Investigating virtual reality navigation in amnestic mild cognitive impairment using fMRI.

Spatial navigation requires a well-established network of brain regions, including the hippocampus, caudate nucleus, and retrosplenial cortex. Amnestic Mild Cognitive Impairment (aMCI) is a condition with predominantly memory impairment, conferring a high predictive risk factor for dementia. aMCI is associated with hippocampal atrophy and subtle deficits in spatial navigation. We present the first use of a functional Magnetic Resonance Imaging (fMRI) navigation task in aMCI, using a virtual reality analog of the Radial Arm Maze. Compared with controls, aMCI patients showed reduced activity in the hippocampus bilaterally, retrosplenial cortex, and left dorsolateral prefrontal cortex. Reduced activation in key areas for successful navigation, as well as additional regions, was found alongside relatively normal task performance. Results also revealed increased activity in the right dorsolateral prefrontal cortex in aMCI patients, which may reflect compensation for reduced activations elsewhere. These data support suggestions that fMRI spatial navigation tasks may be useful for staging of progression in MCI.

Alterations in working memory networks in amnestic mild cognitive impairment.

Patients with amnestic mild cognitive impairment (aMCI) show preserved or mildly impaired working memory, despite their deficits in episodic memory. We aimed to identify performance and/or neural differences between aMCI patients and matched controls on a standard working memory fMRI task. Neuropsychological assessment demonstrated aMCI impairments in verbal and visual episodic long-term memory, with intact IQ and executive function. Participants completed a standard three-level N-back task where patients were unimpaired. Functional activations in the control group were found in expected areas, including the inferior parietal lobule and dorsolateral prefrontal cortex. Group differences were found in the insula and lingual gyrus and, in a region of interest analysis, in the hippocampus. In all cases, these were caused by an absence of task-related deactivations in the aMCI group. The results are consistent with reports of failure in task-related deacivations in aMCI and could be early indications of pathology.

Age-related neural activity during allocentric spatial memory.

Age-related decline in allocentric (viewer-independent) spatial memory is seen across species. We employed a virtual reality analogue of the Morris Water Maze to study the effect of healthy ageing on neural activity during allocentric spatial memory using functional magnetic resonance imaging. Voxel-based morphometry was used to ascertain hippocampal volumetric integrity. A widespread neural network comprising frontal, parietal, occipital, thalamic, and cerebellar regions was activated in young and older adults, but only young adults significantly activated bilateral hippocampus and left parahippocampus, as well as right frontal pole and dorso-lateral prefrontal cortex (DLPFC) during encoding and right DLPC during retrieval. Hippocampal grey matter volume was unchanged in older adults; however, prefrontal and parahippocampal functional attenuation was accompanied by volumetric reduction. We conclude that the decline in allocentric spatial memory with age is associated with attenuated hippocampal function, as well as compromised function and structure of prefrontal and parahippocampal regions.

Nutritional supplementation in community-dwelling elderly people.

There is a large evidence base for nutritional intervention in acutely ill and post-operative hospitalised patients, but the evidence base for nursing home (NH) residents is small. The prevalence of poor nutrition in NHs is high and baseline nutrition appears to be an important determinant of response to nutritional intervention. Residents with mininutritional assessment (MNA) scores above 23.5 tend to show less response than those with lower scores. This relates in part to failure to increase intake in the better nourished as well as to actual response to increased intake. At the low end of the MNA spectrum, the increasing prevalence of multiple pathologies tends to result in a reduced response, but randomised controlled studies in this group is probably not ethical. Most studies have tended to investigate the intermediate group with MNA scores of 17-23.5 or equivalent using other scales. Interventions have usually resulted in increased intake of calories and micronutrients. Other end points have variously shown responses including weight, immunological measures, infection rates, decubitus ulcers, falls and fracture rates. Many studies have been too small to demonstrate benefit and some are likely to have suffered from type l errors - showing benefit by chance. Poorly quantifiable variables likely to be of importance include the local environment and catering as well as pathophysiological variability.

