Rapidly progressive dementias (RPDs) are dementias that progress quickly, typically over the course of weeks to months, but sometimes up to two to three years. RPDs are rare and often difficult to diagnose. Early and accurate diagnosis is very important because many causes of RPDs can be treated.
What Causes RPD?
Many conditions can cause RPD. Some possible causes include:
- Autoimmune diseases (conditions that over-activate the immune system)
- Unusual presentations of more common neurodegenerative diseases (such as Alzheimer’s disease)
- Prion diseases (rare forms of neurodegenerative disease)
- Infections
- Impaired blood flow to or in the brain
- Exposure to toxic substances
- Vitamin deficiencies
- Cancer
- Toxicity from prescribed medications
- Recurrent seizures
What Happens in RPD?
The progression of RPD varies from patient to patient and in part depends on the underlying cause. Patients typically develop problems with their thinking, mood/personality/behavior, ability to speak or understand, or ability to control their movements. Many are often treatable and reversible if diagnosed quickly. For some other RPDs, there are no cures, and the progression of symptoms is inevitable. There may be some treatment to help relieve specific symptoms. Patients with non-curable forms of RPD may die within months or a few years from onset.
How is an RPD Diagnosed?
RPD can be difficult to diagnose, so it is often necessary to see a doctor who specializes in these conditions. The doctor might ask about the patient’s progression of symptoms, any similar illnesses in biological relatives or any recent possible exposures (i.e., toxins, travel history). The doctor may request some laboratory testing, such as blood, urine, and cerebrospinal fluid (the clear liquid that surrounds the brain and spinal cord); brain imaging (such as an MRI) and/or an electroencephalogram (a non-invasive test that measures brain electrical activity from the scalp). The information gathered by the physician and tests might help to determine the cause of disease.
How are RPDs Treated?
Treatment depends on the type of RPD that was diagnosed. For example, if the RPD is the result of cancer or a hormone imbalance, treatments that target these specific conditions may help treat the RPD. Unfortunately, for many causes of RPD, there is no cure available. For these cases, however, we can sometimes treat the symptoms, make patients more comfortable and improve their quality of life.
