The effects of commonly prescribed drugs in patients with Alzheimer's disease on the rate of deterioration

Homocysteine as a predictor of cognitive decline in Alzheimer's disease

OBJECTIVE

Moderately elevated levels of plasma total homocysteine are associated with an increased risk of developing Alzheimer's disease. We have tested whether baseline concentrations of homocysteine relate to the subsequent rate of cognitive decline in patients with established Alzheimer's disease (AD).

METHODS

In 97 patients with AD, 73 pathologically-confirmed, we analysed the decline of global cognitive test scores (CAMCOG) over time from the first assessment for at least three 6-monthly visits up to a maximum of 9.5 years (in total 689 assessments). Non-linear mixed-effects statistical models were used.

RESULTS

Baseline homocysteine levels showed a concentration-response relationship with the subsequent rate of decline in CAMCOG scores: the higher the homocysteine, the faster the decline. The relationship was significant in patients aged < 75 years who had not suffered a prior stroke. For example, in patients aged 65 years with a baseline homocysteine of 14 micromol/L, the decline from a CAMCOG score of 88 to a score of 44 occurred 19.2 (95% CI 6.8, 31.6) months earlier than in patients with a baseline homocysteine of 10 micromol/L.

CONCLUSIONS

Raised homocysteine concentrations within the normal range among the elderly strongly relate to the rate of global cognitive decline in patients with Alzheimer disease. Plasma homocysteine can readily be lowered by B-vitamin treatment and trials should be carried out to see if such treatments can slow the rate of cognitive decline in relatively young patients with Alzheimer disease.

Potentially inappropriate medication use in older adults with mild cognitive impairment

BACKGROUND

Patients with mild cognitive impairment (MCI) may be especially vulnerable to the side effects of potentially inappropriate medications (PIMs), especially those that impair cognition.

METHODS

We conducted a cross-sectional study to determine the prevalence of PIM use among 689 patients with MCI. We used the 2003 Beers Criteria for cognitive impairment to identify PIMs. We then determined if certain patients were more likely to use PIMs.

RESULTS

There were 143 (20.8%) patients with MCI taking a PIM: 108 (15.7%) patients were taking one PIM and 35 (5.1%) patients were taking two or more PIMs. The most common PIMs were anticholinergics (35.7%) and benzodiazepines (31.5%). Patients were more likely to be taking PIMs if they were women and were taking a greater number of medications and less likely if they had a history of myocardial infarction.

CONCLUSIONS

Patients with MCI are frequently taking PIMs that may negatively affect cognition. Future research is needed to assess whether cognitive impairment symptoms are improved if PIM use is reduced.

Changes in utilisation of anticholinergic drugs after initiation of cholinesterase inhibitors

PURPOSE

Cholinesterase inhibitors (CEIs) have been subsidised in Australia since February 2001 for cognitive decline associated with mild to moderate Alzheimer disease. The number of people with Alzheimer disease is expected to increase, with a continuing increase in the number of people receiving CEI's. Many anticholinergic drugs (ACDs) are also prescribed to people receiving CEIs and concerns about the impact of the interaction have been raised. The aim of this study was to describe co-prescribing of a group of important ACDs in patients initiating treatment with CEIs in Australia.

METHODS

Pharmacy claim data for Australia (Pharmaceutical Benefits Scheme) was examined for the period 1 April to 30 June 2006. All selected prescriptions supplied for patients receiving their first supply of any CEIs (initiators) were extracted for 14 weeks prior to and post the first date of supply. The numbers of initiating people co-administering CEIs and ACDs was examined.

RESULTS

5797 persons received their first prescription for CEIs between 1 April and 30 June 2006. Thirty-two per cent of these also received prescriptions for at least one ACD. There was a statistically significant increase in the number of initiators receiving an ACD. The significant increase was in patients receiving atypical antipsychotics. There was a trend towards an increase in patients receiving oxybutynin.