Selective AT1 receptor antagonism enhances sympathetically mediated vasoconstriction in man.

The vasoconstrictive action of angiotensin II (AII) is partly, sympathetically mediated and angiotensin-converting enzyme (ACE) inhibitors appear to exert a sympatholytic effect. We examine the effect of an orally administered, selective AT(1) receptor antagonist (losartan 50 mg) on sympathetically mediated vasoconstriction in healthy volunteers in an observer blind crossover study. Seven healthy, normotensive volunteers (21-32 years), were studied on two occasions at the end of each 6-week treatment period (losartan or placebo). Forearm blood flow (FABF) (ml/dl forearm/min) was measured by venous occlusion plethysmography during the application of lower body negative pressure (LBNP) (-20 cm H(2)O) and at the end of each incremental infusion of norepinephrine (60, 120, and 240 pmol/min). Comparison of blood flow changes was by repeated measures analysis of variance; P<0.05 was taken as statistically significant. Losartan did not alter blood pressure compared to placebo. It did significantly enhance LBNP-induced vasoconstriction in both the left arm compared to placebo (-36.6+/-3.4 vs -23.5+/-3.3%; P=0.017) and the right arm compared to placebo (-39.5+/-3.8 vs -21.0+/-3.6%; P=0.005). The FABF response to all doses of infused norepinephrine (60, 120, and 240 pmol/min) was also enhanced by losartan compared to placebo (-35.0+/-2.7 vs -18.2+/-6.0%; -43.6+/-4.3 vs -28.6+/-5.8%, and -53.9+/-3.2 vs -42.5+/-6.8%; P=0.057, respectively. Losartan enhances locally mediated sympathetic vasoconstriction in the forearm circulation of man, probably through its effect on circulating AII concentrations and we postulate that the adrenergic sympathetic constrictor action of AII is not mediated by the AT(1) receptor or is surmountable at this receptor.

Clinical trials in elderly patients.

The increasing size of the elderly population means that both the relative and absolute numbers of prescriptions for elderly patients are increasing. Depending on the age group, between 60% and 80% of elderly people are taking medication, and between 20% and 30% are taking at least three drugs. Prescribing for elderly patients as opposed to younger patients is thus ever more important. This has inevitably meant that the drug development process must increasingly recognise the importance of identifying and developing therapeutic targets relevant to older patients. Clearly, the scientific ethical and regulatory principles that determine conduct of clinical trials in younger individuals apply equally to older people. In addition, the development of drugs to be used in older patients requires an awareness of a number of physiological, pathophysiological and sociological considerations.

Effect of methionine loading on pulse wave analysis in elderly volunteers.

OBJECTIVE: To test the hypothesis that an acute increase in plasma homocysteine produced by methionine is associated with an acute increase in pulse wave velocity. DESIGN: A double blind, cross over, placebo controlled design was used and pulse wave velocity, plasma homocysteine, total cholesterol: high density lipoprotein ratio, plasma triglyceride, oxidised low density lipoprotein cholesterol concentrations, apolipoproteins A1 and B, and C reactive protein were measured between 12.5 and 20 hours after methionine loading or placebo. RESULTS: Between 12.5 and 20 hours after exposure to a methionine loading test, arterial pulse wave velocity showed no significant difference compared with placebo. At 12 hours after exposure to the methionine loading test, in the presence of a controlled diet, triglyceride concentration significantly increased by 32.6% (p<0.02), cholesterol: high density lipoprotein ratio increased significantly by 22.5% (p<0.05) compared with placebo. Simultaneously, systolic blood pressure increased significantly by 4.9% (p<0.02). CONCLUSION: In elderly volunteers, acute hyperhomocysteinaemia induced by methionine loading resulted in no overall significant delayed reduction in peripheral arterial distensibility. A significant deterioration in the lipid profile and increased blood pressure was seen during acute hyperhomocysteinaemia.

