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Are you thinking straight? Dr Maite Tome, consultant cardiologist at the Heart Hospital in London, explains how cardiomyopathy and sometimes the drugs used to treat it can affect your mental abilities
Cognition refers to the act or process of knowing. It includes every mental process that allows people to acquire knowledge, including reasoning, comprehension, judgement, memory and perception.
Cognitive impairment can be of different degrees, mild or severe; can be transient or permanent; can be reversible or irreversible; and can be stable or progressive.
Cognitive skills can be affected by many external factors but also by internal processes and by our overall health.
An example of an external cause is alcohol abuse; it alters the capacity of judgement, our memory, reasoning and perception.
The impairment is transient and reversible and can be mild or severe. However chronic abuse of alcohol causes progressive cognitive impairment that can be irreversible.
Internal causes, such as depression, can make it difficult for people to concentrate, affecting the ability to learn new things.
Depression can also alter perception and our capacity for judgement and reasoning.
If you have a serious medical condition, other factors can influence your cognitive powers. These are:
♥ Apprehension, anxiety and depression
♥ The disease’s natural history
♥ Side effects of drugs
Elderly people are more sensitive to the side effects of drugs, and special attention is required to assess reversible causes of cognitive impairment.
Heart diseases and cognitive impairment
Some genetic diseases or syndromes affect the heart as well as other organs such as the brain.
Cognitive impairment can be present in the early stages of life, and be serious and permanent. This is the case, for example, in a fifth of people with Leopard syndrome. This condition is also associated with hypertrophic cardiomyopathy. For some people with cardiomyopathy, the disease is caused by another condition.
These other conditions can be associated with multiple organ problems including limb muscle diseases and different degrees of cognitive impairment.
A failing heart is a known cause of cognitive impairment, irrespective of the cause of the heart failure. The brain will be affected by a poor blood supply being pumped from the heart.
Cognitive impairment in chronic heart failure
According to studies, executive function, memory, language and mental speed are most commonly affected by heart problems. How severe your disease is correlates with the degree of cognitive impairment.
Cardiomyopathy and cognitive skills
As described earlier, some genetic syndromes can alter both brain and heart function.
In most adult cardiomyopathies, if cognitive impairment is present, it is most commonly associated with disease progression and heart failure. This is irrespective of the type of cardiomyopathy - hypertrophic, dilated, restrictive or arrhythmogenic right ventricular cardiomyopathy.
Disease complications such as a stroke or cardiac arrest are well known causes of mental impairment. Other factors linked with cardiovascular disease, such as raised cholesterol, diabetes and high blood pressure, can also cause cognitive impairment.
Drug-induced cognitive impairment
Numerous cardiac drugs have the potential to alter mental status.
Acute changes in patients’ mental abilities at the start of a new medication should always be taken into account.
Chronic side effects are, however, more difficult to diagnose and can be confused with some old age behaviour.
If a patient has experienced any medication side effects like confusion, depression or acute delirium in the past, it is important to tell your doctor before any new drugs are prescribed. Acute confusion is a serious health problem and should be listed and treated as previous known allergies to medication.
Drugs can play a part
Anticholinergic drugs, which act by blocking acetylcholine, have the potential to cause delirium and confusion. Heart drugs that have an anticholinergic effect are digoxin, disopyromide, quinidine and procainamide.
This type of blocking action is common in over-the-counter non-cardiac drugs too, such as some antihistamines, antidepressants, antispasmodics for abdominal bloating, and medication for glaucoma.
The side effect of a single medication can be minimal but in combination with other “non offensive” drugs can be enough to trigger an acute episode of confusion.
In drugs to treat high blood pressure, alpha blockers, like clonidine and methyldopa, can sedate and confuse. Reserpine can cause depression. Betablockers can cause the appearance of dementia although this is rare. The most common side effect of betablockers is fatigue or drowsiness.
Antiarrhythmic drugs like digoxin, amiodarone, lidocaine, disopyramide, procainamide, quinidine, flecainide, mexiletine, propafenone, tocainide can also alter cognitive abilities.
Dipyridamole has been shown in some studies to be associated with lower scores in mental tests. Calcium channel blockers, such as verapamil and diltiazem, and ACE inhibitors, such as captopril and enalapril, have a lower risk of inducing cognitive impairment. Often the reaction to some of the drugs above and amiodarone are due to the make-up of that person and so are specific to the individual.
What to do
If you are concerned by changes in your ability to perform tasks, remember things or concentrate when on a new medication, you should talk to your doctor. It is important to collect detailed information about your concerns and also any other medication used at the same time.
Before stopping the medication or attributing new symptoms to a new drug, it is important to let your doctor know. For example, stopping blood pressure medication suddenly can lead to an acute brain injury and major permanent cognitive impairment.
Some of the medication side effects can be overcome by increasing the dosage of the new drug, for example beta blockers, very slowly.
♥ It is also important to remember that cardiac drugs, especially when used in the highest recommended doses, improve the quality of life of cardiomyopathy patients and the performance of many organs, including the brain.