9 Forms of Dementia (That Aren’t Alzheimer’s)

Learn about other related brain disorders that interfere with cognitive function.

Medically reviewed in January 2021

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When you hear the word dementia, what immediately springs to mind? It’s probably Alzheimer’s disease. Alzheimer’s is the sixth-leading cause of death in the United States and one of the best-known and scariest conditions for people as they age. But it’s not the only form of dementia.

Dementia is an umbrella term for a number of conditions that cause problems with thinking, judgment or memory. Alzheimer’s accounts for between 60 to 80 percent of all cases of dementia, but other brain disorders can cause it as well. Here are some of the other conditions that cause dementia.

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Vascular dementia

High blood pressure isn't just a risk factor for heart disease. It can also lead to dementia, among other problems. Vascular dementia is typically caused by a series of small strokes, when areas of the brain are deprived of oxygen and brain cells die. High blood pressure, smoking, diabetes, atherosclerosis and a previous history of strokes are the most common risk factors.

Vascular dementia is second only to Alzheimer’s as the most common form of dementia in people over age 65. Symptoms can vary widely, depending on the part of the brain affected, and symptoms may progress in noticeable steps, with periods of stability or even occasional improvement.

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Parkinson’s disease dementia

Most people associate Parkinson’s disease with speech problems and tremors. Those are the most common symptoms, since Parkinson’s destroys the brain’s ability to make a chemical—dopamine—that’s important for movement.

But Parkinson’s can also cause dementia-like symptoms, including trouble remembering recent events, difficulty making decisions and problems judging distance. Between 50 and 80 percent of people with Parkinson’s eventually have these symptoms. Dementia most often doesn’t develop until 10 to 15 years after a Parkinson’s diagnosis.

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Dementia with Lewy bodies

Dementia with Lewy bodies (DLB) has similar symptoms to Alzheimer’s and is related to Parkinson’s. It’s the third most common type of dementia after Alzheimer’s and vascular dementia. DLB is the result of abnormal protein deposits in the brain, known as Lewy bodies, which cause brain cells to work less effectively and to eventually die.

Some researchers think that Parkinson’s and DLB are actually the same disease, just expressed differently. Lewy bodies are seen in both conditions. Motor symptoms show up first in Parkinson’s, but dementia symptoms show up first with DLB.

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Frontotemporal dementia

Just as dementia is an umbrella term for cognitive problems, frontotemporal dementia is an umbrella term for diseases that cause shrinking in the areas of the brain called the frontal and temporal lobes, which help govern personality, behavior and language.

Frontotemporal dementia often occurs earlier than Alzheimer’s; it usually strikes when people are between 40 and 45 years old. The causes of frontotemporal dementia are usually unknown. While some gene mutations can cause it, more than half of the people who develop the condition have no family history of dementia.

Frontotemporal dementia can trigger extreme behavior changes, including:

  • Inappropriate behavior like theft or promiscuity
  • Loss of empathy
  • Decline in hygiene
  • Apathy
  • Poor judgment
  • Trying to eat inedible objects
  • Speech and language problems

Parkinson’s-like movements may develop as well. 

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Korsakoff syndrome

Korsakoff syndrome is a decline in memory that’s caused by a vitamin B1 deficiency. Because B1 deficiency is common in long-term alcoholics, Korsakoff syndrome is sometimes known as “wet brain.” Korsakoff syndrome can cause severe memory loss and prevent people from forming new memories. Hallucinations sometimes occur as well.

It often occurs alongside a condition called Wernicke encephalopathy, which can create confusion, memory and learning problems. The two diseases are often spoken of together, as Wernicke-Korsakoff syndrome. A vitamin B1 shot can help with some of the symptoms of Wernicke encephalopathy.

Recovery from the condition varies: About a quarter of those with Korsakoff syndrome recover, but it may take a year or more and requires abstaining from alcohol. About half show some improvement in cognitive function, while the remaining 25 percent are unchanged.

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Chronic traumatic encephalopathy

Chronic traumatic encephalopathy (CTE) is another brain condition that causes dementia symptoms. People get CTE from repeated blows to the head. Not surprisingly, athletes in high-contact sports like boxing and football are especially prone to it. CTE may result in:

  • Cognitive impairment
  • Impulsivity
  • Depression
  • Memory loss
  • Difficulty planning
  • Aggression
  • Suicidal thoughts
  • Speech difficulties
  • Movement problems and difficulty swallowing

CTE diagnosis can only be definitively diagnosed after the patient has died, with an autopsy. 

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Less common forms of dementia

Other more rare forms of dementia include:

  • Huntington’s disease. This is a fatal condition caused by a defective gene. Along with dementia symptoms like impulsivity and difficulty focusing, it can cause movement and muscle problems and depression. Symptoms usually develop in a person’s 30s or 40s. When it develops earlier than age 20, it’s known as juvenile Huntington’s disease and often progresses more quickly.
  • Creutzfeldt-Jakob disease. This is another fatal brain disease that has no cure. It is a prion disease, related to mad cow disease and kuru. When prion proteins in the brain begin to fold into abnormal shapes, they destroy brain cells. It leads to personality changes, memory problems and impaired vision that can progress to blindness. The most common subtype usually begins around age 60.
  • Normal pressure hydrocephalus. This occurs when cerebrospinal fluid backs up into the brain’s hollow spaces. Cognitive impairment, urinary incontinence and difficulty walking are symptoms. The cause of normal pressure hydrocephalus is unknown in most cases, although hemorrhages, tumors, head trauma and infections can lead to the condition. A shunt may be used to drain the excess fluid, which sometimes helps people walk better, but the dementia symptoms and incontinence are more difficult to treat. 

This slideshow was updated on August 31, 2018.

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