The implications of a growing evidence base for drug use in elderly patients. Part 1. Statins for primary and secondary cardiovascular prevention.

Although elderly patients represent a rapidly growing population often requiring multiple drug treatment, the evidence of effectiveness is limited for many interventions and therapies in this age group. Only during the last 30 years has a requirement to incorporate evidence into the treatment of older subjects become part of the pre- and postmarketing regulatory process in Europe and the United States. Recently, elderly patients have been shown to benefit comparably from several treatments. These studies have supported the validity of an increasingly interventional approach to disorders common in late life. However, an important issue is the applicability of the growing body of clinical trials to 'real life' patients. This is particularly true in very old (i.e. >80 years) patients and those with significant comorbidities. We review the current evidence and controversies related to the effectiveness and safety of several therapeutic strategies in cardiovascular disease (i.e. statins, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, beta-adrenoceptor blockers, and thrombolytic agents) and bone health (i.e. vitamin D and bisphosphonates).

The implications of a growing evidence base for drug use in elderly patients Part 2. ACE inhibitors and angiotensin receptor blockers in heart failure and high cardiovascular risk patients.

Traditionally, angiotensin converting enzyme (ACE) inhibitors have been used for the management of patients with congestive cardiac failure. Studies performed over the last decade have demonstrated that (1) angiotensin receptor blockers (ARBs) are as effective as ACE inhibitors in reducing morbidity and mortality in cardiac failure; and (2) inhibition of the renin-angiotensin system provides beneficial effects in patients at high cardiovascular risk without cardiac failure. This review focuses on the applicability of the results of the main trials with ACE inhibitors and ARBs to the elderly population.

The implications of a growing evidence base for drug use in elderly patients. Part 3. Beta-adrenoceptor blockers in heart failure and thrombolytics in acute myocardial infarction.

Beta-adrenoceptor blockers and thrombolytic agents are of established value in the pharmacological management of heart failure and ST-elevation myocardial infarction, respectively. However, there is uncertainty as to whether these therapeutic strategies can be safely and effectively adopted in elderly patients with comorbidities, particularly in old-old individuals. This review focuses on these trials and the age-related efficacy and safety of these drugs.

The implications of a growing evidence base for drug use in elderly patients. Part 4. Vitamin D and bisphosphonates for fractures and osteoporosis.

Fractures are common in elderly subjects, disabling and occasionally fatal. Their incidence increases exponentially with age, with the commonest affected sites being the wrist, vertebrae, hip and humerus. Of these, hip fractures are the most relevant in terms of morbidity and financial cost. The increase in fracture rate with age is believed to result predominantly from age-related increases in the incidence of osteoporosis and falls. This article reviews the evidence for the use of vitamin D and bisphosphonates for the prevention of bone fractures and osteoporosis in elderly patients.

National clinical sentinel audit of evidence-based prescribing for older people.

OBJECTIVES: To audit the performance of hospitals in evidence-based prescribing. SETTING: All hospitals in England were invited to participate. The audit was completed in 62 hospitals. SUBJECTS: Prescribing and clinical data were collected on 100 consecutive medical inpatients aged >/= 65 years at each site, enabling evaluation of eight prescribing indicators before and after intervention. The data were collected using a specifically designed database. INTERVENTIONS: The results of the first audit were available immediately from the software and a national report with locally identifiable information was returned to hospitals. Hospitals were encouraged to design and deliver their own intervention strategy. A questionnaire was sent to all hospitals to document prioritization of indicators. RESULTS: Generic names were used for 36 061 (82.6%) in 1999 and 39 188 (86.4)% in 2000. In 1999, 50% (3074) of patients had documentation of allergy status. This increased to 60% (3684) in 2000. For 21.2% of patients prescribed paracetamol in 1999 and 18.1% in 2000, the prescription was written such that it was possible to exceed the maximum recommended dose of 4 g in 24 hours. Long-acting hypoglycaemic drugs were prescribed to 29 patients in 1999 and 20 patients in 2000. Anti-thrombotics were used appropriately for 54% (520/966) of patients in atrial fibrillation in the first audit and 57% (579/1019) in the second audit. The appropriate use of aspirin increased from 91% (595/651) to 94% (725/772) and the appropriate use of benzodiazepines dropped from 49% (537/1088) to 47% (460/966) between the audits. For three indicators, the allocating of a high priority translated into a bigger improvement between the audits. CONCLUSIONS: Local ownership of data and the quality improvement process, and provision of national benchmarking data did not result in a significant improvement in prescribing in the second audit.