CONCLUSIONS

Extent of co-administration of ACDs and CEIs is similar to other international studies however the most significant increase is seen in patients receiving atypical antipsychotics. The implications of adding atypical antipsychotics are potential for worsening disease, increasing adverse effects and increased health resource utilisation in this vulnerable group.

The brain RAS and Alzheimer's disease

Alzheimer's disease (AD) has become a major world-wide health problem with ever rising costs associated with the treatment and care of afflicted individuals. As life expectancy has increased the occurrence of dementia has also increased. Hypertension during middle adulthood is correlated with a significantly elevated risk of cognitive impairment later in life. Treatment with antihypertensive drugs, particularly angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), has been reported to reduce the likelihood and slow the progression of AD; however, the use of ACE inhibitors may be accompanied by an increase in amyloid beta protein(1-42) accumulation. This review summarizes available information regarding the brain renin-angiotensin system (RAS), and specifically the efficacy of ACE inhibitors as anti-dementia agents, and considers the recently discovered AT(4) receptor and associated agonist drugs as potential new therapeutic targets to treat memory impairments associated with AD. We conclude with a description of recent efforts by members of our laboratory to develop blood-brain barrier penetrant angiotensin IV analogue drugs that facilitate cognition in animal models of AD. These efforts have resulted in a small molecule with desirable hydrophobicity characteristics that shows promise with respect to memory facilitation when peripherally administered.

The angiotensin AT4 receptor subtype as a target for the treatment of memory dysfunction associated with Alzheimer's disease

Over recent years antihypertensive drugs, particularly angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), have been reported to have beneficial effects upon cognitive impairment. Such findings suggest that pharmacological manipulation of angiotensin ligands may be of clinical importance in slowing or halting the cognitive deterioration seen in vascular dementia and Alzheimer's disease. The mechanism(s) underlying these improvements in cognitive function remains unclear; however, important leads are emerging. The angiotensin AT4 receptor subtype, discovered by our laboratory in 1992, influences several important behaviours and physiologies, including learning and memory, and may play a role in this cognitive improvement. This review initially describes the therapeutic drugs approved by the Federal Drug Administration and new approaches presently being developed to treat Alzheimer's disease-induced cognitive impairment. Next, the biologically-active angiotensin ligands and their respective receptor subtypes are discussed, followed by the roles of angiotensin II, angiotensin IV, ACE inhibitors and ARBs in cognitive function. We conclude with a working hypothesis concerning the importance of the AT4 receptor subtype as a new potential drug target for the treatment of Alzheimer's disease-associated memory loss.

A preliminary study of anticholinergic burden and relationship to a quality of life indicator, engagement in activities, in nursing home residents with dementia

OBJECTIVES

(1) To describe the anticholinergic burden experienced by nursing home residents with dementia using the Anticholinergic Cognitive Burden (ACB) Scale; and (2) to determine the association of anticholinergic burden and engagement in activity.

DESIGN

Cross-sectional, using baseline data from an ongoing clinical trial.

SETTING

Nine nursing homes in Pennsylvania.

PARTICIPANTS

Eighty-seven nursing home residents with dementia

MEASUREMENTS

The ACB Scale was used to classify the severity of each resident's prescribed drugs' anticholinergic activity on cognition. Engagement in activity was measured by direct observation using a standard instrument.

RESULTS

Across 775 observations, subjects were active approximately 54% of the time, doing nothing 24% of the time, and asleep over 21% of the time. Seventy-one (81.6%) subjects were prescribed at least one drug with anticholinergic properties and 32 (36.7%) were prescribed at least one drug with severe anticholinergic properties. On average, subjects had a total ACB score of 2.55 (+/- 1.9). Mental status (MMSE) and dependency (PGDRS) were associated with engagement, but use of anticholinergic drugs was not.

