Alina Solomon

Alzheimer's disease: clinical trials and drug development

Alzheimers disease is the most common cause of dementia in elderly people. Research into Alzheimers disease therapy has been at least partly successful in terms of developing symptomatic treatments, but has also had several failures in terms of developing disease-modifying therapies. These successes and failures have led to debate about the potential deficiencies in our understanding of the pathogenesis of Alzheimers disease and potential pitfalls in diagnosis, choice of therapeutic targets, development of drug candidates, and design of clinical trials. Many clinical and experimental studies are ongoing, but we need to acknowledge that a single cure for Alzheimers disease is unlikely to be found and that the approach to drug development for this disorder needs to be reconsidered. Preclinical research is constantly providing us with new information on pieces of the complex Alzheimers disease puzzle, and an analysis of this information might reveal patterns of pharmacological interactions instead of single potential drug targets. Several promising randomised controlled trials are ongoing, and the increased collaboration between pharmaceutical companies, basic researchers, and clinical researchers has the potential to bring us closer to developing an optimum pharmaceutical approach for the treatment of Alzheimers disease.

A 2 year multidomain intervention of diet, exercise, cognitive training, and vascular risk monitoring versus control to prevent cognitive decline in at-risk elderly people (FINGER): a randomised controlled trial

BACKGROUND Modifiable vascular and lifestyle-related risk factors have been associated with dementia risk in observational studies. In the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER), a proof-of-concept randomised controlled trial, we aimed to assess a multidomain approach to prevent cognitive decline in at-risk elderly people from the general population. METHODS In a double-blind randomised controlled trial we enrolled individuals aged 60-77 years recruited from previous national surveys. Inclusion criteria were CAIDE (Cardiovascular Risk Factors, Aging and Dementia) Dementia Risk Score of at least 6 points and cognition at mean level or slightly lower than expected for age. We randomly assigned participants in a 1:1 ratio to a 2 year multidomain intervention (diet, exercise, cognitive training, vascular risk monitoring), or a control group (general health advice). Computer-generated allocation was done in blocks of four (two individuals randomly allocated to each group) at each site. Group allocation was not actively disclosed to participants and outcome assessors were masked to group allocation. The primary outcome was change in cognition as measured through comprehensive neuropsychological test battery (NTB) Z score. Analysis was by modified intention to treat (all participants with at least one post-baseline observation). This trial is registered at ClinicalTrials.gov, number NCT01041989. FINDINGS Between Sept 7, 2009, and Nov 24, 2011, we screened 2654 individuals and randomly assigned 1260 to the intervention group (n=631) or control group (n=629). 591 (94%) participants in the intervention group and 599 (95%) in the control group had at least one post-baseline assessment and were included in the modified intention-to-treat analysis. Estimated mean change in NTB total Z score at 2 years was 0·20 (SE 0·02, SD 0·51) in the intervention group and 0·16 (0·01, 0·51) in the control group. Between-group difference in the change of NTB total score per year was 0·022 (95% CI 0·002-0·042, p=0·030). 153 (12%) individuals dropped out overall. Adverse events occurred in 46 (7%) participants in the intervention group compared with six (1%) participants in the control group; the most common adverse event was musculoskeletal pain (32 [5%] individuals for intervention vs no individuals for control). INTERPRETATION Findings from this large, long-term, randomised controlled trial suggest that a multidomain intervention could improve or maintain cognitive functioning in at-risk elderly people from the general population. FUNDING Academy of Finland, La Carita Foundation, Alzheimer Association, Alzheimers Research and Prevention Foundation, Juho Vainio Foundation, Novo Nordisk Foundation, Finnish Social Insurance Institution, Ministry of Education and Culture, Salama bint Hamdan Al Nahyan Foundation, Axa Research Fund, EVO funding for University Hospitals of Kuopio, Oulu, and Turku and for Seinäjoki Central Hospital and Oulu City Hospital, Swedish Research Council, Swedish Research Council for Health, Working Life and Welfare, and af Jochnick Foundation.

The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER): Study design and progress

Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) is a multi‐center, randomized, controlled trial ongoing in Finland.

Cholesterol as a risk factor for Alzheimer's disease – epidemiological evidence

Although dementia is usually a late‐life syndrome, it is now well known that pathological changes begin quite early in adulthood, outside the classical age borders of geriatric specialties. In order to design effective preventive strategies, adequate information can only be gathered by taking a life‐long view of Alzheimers disease (AD). Dementia risk is the result of exposure to both harmful and protective factors along the life course, and these factors, as well as their impact on the individuals health status, change over time. This review aims at presenting current epidemiological data on serum cholesterol levels and dietary fat intake as risk factors for dementia/AD, and at discussing the reasons and significance of contradictions between various studies. Reducing dementia risk may be possible by influencing the serum lipid profile. A more detailed characterization of the mechanisms behind the association of cholesterol (in both serum and brain) with dementia/AD, mechanisms about which little is currently known, would allow a better translation of research findings into clinical practice.