Optimization of drug prescribing.

The hazards of prescribing many drugs, including side-effects, drug interactions, and difficulties of compliance, have long been recognized as particular problems when prescribing for elderly people. The need for appropriate and rational prescribing for elderly patients has been prioritized in the National Service Framework for Older People. This review addresses the research evidence on epidemiology of prescribing in elderly patients, methods of measuring the quality, and the role of the prescriber and the multidisciplinary team in the day-to-day optimization of drug therapy.

Age-related changes in pharmacokinetics and pharmacodynamics: basic principles and practical applications.

Advancing age is characterized by impairment in the function of the many regulatory processes that provide functional integration between cells and organs. Therefore, there may be a failure to maintain homeostasis under conditions of physiological stress. The reduced homeostatic ability affects different regulatory systems in different subjects, thus explaining at least partly the increased interindividual variability occurring as people get older. Important pharmacokinetic and pharmacodynamic changes occur with advancing age. Pharmacokinetic changes include a reduction in renal and hepatic clearance and an increase in volume of distribution of lipid soluble drugs (hence prolongation of elimination half-life) whereas pharmacodynamic changes involve altered (usually increased) sensitivity to several classes of drugs such as anticoagulants, cardiovascular and psychotropic drugs. This review focuses on the main age-related physiological changes affecting different organ systems and their implications for pharmacokinetics and pharmacodynamics of drugs.

Stroke, dementia, and drug delivery.

Stroke and dementia represent a major health burden for elderly subjects as they are associated with significant morbidity and mortality. The rates of stroke and dementia are progressively increasing due to the ageing population in most westernized countries. Therefore, both these conditions represent a major therapeutic target. However, the therapeutic options available for the management of stroke and dementia remain largely unsatisfactory, the main reason being the difficulty in transferring the results obtained in animal and in vitro studies to the clinical setting. This review focuses on the recent advances in pathophysiology and treatment of these conditions and future directions for research. Moreover, the technique of functional magnetic resonance imaging is discussed in detail as a tool to assess the effects of therapeutic agents on the central nervous system and monitor the progression of diseases. Finally, an overview of the issue of drug delivery into the central nervous system is presented.

Disposition of flurbiprofen in man: influence of stereochemistry and age.

