymorphisms in the Tau and Saitohin genes with Parkinson's disease

BACKGROUND

The Saitohin gene has recently been identified in intron 9 of the Tau gene. Because an association between Parkinson's disease and Tau has been described, Saitohin represents a candidate gene for Parkinson's disease.

OBJECTIVE

To test these two genes for their association with Parkinson's disease in a large community based case-control study.

RESULTS

Cases (n = 208) were more often homozygotes for the Tau H1 haplotype than controls (n = 483; odds ratio (OR) = 1.71 (95% confidence interval, 1.20 to 2.43); p = 0.003), and the saitohin Q allele was in complete linkage disequilibrium with the H1 haplotype. This association was stronger among cases with Parkinson's disease onset below 65 years (< or =65 years: OR = 2.52 (1.49 to 4.25); p<0.001) than among those with older onset (>65 years: OR = 1.20 (0.73 to 1.98); p<0.47).

CONCLUSIONS

The data suggest that there is a functional polymorphism at this locus involved in Parkinson's disease.

[Movement disorders and botulinum toxin in neurology]

Botulinum toxin has been a useful treatment in many movement disorders and more recently in other non-neurological motor dysfunctions for more than 15 years. Here, we review the various indications in neurology, mainly in the field of movement disorders. From 1973 to 2002, we searched the Medline database on this topic. We selected the most useful and relevant papers, with a special interest in dystonia. We summarized the results in the main indications (spasmodic torticollis, bleparospasm, hemifacial spasm) and in other manifestations such as writer's cramp, oromandibular dystonia, tremor, tics and myoclonus. We discuss the data of literature and compare them with the experience of the French movement disorders groups.