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Medications that cause memory loss

December 28, 2011
By Mary Lou Williams, M. Ed. , Fort Myers Beach Bulletin, Fort Myers Beach Observer

Case studies of two supercentenarians

Edna Parker turned 115 years old in April 2008. At that time she was recognized by Guinness World Records as the world's oldest known person. She died very soon thereafter. A group of scientists had been evaluating her performance since she was 112 years old and performed full pathological examination of her body immediately after her death. The psychological tests revealed that her general performance was above the average of healthy adults of 60-75 years. Her brain showed almost none of the changes associated with Alzheimer's disease. Counts of the number of neurons corresponded with the number of nerve cells found in the brains of healthy people 60-80 years old. The study was published in the June 3, 2008, issue of Neurobiology of Aging. The lead researcher was Gert Holstege. The researchers concluded: "Our observations indicate that the limits of human cognitive function extend far beyond the range that is currently enjoyed by most individuals and that brain disease, even in supercentenarians, is not inevitable."

In February 1995, Dr. Karen Ritchie, a neurobiologist, published a similar study in the British Journal of Psychiatry. She examined the mental status of a woman who was 118 years and 9 months, the oldest living person at the time. Dr. Ritchie's conclusion: "The subject shows no evidence of progressive neurological disease." The subject's name was Jeanne Calment. Jeanne Calment died at the age of 122 years. She is presently considered to have had the longest authenticated life-span in the history of the human species.

When Dr. Ritchie first saw Jeanne Calment, she was being given a fairly popular heart medicine, not because she had a problem but because it was fashionable at the time to do so preventively. When Dr. Ritchie asked that the medicine be withdrawn because there was really no reason for Ms. Calment to be taking it, there suddenly was a huge upturn in the subject's cognitive functioning. The medicine that Jeanne Calment had been given was an anticholinergic drug.

Anticholinergic drugs

Anticholingerics are drugs which block the actions of an important nerve transmitter called acetycholine, a brain chemical that is crucial to memory circuits. You need acetylcholine for good memory. Anticholingeric drugs work by blocking the binding of acetylcholine to its receptor in nerve cells. Anticholingeric drugs cover quite a broad range of medication. They include antihistamines, drugs used in psychiatry such as tricyclic antidepressants like Elavil, drugs used for urinary incontinence, bronchodilators used in the treatment of COPD (chronic obstructive pulmonary disease) like Atrovent and Combivent, antiemetics, antispasmodics, antiarrhythmic drugs like Digoxin, drugs for high blood pressure like Procardia, analgesics like codeine, anti Parkinson drugs, corticosteroids like prednisone, skeletal muscle relaxants, ulcer drugs, diuretics like furosemide (Lasix), anti reflux drugs like ranitidine (Zantac), warfarin, psychotropic drugs, anti-anxiolytics (anti anxiety drugs). Benzodiazepine is an anti-anxiolytic and has a very high anticholinergic load. The benzodiazepine family of depressants is used to produce sedation, induce sleep, relieve anxiety and muscle spasms, and to prevent seizures. Of drugs that affect central nervous system function, benzodiazepines are among the most widely prescribed medications in the United States. Short-acting benzodiazepines are generally used to manage insomnia. These include triazolam (Halcion), zolpidem (Ambien), and zaleplon (Sonata). Benzodiazepines with a longer duration of action are used to treat insomnia in patients with daytime anxiety. These include alprazolam (Xanax) and diazepam (Valium).

A study of mild cognitive impairment and use of anticholinergic drugs

On Feb. 1, 2006, a study was published in the British Medical Journal entitled, "Non-degenerative mild cognitive impairment in elderly people and use of anticholinergic drugs: longitudinal cohort study." The research director was Dr. Karen Ritchie. The objective of the study was to assess the potential of anticholinergic drugs as a cause of non-degenerative mild cognitive impairment in elderly people. The study was undertaken because experimental and clinical studies have consistently shown that dysfunction of the cholinergic system has a detrimental impact on cognitive performance. Drug consumption in elderly people is high, and many commonly prescribed drugs have anticholinergic effects. Furthermore, such drugs are likely to have a more toxic effect in an ageing brain because of increased permeability of the blood brain barrier, slower metabolism and drug elimination, and polypharmacy. In US nursing homes more than 30 percent of elderly residents take more than two anticholinergic drugs, and 5 percent take more than five. An estimated 51 percent of the general population use anticholinergic drugs.

The results of the study: Eighty per cent of the users of anticholinergic drugs were classified as having mild cognitive impairment compared with 35 percent of non-users, and anticholinergic drug use was a strong predictor of mild cognitive impairment. But users were not at increased risk for dementia. No difference was found between users and non-users in risk of developing dementia at follow-up after eight years.

Drugs used to treat Alzheimer's inhibit the enzyme which breaks down acetylcholine. This enzyme is acetyl cholinesterase. The drugs used to break this enzyme down are called acetyl cholinesterase inhibitors. These are pro-cholinergic drugs. In the conclusion of their study, the authors point out that the aim of identifying mild cognitive impairment is the early treatment of dementia, notably with acetyl cholinesterase inhibitors. Therefore, people with mild cognitive impairment due to anticholinergic drugs could be in the absurd situation of receiving pro-cholinergic drugs to counteract the effects of anticholinergic drugs. The authors cautioned doctors and researchers to take into account the possibility that cases of mild cognitive impairment might be due to anticholinergic drug use and that anticholinergic drugs should be considered as a possible reversible cause of mild cognitive impairment.

Mary Lou Williams, M. Ed., is a writer in the field of nutrition. She welcomes inquiries. She can be reached at 267-6480.

 
 

 

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