Alzheimer Disease: Dichgans M

Hachinski V, Iadecola C, Petersen RC, Breteler MM, Nyenhuis DL, Black SE, Powers WJ, DeCarli C, Merino JG, Kalaria RN, Vinters HV, Holtzman DM, Rosenberg GA, Wallin A, Dichgans M, Marler JR, Leblanc GG. · London Health Sciences Centre, University Campus, London, Ontario, Canada. · Stroke. · Pubmed #16917086 links to  free full text

Abstract: BACKGROUND AND PURPOSE: One in 3 individuals will experience a stroke, dementia or both. Moreover, twice as many individuals will have cognitive impairment short of dementia as either stroke or dementia. The commonly used stroke scales do not measure cognition, while dementia criteria focus on the late stages of cognitive impairment, and are heavily biased toward the diagnosis of Alzheimer disease. No commonly agreed standards exist for identifying and describing individuals with cognitive impairment, particularly in the early stages, and especially with cognitive impairment related to vascular factors, or vascular cognitive impairment. METHODS: The National Institute for Neurological Disorders and Stroke (NINDS) and the Canadian Stroke Network (CSN) convened researchers in clinical diagnosis, epidemiology, neuropsychology, brain imaging, neuropathology, experimental models, biomarkers, genetics, and clinical trials to recommend minimum, common, clinical and research standards for the description and study of vascular cognitive impairment. RESULTS: The results of these discussions are reported herein. CONCLUSIONS: The development of common standards represents a first step in a process of use, validation and refinement. Using the same standards will help identify individuals in the early stages of cognitive impairment, will make studies comparable, and by integrating knowledge, will accelerate the pace of progress.

Kölsch H, Jessen F, Wiltfang J, Lewczuk P, Dichgans M, Kornhuber J, Frölich L, Heuser I, Peters O, Schulz JB, Schwab SG, Maier W. · Department of Psychiatry, University of Bonn, Bonn, Germany. · Neurosci Lett. · Pubmed #18541377 No free full text.

Abstract: SORL1 gene variants were described as risk factors of Alzheimer's disease (AD). We investigated the association of four SORL1 variants with CSF levels of Abeta42 and Abeta40 in 153 AD patients recruited from a multicenter study of the German Competence Net Dementias. Only one SORL1 SNP was associated with altered Abeta42 levels in the single marker analysis (SNP21: p=0.011), the other SNPs did not show an association with Abeta42 or Abeta40 CSF levels. Haplotype analysis identified a three marker SORL1 haplotype consisting of SNP19 T-allele, SNP21 G-allele and SNP23 A-allele (T/G/A) which was associated with reduced Abeta42 CSF levels in AD patients (p=0.003). Abeta40 levels were also lower in carriers of this haplotype; however, this did not reach statistical significance (p=0.15). We found a SORL1 haplotype which was associated with CSF levels of amyloid-beta cleavage products, measured as altered levels of Abeta42. Thus our data suggest that SORL1 gene variants might influence AD pathology.

Peters N, Holtmannspötter M, Opherk C, Gschwendtner A, Herzog J, Sämann P, Dichgans M. · Department of Neurology, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany. · Neurology. · Pubmed #16717211 No free full text.

Abstract: BACKGROUND: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited small vessel disease causing stroke and subcortical vascular dementia. Recent studies in sporadic subcortical ischemic vascular disease have drawn attention to brain atrophy as a clinically important marker of disease progression. However, little is known about the role of brain atrophy and its clinical correlates in CADASIL. METHOD: The authors determined the normalized brain volume (NBV) and percent brain volume change (PBVC) over 2 years in 76 CADASIL subjects (45.1 +/- 9.7 years) using the SIENA (structural image evaluation using normalization of atrophy) software and its adaptation for cross-sectional measurements (SIENAX). Baseline assessments included systolic blood pressure (SBP), homocysteine levels, BMI, and APOE genotyping. T2-lesion volumes and clinical scales were assessed at both time points. RESULTS: The NBV significantly correlated with all clinical scores (Rankin, NIH Stroke Scale, Barthel, structured interview for the diagnosis of Alzheimer dementia and multi-infarct dementia, Mattis dementia rating scale) at both time points independently of age and sex. PBVC correlated with changes of all clinical scores (all p < 0.01) except for the Mattis dementia rating scale (p = 0.10). In a linear regression model, age (p < 0.001), male sex (p < 0.01), and SBP (p = 0.07) were the main risk factors for a lower NBV at baseline. Age (p < 0.001) and SBP (p = 0.01) were risk factors for brain volume loss during follow-up. Sample size estimates showed that the number of individuals needed to demonstrate a treatment effect in a trial can be reduced when PBVC is used as an endpoint. CONCLUSIONS: This study identifies brain atrophy as an important aspect of the disease process in CADASIL and establishes significant correlations with multiple clinical aspects including cognition. Age and systolic blood pressure are risk factors for brain volume loss during follow-up. Percent brain volume change seems promising as an adjunct outcome measure in future interventional trials.

