When people hear the word "dementia" they may think of Alzheimerdisease (AD). While Alzheimer dementia is the most common typeof dementia, it is not the only type. In general, dementia isa decline in thinking that most often includes problems withmemory (see About Dementia). Most dementias come on slowly andworsen steadily. When someone gets the diagnosis of dementia,a cure is only very rarely possible (see p2 About ReversibleDementias).
In the current issue of Neurology, Sacks and Shulman1 reportone of these rare cases of a reversal of dementia involvinga patient on steroid medication. They describe a man with apainful muscle condition who was being treated with the corticosteroiddrug, prednisone (a powerful medication used especially to decreaseinflammation). His problems began with a change in his behaviorand memory while he was traveling. He was admitted to a localhospital where he was described as "grandiose and disinhibited."When he admitted that he had been purposely overdosing himselfon his prednisone, his physicians put him back on the low doseoriginally intended. But, he remained confused and did not returnto his former self. Several months later, the man had a thoroughevaluation for persistent problems with his thinking. That evaluationled to the conclusion that he had a dementia due to a degenerativedisease, perhaps AD. It was thought that the high-dose prednisonemight have unmasked the AD and hastened its appearance. He continuedto worsen over the next several months. Then, a new neurologistrecommended that the prednisone be stopped completely. At thatpoint the man began to improve dramatically.
It is well known that high-dose corticosteroids, like prednisone,can cause agitation or even a manic state.2 In this man's case,even the low-dose therapy seemed to be bothering his thinking.Previous experience with the effect of prednisone on thinkingshowed that when the drug is stopped, there may be a lag periodof months before improvement occurs. For this man, it was notuntil the prednisone was stopped completely that his recoverybegan.
The message that Sacks and Shulman wanted to convey to neurologistswas that even low doses of prednisone can cause confusion. Acareful reader might question the certainty that it was theprednisone that caused this man's problem. There was no bloodtest or brain scan that proved that the prednisone was responsible.The case for blaming prednisone was based on the very high doseshe received. Also, the parallels in time between when he receivedprednisone and when he was ill pointed to the prednisone asthe cause of his confusion. To a neurologist, however, theremay be other explanations for this man's illness. Perhaps hehad a brain infection or some other acute neurological disorderthat wasn't detected when he was first diagnosed. In this case,his delayed recovery just happened to coincide with stoppingthe prednisone. Or possibly, there were two problems. First,the overdosage of prednisone occurred. Then, second, side effectsof the medications that were started to treat his behavior appearedand led to his prolonged difficulties. For example, it is wellknown that risperidone (which is used to treat psychotic behavior)can cause stiffness and slowing down. Then, valproic acid (whichmay be used as a mood stabilizer) can make a person drowsy andconfused if the dose is too high. So, was it the prednisoneor not? We will never know for certain what really caused hiscondition.
For the 7 or 8 months of his confusional state, it was obviouslymiserable for him and his family. Fortunately, there was a happyending. What are the lessons to be learned? The physicians whoinitially evaluated the man performed the proper set of tests,but they followed conventional wisdom that low doses of prednisonedo not cause problems with thinking. Perhaps, as Sacks and Shulmansuggest, that view needs to be reconsidered. But, equally important,how could this man have taken five times the prescribed dosefor some extended period of time without someone like his pharmacistor physician recognizing it? Patients who adjust their own medicationswithout talking to their doctor run a big risk of illness dueto the medication itself (or not getting the desired effectif they decrease the drug on their own). This is really a keymessage in this whole story. Changes in thinking and behavior,especially when relatively sudden, must always be explored;they may be reversible.
Dementia is the loss of mental abilities over a period of time.People with dementia may be confused and not able to rememberthings. They may have difficulty especially learning new thingsor remembering names of people they have just met. They mayget lost in places that were previously very familiar. Theymay have difficulty finding words. Usually these problems comeon gradually and are often missed early on by family and friends.Eventually they may have problems performing normal daily activitiesbecause they lose skills they once had. Their behavior may alsochange; they may become suspicious or irritable when they can'tdo a task.