CONCLUSION

Nursing home residents are prescribed many drugs with anticholinergic properties. The ACB Scale has utility as a tool to alert practitioners to high anticholinergic burden, who can then use this information when choosing between equally efficacious medications. Further study using larger samples of persons with dementia in earlier stages of the disease, and use of intense measurement designs are needed to more clearly determine the association of ACB with quality of life indicators.

Effects of hypertension therapy based on eprosartan on systolic arterial blood pressure and cognitive function: primary results of the Observational Study on Cognitive function And Systolic Blood Pressure Reduction open-label study

BACKGROUND

Recent studies have indicated a relationship between hypertension and cognitive function but therapeutic trials of antihypertensive therapy on the prevention of cognitive disorders have produced controversial findings.

METHODS

The Observational Study on Cognitive function And Systolic Blood Pressure Reduction is an open-label trial in 28 countries designed to evaluate the impact of eprosartan-based therapy on cognitive function. The Mini-Mental State Examination was used as a global tool for the comprehensive assessment of cognitive function, with an intention to treat a cohort of 25 745 hypertensive patients aged at least 50 years during a follow-up interval of 6 months. Blood pressure therapy was initiated with eprosartan 600 mg/day with provision for additional medication to be introduced after 1 month in patients with insufficient blood pressure response.

RESULTS

Use of eprosartan, either as monotherapy or in combination regimens, was associated with a substantial reduction in arterial blood pressure from 161.9/93.1 mmHg at baseline to 136.1/80.8 mmHg at 6 months (P < 0.0001). The overall mean Mini-Mental State Examination score at completion of follow-up was 27.9 +/- 2.9 compared with 27.1 +/- 3.4 at baseline (P < 0.0001). A significant correlation was shown between the mean absolute response of Mini-Mental State Examination and the magnitude of systolic blood pressure reduction. At the end of the study, patients with systolic blood pressure less than 140 mmHg had a larger improvement in Mini-Mental State Examination [0.88 +/- 0.01 (SEM)] than those with systolic blood pressure between 140 and 159 mmHg [0.69 +/- 0.02 (SEM); P < 0.001], or than those with systolic blood pressure of at least 160 mmHg [0.38 +/- 0.05 (SEM); P < 0.0001]. Furthermore, cognitive decline was demonstrated in multiple linear regression to be independently associated with age [odds ratio 1.19 (1.14; 1.25)], Mini-Mental State Examination at baseline [odds ratio 1.19 (1.14; 1.25)], systolic blood pressure at baseline [odds ratio 1.20 (1.13; 1.27)] and systolic blood pressure reduction [odds ratio 0.77 (0.73; 0.82)].

CONCLUSION

The results of the Observational Study on Cognitive function And Systolic Blood Pressure Reduction are supportive of the proposition that antihypertensive therapy based on drugs that target the renin-angiotensin system is associated with preservation of cognitive function.

Geropharmacology: a primer for advanced practice. Acute care and critical care nurses, part II

In the first part of this 2-part continuing education series, sources of medication errors were discussed. A predominant source of errors was the prescribing of potentially inappropriate medications for older adults. In this second part, drug classifications and drugs posing problems for older adults and cautions for advanced practice acute care and critical care nurses in their medication therapy management are highlighted. Cautions are advanced for anticholinergics, antihypertensives, analgesics, and psychotropics because of the severity of adverse reactions, including anticholinergic symptoms; mental status changes (especially confusion, sedation, delirium, and cognitive impairment); orthostatic hypotension; gastrointestinal tract problems (especially hemorrhage); depression; and neurobehavioral disturbances (agitation and aggressiveness). Risks of life-threatening outcomes associated with medications and adverse reactions are highlighted.