Holtmannspötter M, Peters N, Opherk C, Martin D, Herzog J, Brückmann H, Sämann P, Gschwendtner A, Dichgans M. · Abteilung für Neuroradiologie, Klinikum Grosshadern, Ludwig-Maximilians-Universität, Munich, Germany. · Stroke. · Pubmed #16269644 links to  free full text

Abstract: BACKGROUND AND PURPOSE: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a cerebral small vessel disease caused by mutations in the NOTCH3 gene. MRI is sensitive in detecting preclinical involvement and changes over time. However, little is known about correlations between MRI metrics and clinical measures on a longitudinal scale. In this study, we assessed the role of quantitative MRI (T2-lesion volume and diffusion tensor imaging [DTI]-derived metrics) in monitoring and predicting disease progression. METHODS: Sixty-two CADASIL subjects were followed prospectively over a period of 26.3+/-1.2 months. Dual-echo scans, DTI scans, and clinical scales were obtained at baseline and at follow-up. T2-lesion volumes were determined quantitatively, and histograms of mean diffusivity (MD) were produced. RESULTS: At follow-up, T2-lesion volumes and MD histogram metrics had changed significantly (all P<0.01). Lesion volumes and average MD correlated with clinical scores at baseline. Changes of average MD correlated with changes of the Rankin score, the National Institutes of Health Stroke Scale score, and the structured interview for the diagnosis of Alzheimer dementia and multiinfarct dementia score (all P<0.01). On multivariate analysis, average MD and systolic blood pressure at baseline were predictors of changes of average MD during follow-up. Moreover, average MD was the main predictor of clinical progression. Sample size estimates showed that the number of individuals required to detect a treatment effect in an interventional trial may be reduced when using MD histograms as an end point. CONCLUSIONS: This study establishes correlations between changes of DTI histogram metrics and clinical measures over time. DTI histograms may be used as an adjunct outcome measure in future therapeutic trials. Moreover, DTI histogram metrics predict disease progression in CADASIL.

Dichgans M. · Neurologische Klinik, Klinikum Grosshadern, Munich, Germany. · Int Psychogeriatr. · Pubmed #16191212 No free full text.

Abstract: Monogenic disorders account for only a minority of strokes. Yet, they have been particularly helpful in exploring basic disease mechanisms. This article summarizes some recent data on monogenic stroke while focusing on two conditions: CADASIL, as a genetic variant of ischemic small vessel disease, and familial forms of cerebral amyloid angiopathy, which share many properties with sporadic disease.

Peters N, Herzog J, Opherk C, Dichgans M. · Department of Neurology, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany. · Stroke. · Pubmed #15155961 links to  free full text

Abstract: BACKGROUND AND PURPOSE: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited small vessel disease causing stroke and dementia. The aim of this study was to explore the patterns of clinical progression in CADASIL, to check for prognostic variables, and to provide sample size estimates for future therapeutic trials. METHODS: Eighty CADASIL subjects (aged 45.7+/-9.9 years [mean+SD]) were followed prospectively during a mean period of 26.3+/-1.1 months. Standardized scales on disability (Rankin), activities of daily living (Barthel index), neurological outcome (National Institutes of Health Stroke Scale [NIHSS]), and cognition (structural interview for diagnosis of Alzheimer dementia and multi-infarct dementia [SIDAM] and Mattis dementia rating scale [MDRS]) were assessed at baseline and at follow-up. RESULTS: All but 1 individual completed the protocol. At follow-up, the cohort had deteriorated with respect to all clinical scales: Rankin scores (0.3+/-0.7 [mean change+/-SD]; P=0.001), Barthel index (-5.4+/-15.9; P<0.001), NIHSS scores (1.0+/-2.6; P=0.001), SIDAM scores (-2.1+/-6.4; P=0.004), and MDRS scores (-4.3+18.5; P=0.09). The spectrum ranged from marked worsening to some degree of improvement. Seventeen patients experienced a new stroke. Overall, there were 18 strokes within 173 person-years, giving an average incidence rate of stroke of 10.4 per 100 person-years (95% CI, 5.6 to 15.2). Age at baseline was found to be a predictor of clinical progression. Sample size estimates show that the number of individuals needed to include in an interventional trial (assumed duration 2 years, assumed treatment effect 40%) is 602 when using stroke occurrence as an outcome measure. CONCLUSIONS: The clinical course of CADASIL includes periods of acute worsening, chronic progression, stabilization, and improvement. Sample size calculations emphasize the need for surrogate markers of disease progression for future interventional trials.