Dementia prevention: current epidemiological evidence and future perspective.

Dementia, a major cause of disability and institutionalization in older people, poses a serious threat to public health and to the social and economic development of modern society. Alzheimers disease (AD) and cerebrovascular diseases are the main causes of dementia; most dementia cases are attributable to both vascular and neurodegenerative brain damage. No curative treatment is available, but epidemiological research provides a substantial amount of evidence of modifiable risk and protective factors that can be addressed to prevent or delay onset of AD and dementia. Risk of late-life dementia is determined by exposures to multiple factors experienced over the life course, and the effect of specific risk/protective factors depends largely on age. Moreover, cumulative and combined exposure to different risk/protective factors can modify their effect on dementia/AD risk. Multidisciplinary research involving epidemiology, neuropathology, and neuroimaging has provided sufficient evidence that vascular risk factors significantly contribute to the expression and progression of cognitive decline (including dementia) but that active engagement in social, physical, and mentally stimulating activities may delay the onset of dementia. However, these findings need to be confirmed by randomized controlled trials (RCTs). A promising strategy for preventing dementia is to implement intervention programs that take into account both the life-course model and the multifactorial nature of this syndrome. In Europe, there are three ongoing multidomain interventional RCTs that focus on the optimal management of vascular risk factors and vascular diseases. The RCTs include medical and lifestyle interventions and promote social, mental, and physical activities aimed at increasing the cognitive reserve. These studies will provide new insights into prevention of cognitive impairment and dementia. Such knowledge can help researchers plan larger, international prevention trials that could provide robust evidence on dementia/AD prevention. Taking a step in this direction, researchers involved in these European RCTs recently started the European Dementia Prevention Initiative, an international collaboration aiming to improve strategies for preventing dementia.

Serum total cholesterol, statins and cognition in non-demented elderly

BACKGROUND The association between serum total cholesterol (TC), lipid-lowering drugs and cognition in the elderly is currently controversial. OBJECTIVE To investigate the relationship between TC, lipid-lowering drugs and cognitive functions in non-demented elderly. DESIGN AND SETTING Participants of the Cardiovascular risk factors, aging and dementia (CAIDE) study were derived from random, population-based samples previously studied in 1972, 1977, 1982 or 1987. Analyses are based on 1382 non-demented participants re-examined in 1998 after an average follow-up of 21 years. RESULTS High midlife TC was associated with poorer late-life episodic memory and category fluency. TC decreased in most individuals over time. A more pronounced decrease was related to poorer late-life episodic memory and psychomotor speed, but not if subjects used statins. CONCLUSIONS The TC-cognition relationship seems bidirectional. High midlife TC is associated with poorer late-life cognition, but decreasing TC after midlife may reflect poorer cognitive status. Statins may be beneficial for cognition in non-demented elderly.

Midlife Vascular Risk Factors and Alzheimer's Disease: Evidence from Epidemiological Studies

The shared risk factor profile between cardiovascular diseases and Alzheimers disease (AD), observations on vascular pathology in AD, and altered cerebral blood flow in AD brains have led to the suggestion that AD might be a vascular disorder with neurodegenerative consequences. Targeting vascular and metabolic risk factors could be an effective way to prevent AD. Higher body mass index, elevated blood pressure, serum cholesterol concentrations, and impaired glucose regulation have been associated with increased risk of AD. Interestingly, the associations between these factors measured at mid-life are stronger, or even opposite, than with the risk factors measured at late-life. This may reflect true differences in the association (i.e., mid-life risk factors being a better measure of vascular load during adulthood), reverse causality, or bias. The vascular risk factors can directly increase the susceptibility to AD, or the effect can be mediated via cardio- and cerebrovascular diseases.

Associations between serum homocysteine, holotranscobalamin, folate and cognition in the elderly: a longitudinal study

Abstract.  Hooshmand B, Solomon A, Kåreholt I, Rusanen M, Hänninen T, Leiviskä J, Winblad B, Laatikainen T, Soininen H & Kivipelto M (Aging Research Center, Karolinska Institutet, Stockholm, Sweden; KI Alzheimer’s Disease Research Center (KI‐ADRC), Karolinska Institutet, Stockholm, Sweden; National Institute for Health and Welfare (THL), Helsinki, Finland; University of Eastern Finland, Institute of Clinical Medicine, and University Hospital, Kuopio, Finland). Associations between serum homocysteine, holotranscobalamin, folate and cognition in the elderly: a longitudinal study. J Intern Med 2012; 271: 204–212.

