Does statin use decrease the amount of Alzheimer disease pathology in the brain?
Lisa C. Silbert, MD, MCR
In this issue of Neurology®, Li and coauthors1 report theresults of a study that looked at differences in the numberof plaques and tangles in the brain at death between those whoused statins (see below) and those who did not. Patients withAlzheimer disease (AD) develop clusters of protein in betweenthe brain cells, called amyloid plaques, and groups of fibersinside of brain cells, called neurofibrillary tangles (figure).
Figure Drawing of tissue from a normal brain and one with Alzheimer disease
Note that the Alzheimer disease brain has amyloid plaques and neurofibrillary tangles. Illustration courtesy of Alzheimers Disease Research, a program of the American Health Assistance Foundation.
Statins are a type of medication commonly used to treat highcholesterol. They have been shown to lower the risk of heartattack and stroke in people with a history of heart disease.2Besides lowering cholesterol levels, statins may also help tolower the amount of swelling, free radicals, and small arterydisease in the brain. Some researchers have seen that the numberof people who get AD is lower among those taking statins thanthose not taking statins. Recent research has not shown thatstatin use prevents the development of AD.
All the patients in this study were followed in the Adult Changesin Thought (ACT) study with regular screening tests for dementia.Although none of the subjects had problems with their thinkingwhen they entered the study, some developed dementia beforethey died. When the authors began this study, 608 people takingpart in the ACT study had died. The rate of death was lowerin statin users than in nonusers. Of the 608 subjects who died,110 of those had agreed to an examination of their brain atthe time of their death. These 110 subjects tended to be olderat death, and were more likely to be female and white than thosewho did not wish to participate. Thirty-six of the 110 subjectshad been treated with a statin at some time in their life, and74 had not. An equal percentage of subjects in each group developeddementia before death.
The amount of plaques and distribution of tangles in the brainwere compared between those who had taken statins and thosewho had not. The authors also considered other things that mightinfluence the amount of plaques and tangles, such as age atdeath, gender, level of thinking ability at the beginning ofthe study, brain weight, and the presence of small strokes.
The main finding is that statin users were less likely to havea high degree of tangles in their brain at death than nonusers.The amount of plaques was not different between the two groups.Statin users were less likely to have the degree of both plaquesand tangles typically seen in AD than the nonusers. However,the authors also report that because of differences in characteristicsbetween those who agreed to brain examination at death and thosewho did not, and because of differences in the rate of deathbetween statin users and nonusers, it is difficult to applythese results to the general, living population.
AD affects approximately 4.9 million people age 65 and olderin the United States, with the number expected to rise to 7.7million by 2030.3 Besides causing suffering to those affectedand their caregivers, AD creates a high financial burden tofamily members and society. Right now there is no cure for AD.Drugs used to treat AD help with symptoms of the disease, butdo not help the underlying causes. Studies looking at the effectsof medicine on what is actually happening in the brain tissueare rare, and are extremely valuable, as we search for treatmentsto slow down or reverse the disease process.
This study shows that people who use a statin drug at some pointin their life may have fewer brain tangles, a hallmark of AD,at death. Although the results of this study are promising,it has not yet been shown that statin use directly decreasesAD pathology or delays the clinical manifestation of the diseasein living people.
Alzheimer disease (AD) is a progressive illness in which patientshave dementia, which means having memory loss and problems thinkingthat are bad enough to interfere with day-to-day functioning.Patients with AD develop clusters of protein in between thebrain cells, called amyloid plaques, and groups of fibers insideof brain cells, called neurofibrillary tangles. About 24 millionpeople have dementia in the world, with the number expectedto rise to 81 million by 2040. AD is the most common cause ofdementia, and accounts for 50 to 60% of all cases.
WHAT IS THE RELATIONSHIP BETWEEN CHOLESTEROL AND AD?
