Which type of dementia progresses fastest?

What are rapidly progressive dementias?

Rapidly progressive dementias (RPDs) are neurological disorders that typically involve a fast cognitive decline over weeks, months, and in some cases days. ^[3]

Many dementias are characterized by mild symptoms which gradually worsen. However, RPDs can quickly be fatal. For example, CJD usually leads to death within 1 year of inception. ^[2]

What conditions cause RPDs?

RPDs can be stimulated by a variety of conditions. The following mnemonic illustrates types of condition that bring on RPDs (VITAMINS). ^[3]

• Vascular – obstructed blood flow to brain, such as strokes, can cause sudden vascular dementia
• Infectious – secondary, insidious, neurodegenerative effects from a viral infection e.g. HIV
• Toxic-metabolic – vitamin deficiencies/excesses, nutritional disorders or side effects of prolonged drug abuse
• Autoimmune – complications of autoimmune diseases causing the body to attack brain tissue
• Metastases – cancer from malignant tumors causing RPDs
• Iatrogenic – RPDs brought on by medical examination or treatment – e.g. medications or unsanitary equipment/facilities leading to conditions which lead to dementia
• Neurodegenerative – any other neurogenerative complication that presents itself alongside dementias e.g. CJD
  
• Systemic or seizures – seizures diseases that affect the whole body that can contribute to brain malfunction

How are RPDs diagnosed?

Accurately diagnosing RPDs as early as possible is essential to ensuring patients suffer as little brain damage as possible. However, RPDs can prove difficult to diagnose.

Tests are usually carried out in a controlled, hospital setting to identify whether other common causes of cognitive decline are affecting a patient. These include infections, toxic or metabolic afflictions, and autoimmune diseases. ^[1]

Many instances of sudden cognitive decline may be explained by these underlying medical conditions. Once the underlying conditions are treated, the symptoms usually abate.

If no underlying causes are found, patients undergo CT scans, MRI scans and EEGs. The results of these are typically combined with a rigorous questionnaire assessing the patient’s medical history. A doctor will then use the information garnered from these efforts to confirm a diagnosis of an RPD.

What happens in RPDs?

RPDs affect each person differently and are usually affected by an underlying cause. Typically, people with RPDs develop cognitive problems, behavioral and mood problems, coordination issues, and speech issues.

While the progression of some RPDs, like CJD, cannot be stopped, there are many that can be treated and potentially reversed if caught at an early stage. ^[2]