Plasma homocysteine, Alzheimer and cerebrovascular pathology: a population-based autopsy study.

Elevated plasma total homocysteine is associated with increased risk of dementia/Alzheimers disease, but underlying pathophysiological mechanisms are not fully understood. This study investigated possible links between baseline homocysteine, and post-mortem neuropathological and magnetic resonance imaging findings up to 10 years later in the Vantaa 85+ population including people aged ≥85 years. Two hundred and sixty-five individuals had homocysteine and autopsy data, of which 103 had post-mortem brain magnetic resonance imaging scans. Methenamine silver staining was used for amyloid-β and modified Bielschowsky method for neurofibrillary tangles and neuritic plaques. Macroscopic infarcts were identified from cerebral hemispheres, brainstem and cerebellum slices. Standardized methods were used to determine microscopic infarcts, cerebral amyoloid angiopathy, and α-synuclein pathology. Magnetic resonance imaging was used for visual ratings of the degree of medial temporal lobe atrophy, and periventricular and deep white matter hyperintensities. Elevated baseline homocysteine was associated with increased neurofibrillary tangles count at the time of death: for the highest homocysteine quartile, odds ratio (95% confidence interval) was 2.60 (1.28-5.28). The association was observed particularly in people with dementia, in the presence of cerebral infarcts, and with longer time between the baseline homocysteine assessment and death. Also, elevated homocysteine tended to relate to amyloid-β accumulation, but this was seen only with longer baseline-death interval: odds ratio (95% confidence interval) was 2.52 (0.88-7.19) for the highest homocysteine quartile. On post-mortem magnetic resonance imaging, for the highest homocysteine quartile odds ratio (95% confidence interval) was 3.78 (1.12-12.79) for more severe medial temporal atrophy and 4.69 (1.14-19.33) for more severe periventricular white matter hyperintensities. All associations were independent of several potential confounders, including common vascular risk factors. No relationships between homocysteine and cerebral macro- or microinfarcts, cerebral amyoloid angiopathy or α-synuclein pathology were detected. These results suggest that elevated homocysteine in adults aged ≥85 years may contribute to increased Alzheimer-type pathology, particularly neurofibrillary tangles burden. This effect seems to be more pronounced in the presence of cerebrovascular pathology. Randomized controlled trials are needed to determine the impact of homocysteine-lowering treatments on dementia-related pathology.

Plasma levels of 24S-hydroxycholesterol reflect brain volumes in patients without objective cognitive impairment but not in those with Alzheimer's disease.

OBJECTIVES Cholesterol has been linked to Alzheimers disease (AD) and plasma 24S-hydroxycholesterol (24OHC) has been suggested as a surrogate marker for brain cholesterol metabolism. This study investigates the relation of 24OHC as well as markers of extracerebral cholesterol homeostasis (lanosterol, lathosterol, cholesterol, LDL-C, HDL-C and 27-hydroxycholesterol) with brain volumes in memory clinic patients. METHODS 96 patients (33 with subjective cognitive impairment--SCI; 36 with mild cognitive impairment--MCI; 27 with AD) referred to the Memory Clinic at Karolinska University Hospital, Sweden. Plasma assessments were done by isotope dilution-mass spectrometry. MRI measurements were done using custom-made software BMAP (imaging laboratory, Karolinska Institutet), running on HERMES platform. RESULTS Ratios of 24-hydroxycholesterol, 27-hydroxycholesterol, lanosterol and lathosterol to cholesterol (R_24OHC, R_27OHC, R_lanosterol and R_lathosterol) were significantly lower in patients with AD. In the whole population, after controlling for age, sex, APOE genotype and statins, R_24OHC was positively related to gray matter (GM) fraction. However, when groups were considered separately, the relation to GM volume, GM and parenchymal fractions was significant in the SCI group only (p<0.05). There was a significant positive association between cholesterol and white matter (WM) volume, WM and parenchymal fractions in patients with AD. CONCLUSIONS Plasma R_24OHC was lower in patients with AD, but R_24OHC was significantly related to brain volumes in the control group only. One reason may be the previously demonstrated abnormal expression of cholesterol 24S-hydroxylase in astrocytes in AD, which may limit the usefulness of this plasma marker in this specific disease. The findings on cholesterol agree with previous reports of decreasing plasma cholesterol levels in AD patients, suggesting a CNS-mediated effect on extracerebral cholesterol homeostasis.