Dementia of the Alzheimer type

Dementia of the Alzheimer type is a progressive, fatal neurodegenerative condition characterized by deterioration in cognition and memory, progressive impairment in the ability to carry out activities of daily living, and a number of neuropsychiatric symptoms. This narrative review summarizes the literature regarding descriptive epidemiology, clinical course, and characteristic neuropathological changes of dementia of the Alzheimer type. Although there are no definitive imaging or laboratory tests, except for brain biopsy, for diagnosis, brief screening instruments and neuropsychiatric test batteries used to assess the disease are discussed. Insufficient evidence exists for the use of biomarkers in clinical practice for diagnosis or disease management, but promising discoveries are summarized. Optimal treatment requires both nonpharmacological and pharmacological interventions, yet none have been shown to modify the disease's clinical course. This review describes the current available options and summarizes promising new avenues for treatment. Issues related to the care of persons with dementia of the Alzheimer type, including caregiver burden, long-term care, and the proliferation of dementia special care units, are discussed. Although advances have been made, more research is needed to address the gaps in our understanding of the disease.

A feasibility and tolerability study of lithium in Alzheimer's disease

OBJECTIVE

To assess the safety and feasibility of prescribing long term lithium to elderly people with mild to moderate Alzheimer's disease (AD).

METHODS

An open label treatment group with low dose lithium for up to 1 year with the Lithium Side Effects Rating Scale as the primary outcome measure. A comparison group matched for cognition and age not receiving lithium therapy.

RESULTS

Twenty-two people with AD initiated lithium. Fourteen participants discontinued therapy after a mean of 16 weeks of treatment compared to the 39 weeks for those continuing to take treatment at the end of the study. Three patients discontinued treatment due to possible side effects that abated on ceasing therapy. The reports of side effects on the primary outcome scale did not differ between those discontinuing therapy and those remaining in the study. Two patients died whilst receiving lithium--in neither case was the treatment felt to be related to cause of death. There was no difference in deaths, drop outs or change in MMSE between those receiving lithium and the comparison group.

CONCLUSIONS

Lithium treatment in elderly people with AD has relatively few side effects and those that were apparently due to treatment were mild and reversible. Nonetheless discontinuation rates are high. The use of lithium as a potential disease modification therapy in AD should be explored further but is not without problems.

Angiotensin converting enzyme inhibitors and cognitive and functional decline in patients with Alzheimer's disease: an observational study

We previously reported that angiotensin converting enzyme inhibitors (ACEIs) decrease the rate of cognitive decline in elderly patients with hypertension, but their impact on patients with Alzheimer's disease (AD) is not known. A total of 62 elderly patients with AD were enrolled, and 52 completed the study for 6 months. Mini-Mental Status Examination (MMSE), Clock Draw Test (CDT), working memory (Digit Ordering), Instrumental Activities of Daily Living (IADL) scale, and the Screen for Caregiver Burden (SCB) were collected at baseline, 3 months, and 6 months. AD patients receiving ACEI (N = 15) demonstrated a slower rate of decline in digit forward (P = .003) and IADL scale (P = .003) and an improved measure of caregiver burden (P = .04) but not MMSE (P =.15) or CDT (P =.9) compared with those not receiving ACEI after adjusting for other risk factors. This study suggests that use of ACEI in AD patients is associated with slower rate of AD progression. A randomized clinical trial is needed to confirm our finding.

CNS-active drugs in aging population at high risk of cerebrovascular events: evidence from preclinical and clinical studies

The recovery process following cerebral insults such as stroke is affected by aging and pharmacotherapy. The use of medication including CNS-active drugs has increased in the elderly during recent years. However, surprisingly little is known about how safe they are with respect to severity of sensorimotor and cognitive impairments or recovery of function following possible cerebrovascular accidents. This review examines the experimental and clinical literature, primarily from 1995 onwards, concerning medication in relation to cerebrovascular events and functional recovery. Special attention is directed to polypharmacy and to new CNS-active drugs, which the elderly are already taking or are prescribed to treat emerging, stroke-induced psychiatric symptoms. The neurobiological mechanisms affected by these drugs are discussed.