At this time, no one knows for sure what role cholesterol playsin AD. All of us need some cholesterol in our diet in orderto keep the cells in our body healthy. However, it has beenshown by some researchers that animals given a high cholesteroldiet develop greater than normal levels of a protein calledß-amyloid (Aß). In AD, Aß buildsup in the brain to form amyloid plaques. Animals given a drugto lower their cholesterol level had a decrease in the amountof these plaques. In humans with high cholesterol, some studieshave shown an increased risk of getting AD, while other studieshave shown a decreased risk of getting AD.4
The following portion of the ABOUT page is adapted from JankowiakJ. Depression may be another risk for Alzheimers dementia:your doctor can help. Neurology 2002;59:E4–E5.
WHAT ARE THE SYMPTOMS?
Loss of recent memories is usually the earliest warning. Forinstance, the person will repeat stories in the same conversation.Other features include:
Misplacing belongings
Difficulty doing familiar tasks
Increasingconfusion and disorientation to time and place
Trouble findingwords, not following conversations
Changes in mood or behavior
Changes in personality
Poor or decreased judgment
Lossof initiative
KNOW THE WARNING SIGNS
Unfortunately, in early stages, many people fail to recognizethat something is wrong. They may assume that such behavioris a normal part of getting older. It is not. Symptoms may developgradually and go unnoticed for a long time. Sometimes familiesdo not act even when they suspect something is wrong. The keyis early diagnosis. It is critical to see a doctor when yourecognize or suspect AD symptoms.
HOW IS AD DIAGNOSED?
When AD is suspected, it is important to have a complete medicaland neurologic workup. The purpose of this evaluation is touncover other causes of dementia that must be treated in veryspecific ways. This may include:
A complete health history and physical examination
Screeningfor depression
Neurologic and mental status testing
Bloodand urine tests
CT scan or MRI
WHAT CAUSES AD?
The cause of AD is not fully known. It is not contagious. Agingand inherited or genetic factors seem to play an important role.The most common form of AD does not run in families.
WHAT ARE THE TREATMENTS?
Although there is currently no cure for AD, there are treatmentsthat may help.
Treat memory symptoms.
The cognitive symptoms of AD should be treated as early as possibleto slow the progression of the disease. Drugs called cholinesteraseinhibitors may be considered in patients with mild to moderatedisease. Vitamin E may also slow the progression, but shouldonly be used if prescribed by the doctor.
Treat behavioral problems.
Suspiciousness, aggression, or resistance to care may be treatedfirst by understanding what triggers these behaviors. Caregiversmay learn how to change things in the environment to improvecooperation. Some examples include providing low lighting andmusic to improve eating behaviors, taking regular walks, schedulingtoileting, and following consistent routines. Certain medicationsmay also help, including drugs to treat depression.
Caregivers need caring too.
Caregiver training programs to learn more about the diseaseand how to manage it help delay the time to nursing home placement.Support systems (adult day care, computer support networks,telephone support programs, and other respite programs) mayalso help.
PREVENTION
Although there is no known way to prevent AD, researchers believethere are several things that will help keep your brain healthy:
Avoid harmful substances—excessive drinking and drug abuseare thought to damage brain cells.
Challenge yourself—readfrequently, do crossword puzzles.Keep mentally active. Learnnew skills. This strengthens thebrain connections and promotesnew ones.
Exercise regularly—even low–moderatelevel activitysuch as walking or gardening three to five timesper week canmake you feel better.
Stay socially active—family,friends, church, and a senseof community may all contributeto better brain health.
CAREGIVER HEALTH
Families and friends can help by recognizing that AD impactsnot only the patient, but also the primary caregiver. To takethe best care of the patient with AD, the primary caregivermust take care of himself or herself. He or she should be encouragedto learn more about the disease, avoid isolation, and seek supportfrom family, friends, and professionals.
Li G, Larson EB, Sonnen JA, et al. Statin therapy is associated with reduced neuropathologic changes of Alzheimer disease. Neurology 2007;69:878–885[Abstract/Free Full Text]
Fletcher GF, Bufalino V, Costa F, et al. Efficacy of drug therapy in the secondary prevention of cardiovascular disease and stroke. Am J Cardiol 2007;99:1E–35E.[Medline]
Sjogren M, Mielke M, Gustafson D, Zandi P, Skoog I. Cholesterol and Alzheimers disease—is there a relation? Mech Ageing Dev 2006;127:138–147.[Medline]