Looking Into Systemic Conditions that Mimic Alzheimer's Disease - dummies

Looking Into Systemic Conditions that Mimic Alzheimer’s Disease

By Patricia B. Smith, Mary M. Kenan, Mark Edwin Kunik, Leeza Gibbons

A number of other conditions can mimic the symptoms of Alzheimer’s disease, including an underactive thyroid, vitamin deficiencies, too much calcium in the blood, and syphilis that’s spread to the brain. Dementia can also be induced by abusing drugs or alcohol or show up as a symptom of severe clinical depression, traumatic injury, or schizophrenia.

Hypothyroidism or underactive thyroid

No matter what the cause, a person whose thyroid gland is underactive can experience symptoms similar to those of Alzheimer’s disease, including memory loss, irritability, and depression. However, hypothyroidism only accounts for a small number of dementia cases. The key to an accurate diagnosis is the presence of other symptoms common to hypothyroidism but not necessarily present in Alzheimer’s disease, including weight gain; coarse, dry hair; hair loss; dry, rough skin; and constipation. Generally speaking, hypothyroidism can be detected with a simple blood test, although certain cases may require more extensive testing to ensure accurate results.

The condition is readily managed with thyroid medication, but it will require lifelong monitoring to make sure that the dose of thyroid is adequate. After the condition is under control, the memory loss and other cognitive symptoms have a good chance of improving.

Vitamin deficiencies

Some vitamin and nutritional deficiencies can also produce symptoms similar to Alzheimer’s Disease. If someone has a severe lack of certain B vitamins, folic acid, or niacin, that person is at risk for having his or her condition misdiagnosed unless the doctor knows to check for these deficiencies.

Although it’s rare, severe B-1, B-6, and B-12 deficiencies can lead to dementia. Simple blood tests can establish definitively whether a deficiency is present. That’s just one reason why the blood tests your physician orders at the beginning of the diagnostic process are so important; they can rule out more easily treated causes of dementia such as vitamin deficiency.

Niacin deficiency is another nutritionally based condition that can produce dementia, memory loss, and irritability. However, a niacin deficiency severe enough to cause dementia will actually induce a disease called pellagra, which causes diarrhea and dermatitis at the same time as the dementia. Diagnosis is made through a physical exam and symptoms. Niacin deficiency is generally rare in people who consume healthy diets, but is more common among alcoholics who may have poor dietary habits.

Folic acid deficiency is one of the most common nutritional deficiencies in the United States. It’s particularly prevalent in people who abuse alcohol. It can cause irritability and difficulty in concentrating. However, people who suffer from a folic acid deficiency also have elevated levels of serum homocysteine (a chemical byproduct of protein metabolism found in the blood), which is something that Alzheimer’s patients don’t necessarily have. Blood tests can help establish the correct diagnosis.

Doctors not only have to diagnose the deficiency, but they must also figure out what’s causing it. Deficiencies can be caused by inadequate intake, malabsorption, excessive excretion, or an underlying disease. In some cases, the doctor will have to treat the underlying condition as well as supplement the missing nutrient in order to correct the problem permanently.


Hypercalcemia is an electrolyte imbalance caused by too much calcium in the blood. Elevated levels of serum calcium are generally associated with a tumor or primary hyperparathyroidism, a condition that occurs when the parathyroid glands secrete too much hormone. When the level of calcium in the bloodstream gets too high, it may produce an altered mental status and memory problems that are similar to Alzheimer’s disease. A blood test that measures the levels of both calcium and parathyroid hormone can identify the condition. Surgery to remove the parathyroid glands cures hypercalcemia associated with hyperparathyroidism; when the hypercalcemia is associated with a tumor, particularly a malignant tumor, the outlook is less optimistic.

After the parathyroid glands are removed and calcium levels fall back to normal, the accompanying Alzheimer’s-like symptoms diminish. In some cases, the patient may have to take calcium-lowering drugs to help manage the condition.


Syphilis can cause dementia if it spreads to the brain. Although syphilis can readily be cured with antibiotics if it’s diagnosed and treated early on, in patients who don’t seek treatment, the infection can spread to the brain — although it generally takes at least a decade to do so. This infection can produce mental confusion, difficulty in walking, and dementia that mimics Alzheimer’s Disease. If a blood test detects the presence of syphilis antibodies in the blood, the diagnosis can be confirmed with an analysis of spinal fluid.

Syphilis can be cured with a course of antibiotics; however, if the condition has been allowed to go unchecked for a long period of time, the outlook may not be as positive.


Severe clinical depression may be mistaken for Alzheimer’s Disease. People who are severely depressed can experience problems in thinking or memory, including difficulty concentrating, recalling information, and keeping track of dates or time, or they may complain that they can’t stay focused on a task. They may report difficulty making decisions or starting or completing projects, and they may appear apathetic.

A person can have both depression and Alzheimer’s Disease at the same time. A good medical and neuropsychological evaluation is needed to determine if your loved one is experiencing one or possibly both of these conditions. If your loved one is suffering from depression and not Alzheimer’s, you can expect your loved one’s cognitive problems to respond to proper treatment for depression. If your loved one is treated for depression and shows an improved mood but no improvement in thinking or memory, a diagnosis of dementia (possibly AD) may be appropriate. The bottom line is that your healthcare practitioner must assess whether your loved one is depressed before a diagnosis of Alzheimer’s can be made.


Another condition that can cause dementia-like symptoms is delirium. Delirium is suspected when someone shows a fluctuating change in thinking — particularly problems focusing, maintaining, or shifting attention — that usually starts within hours or days. Speech may be incoherent, and the individual may have problems staying awake or become agitated and restless. Disorientation to person, place, or time; mood shifts; or hallucinations may also come and go.

Delirium is the direct consequence of a medical condition often caused by an illness (for example, a urinary tract infection, congestive heart failure, and so on), a metabolic disorder (dehydration, kidney problems), physical trauma (head injury), or cardiac problems. Many drugs commonly used by older adults to treat pain, infection, inflammatory diseases, gastrointestinal problems, and more can also cause delirium. Delirium is a reversible condition if properly diagnosed and treated.

Dementia or delirium can also result from alcohol or drug abuse, so you need to let your healthcare practitioner know if your loved one has a history of drug or alcohol problems, including abuse of over-the-counter medications.

As with depression, a person can have both delirium and Alzheimer’s disease. People who become delirious don’t necessarily have AD, but people with Alzheimer’s are more susceptible to delirium than those without it.


Dementia can also result from certain viral or bacterial infections, such as encephalitis, meningitis, or HIV, but doctors rarely confuse these acute conditions with AD, even if some of the symptoms are similar.


Poisoning can be another cause of dementia. A wide variety of poisons can produce dementia, including organophosphates that are used in agriculture and chronic exposure to low levels of carbon monoxide. Heavy metals such as lead and mercury have well-documented neuro-toxic effects and have also been demonstrated to produce dementia.

Because of the number of possible causes for dementia, your doctor will want to take a thorough medical history, including what drugs your loved one is taking and the start/stop dates for those drugs. Because so many different conditions can produce symptoms typically associated with Alzheimer’s disease, you doctor must rule out all other potential causes and ensure that your loved one’s symptoms fit the criteria for Alzheimer’s before he or she arrives at a diagnosis.