1. The stereoselective metabolism and pharmacokinetics of the enantiomers of flurbiprofen were investigated following the oral administration of the racemic drug (100 mg) to four young and four elderly healthy volunteers (two males and two females per group). 2. The stereochemical composition of the drug and the 4'-hydroxy- metabolite in serum and the drug, 4'-hydroxy- and 3'-hydroxy-4'-methoxy- metabolites, both free and conjugated, in urine were determined by a direct chromatographic method of enantiomeric analysis. 3. Modest enantioselectivity in clearance (CL S/R: young, 0.86; elderly, 0.88) was largely responsible for the apparent elimination half-life of (S)-flurbiprofen being significantly greater (p<0.01) than that of the R-enantiomer in both age groups (young, S: 5.2 +/- 0.7 versus R: 4.5 +/- 0.6 h; elderly, S: 9.6 +/- 1.2 versus R: 7.1 +/- 1.0 h). The serum concentrations of 4'-hydroxyflurbiprofen were five- to 20-fold lower than those of the corresponding drug enantiomers, stereoselective disposition being evident in the significantly greater (p<0.05) apparent half-lives of the S- compared with the R-enantiomer in both groups (young, S: 10.6 +/- 2.4 versus R: 6.7 +/- 1.1 h; elderly, S: 13.7 +/- 1.7 versus R: 10.2 +/- 1.2 h). 4. Some 60 and 72% of the dose was excreted in 24-h urine in elderly and young volunteers, respectively, a significantly greater (p<0.05) proportion of which was of the R-configuration in both age groups (S/R: young, 0.87; elderly, 0.81). The major urinary excretion products were flurbiprofen and 4'-hydroxyflurbiprofen, and their acyl-conjugates in both groups. 5. Age-associated differences in the pharmacokinetics of flurbiprofen occurred in a non-stereoselective manner and were primarily as a consequence of a significant approximately 40% decrease (p<0.01) in clearance of both enantiomers in the elderly due to reduced metabolic activity. Consequently, the elderly had greater exposure to both enantiomers, as reflected by the AUCs(0-inf) being significantly higher (p<0.05), by 60%, in this age group compared with the young. 6. The findings suggest that age-related alterations in the disposition of flurbiprofen could have significant implications for the use of the drug in the elderly.

A refractory case of vasovagal syncope treated with theophylline.

We report the case of a 23 year-old female with neurocardiogenic syncope refractory to treatment with other agents who responded to theophylline. Despite inconsistent clinical trial evidence to support its use, theophylline may prove useful in individual cases.

Predictors of falls in a high risk population: results from the prevention of falls in the elderly trial (PROFET).

OBJECTIVES: The prevention of falls in the elderly trial (PROFET) provides evidence of the benefits of structured interdisciplinary assessment of older people presenting to the accident and emergency department with a fall. However, the service implications of implementing this effective intervention are significant. This study therefore examined risk factors from PROFET and used these to devise a practical approach to streamlining referrals from accident and emergency departments to specialist falls services. METHODS: Logistic regression analysis was used in the control group to identify patients with an increased risk of falling in the absence of any intervention. The derived predictors were investigated to see whether they also predicted loss to follow up. A second regression analysis was undertaken to test for interaction with intervention. RESULTS: Significant positive predictors of further falls were; history of falls in the previous year (OR 1.5 (95%CI 1.1 to 1.9)), falling indoors (OR 2.4 (95%CI 1.1 to 5.2)), and inability to get up after a fall (OR 5.5 (95%CI 2.3 to 13.0)). Negative predictors were moderate alcohol consumption (OR 0.55 (95%CI 0.28 to 1.1)), a reduced abbreviated mental test score (OR 0.7 (95%CI 0.53 to 0.93)), and admission to hospital as a result of the fall (OR 0.26 (95%CI 0.11 to 0.61)). A history of falls (OR 1.2 (95%CI 1.0 to 1.3)), falling indoors (OR 3.2 (95%CI 1.5 to 6.6)) and a reduced abbreviated mental test score (OR 1.3 (95%CI 1.0 to 1.6)) were found to predict loss to follow up. CONCLUSIONS: The study has focused on a readily identifiable high risk group of people presenting at a key interface between the primary and secondary health care sectors. Analysis of derived predictors offers a practical risk based approach to streamlining referrals that is consistent with an attainable level of service commitment.

The cardiovascular system.

The ageing process is associated with important changes in the responses of the cardiovascular system to pharmacological stimuli. They are not limited to the arterial system, involved in the modulation of cardiac afterload and vascular resistance, but they also involve the low-resistance capacitance venous system and the heart. The main changes include loss of large artery compliance, dysfunction of some of the systems modulating resistance vessel tone, increased activity of the sympathetic nervous system, and reduced haemodynamic responses to inotropic agents. This review focuses on the effects of ageing on arterial and venous reactivity to drugs and hormones, the autonomic nervous system, and the cardiovascular responses to inotropic agents. Some of the age-related changes might be at least partially reversible. This may have important therapeutic implications.