Reversible Cognitive Disorder – Medical Conditions

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Common reversible conditions that can cause cognitive impairment include thyroid problems, dehydration, malnutrition, infections, or problems with medications.

The thyroid is a gland that secretes hormones (chemical messengers) that control how quickly the body burns energy, makes proteins, and how sensitive the body is to other hormones. Hypothyroidism (an underactive thyroid that does not secrete enough hormones) and hyperthyroidism (an overactive thyroid that produces an excess of hormones) can cause cognitive problems such as forgetfulness and difficulty concentrating. These diseases typically affect women (most often those who are menopausal), people with a family history of thyroid disease, people over 60 years of age, smokers, and people who have been exposed to radiation. Thyroid problems are treated with medications that either raise low hormone levels or suppress an overactive thyroid. Some people with thyroid problems notice that their cognitive symptoms improve within a few days or weeks after starting medication treatment.


Dehydration occurs when the body has lost too much water, which affects the transportation of nutrients and oxygen to tissues and the ability to maintain appropriate electrolyte levels (chemicals that are critical for nerve and muscle function such as sodium and potassium). Dehydration occurs more often among children, people with chronic illnesses, and older adults. Severe dehydration can cause confusion which resembles dementia, and in severe cases, death. Dehydration is treated by replacing fluids and electrolytes with water or liquids that contain electrolytes, such as some sports drinks. In severe cases, fluids may need to be given intravenously (administered directly into a vein). The length of time it takes for symptoms to resolve depends on the severity of the situation.

Malnutrition occurs when people are not getting enough nutrients due to an inadequate (not enough food) or unbalanced (too few healthy foods) diet, or digestive problems that interfere with nutrient absorption. Long-term malnutrition can cause starvation, disease, and infection. Malnutrition is more common among people who are poor and/or who are chronically ill. Vitamin B12 deficiency is one of the most common types of malnutrition, and confusion is the most common cognitive effect. Malnutrition is treated by replenishing the body with the nutrients it is lacking either through dietary changes, or in severe cases, intravenously (administered directly into the vein). The length of time it takes for symptoms to resolve depends on the severity of the malnutrition and whether there is an underlying medical condition causing the problem.

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Infections can cause cognitive problems by affecting the brain's ability to function correctly. Common cognitive symptoms caused by infections include confusion, difficulty concentrating, or forgetfulness. Urinary tract infections are a common cause of cognitive problems among older adults. Infections are treated with antibiotics, and symptoms often subside quickly after starting treatment.

Medication problems include taking the wrong dosage of a medication (e.g., the dose is too high), taking the wrong medication altogether, or medication interactions (when two or more drugs react with each other and cause negative side effects). The most common medications that cause cognitive disorders are sedatives (used for reducing anxiety or improving sleep), hypnotics (used for improving sleep), blood pressure medications, and arthritis medications. Medication problems occur more frequently in older adults because their bodies do not break down and absorb medications as quickly as younger people. Cognitive symptoms caused by medication problems reverse as soon as the problem is corrected.

Uncovering a reversible medical cause for a cognitive disorder involves a full diagnostic workup, similar to the diagnostic procedures described for the dementias (click here to return to that discussion). Pinpointing the cause of the cognitive symptoms can be an intricate process due to a person's complex history. Exploring several different potential explanations of symptoms might be necessary before arriving at an accurate diagnosis. Again, with proper treatment of these conditions, a person's cognitive symptoms should go away.

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