In contrast to dementia, sometimes people rapidly develop confusionand changes in thinking. Neurologists use the term "delirium"for this condition that is often reversible. The typical symptomsof delirium and dementia overlap quite a bit, but can usuallybe distinguished over time. Often the cause of delirium canbe found and treated.
Discovery of a reversible condition in someone with dementiais rather uncommon in usual practice.3 In the case reportedby Sacks and Shulman1 in this issue of Neurology, a man becameconfused when on a high dose of the corticosteroid, prednisone.After he failed to improve when the dose was lowered, it waspresumed that he had an underlying dementia. This man's caseis being reported precisely because his delayed improvementwas so unusual.
There are many medications besides prednisone that can affectthinking and memory. Medications for pain, sleep, and anxiety,for example, can all easily make a person slow down mentally.For this reason there are usually warning labels against drivingor using dangerous equipment. Heart medication such as digitalisor propranolol, and medications to treat seizures and depression,also can affect thinking. To be sure, these medications usuallydo not cause confusion when taken at the proper dose. Becauseevery person is unique, it isn't always possible to know theright dose initially. Also, in older people, drugs are processedmore slowly in the body and so a much lower dose may be needed.
There are other psychiatric, medical and neurological conditionsthat may mimic dementia. Depression is a condition that is frequentlyaccompanied by poor concentration, poor attention span, andpoor memory. People with depression will often complain constantlyabout their memory and also about feeling sad, blue, or "downin the dumps." However, on occasion, some people who are depressedbecome so apathetic that they stop complaining about the depressionand might be falsely labeled as demented. It is important torecognize depression because it can be treated successfully.
A wide variety of altered levels of blood chemistry, hormones,or nutrients can cause dementia. These include altered bloodcount and poor kidney or liver function. Major declines in levelsof thyroid hormone or vitamin B12 in the blood can also causedementia. These are all easy to diagnose with inexpensive bloodtests and can be treated.
A condition known as normal pressure hydrocephalus can alsomimic dementia. Normal pressure hydrocephalus is a rare buttreatable condition that produces a distinctive problem in walking,poor bladder control, and dementia. A head CT or MR scan showsballooning of the brain ventricles (the fluid-filled inner cavitiesof the brain) out of proportion to the apparent shrinkage ofthe brain itself. In appropriate patients, a tube can be placedsurgically inside the brain ventricles to drain excess cerebrospinalfluid. If the surgery is done early enough many of the problemsof walking, bladder control and thinking can be reversed.
The result of a head injury, even relatively mild, can mimicdementia. A fall or bumping the head may cause blood clots toform between the inner side of the skull and the brain (calleda subdural hematoma). In older people, the injury can be quitemodest and even forgotten. Removal of the subdural hematomaby surgery can cure the symptoms of memory loss. Subdural hematomascan be diagnosed with certainty only with CT scans or MR scans,which is why the American Academy of Neurology recommends thatall patients with suspected dementia have one of these brainscans at the time of the initial evaluation by a doctor.4
So, when a person develops confusion, especially if the symptomscome on over a short period of time (that is, days or weeks),family and physicians must consider the various possible causesfor the problem. Part of the evaluation involves laboratorytests, but one critical part is finding out about all medicationsand all health problems that the person has. Often, the solutionwill appear after a careful retelling and analysis of the onsetand progression of the problems.
Sacks O, Shulman M. Steroid dementia: an overlooked diagnosis? Neurology 2004;64:707–709.
Wolkowitz OM, Reus VI, Canick J, Levin B, Lupien S. Glucocorticoid medication, memory and steroid psychosis in medical illness. Ann N Y Acad Sci 1997;823:81–96.[Medline]
Clarfield AM. The decreasing prevalence of reversible dementias: an updated meta-analysis. Arch Intern Med 2003;163:2219–2229.[Abstract/Free Full Text]
Knopman DS, DeKosky ST, Cummings JL, et al. Practice parameter: diagnosis of dementia (an evidence-based review). Neurology 2001;56:1143–1153.[Abstract/Free Full Text]
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What is dementia?
What is delirium?
