13 Kinds of Diseases that Cause Dementia - Symptoms and Prognosis


Alzheimer's Disease


Dementia is an umbrella term that covers many types of cognitive impairment. Symptoms of dementia generally include memory loss, poor judgment, communication difficulties, and personality changes.

Often, early symptoms are especially helpful in distinguishing the different types of dementia from each other.

The most common cause of dementia is Alzheimer's disease.

Initial Symptoms: Early symptoms include short-term memory loss, poor judgment, and difficulty finding the right words.

Progression: Alzheimer's usually progresses from the early stages to the middle stages in 2-4 years. In the middle stages, cognition continues to decline and behavioral and psychological symptoms of dementia sometimes develop, making it a particularly challenging for the person with dementia and his caregiver.

Prognosis: Average life expectancy is Alzheimer's disease ranges from 8 to 10 years after diagnosis, although some people live up to 20 years.


Vascular Dementia

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Early Symptoms: Initial symptoms often include word-finding difficulty, memory loss, challenges in executive functioning and slow processing speed. These symptoms may be related to a transient ischemic event, a stroke or unnoticed small vessel disease (which includes changes in the brain such as white matter lesions and narrowing of the arteries).

Progression:  Vascular dementia typically has a step-like progression, as opposed to a gradual decline more typical of Alzheimer's. This means that functioning in vascular dementia may remain stable for quite some time after the initial symptoms until a noticeable decline occurs, and then remain at that next level for an extended period again until the next decline develops.

Prognosis: Prognosis in vascular dementia varies greatly and is related to how much damage there is in the brain and other occurrences of strokes or TIAs.


Parkinson's Disease Dementia

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Initial Symptoms: Parkinson's disease dementia is one type of Lewy body dementia. (The other is called dementia with Lewy bodies.) Both involve body changes (such as slow movements, weakness, and rigidity) and brain changes (such as memory loss, a decrease in attention and poor executive functioning.)

In Parkinson's disease dementia, the motor and mobility symptoms are present for at least one year before the cognitive changes develop.

Progression: Parkinson's disease dementia usually has a gradual progression over time. Hallucinations often become common and confusion is likely to increase. Falls may also become more frequent and overall physical functioning declines.

Prognosis: Average life expectancy varies significantly depending on the health of the person and the age at which Parkinson's developed.


Dementia with Lewy Bodies

Lewy Body Dementia
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Initial Symptoms: Dementia with Lewy bodies is a type of Lewy body dementia. (The other kind is Parkinson's disease dementia.) Dementia with Lewy bodies involves both body symptoms such as motor and muscle weakness and rigidity, as well as brain symptoms like making decisions, memory impairment, and attention span.

In dementia with Lewy bodies, the brain symptoms develop before the body symptoms, at the same time or less than a year after the body symptoms present.

Progression: Dementia with Lewy bodies can vary quite a bit, even from day to day.

Prognosis: Average life expectancy depends on many factors but is estimated to be approximately 8 years after diagnosis.


Wernicke-Korsakoff Syndrome

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Initial Symptoms: Wernicke encephalopathy is an acute condition characterized by confusion, changes in vision and eye functioning, decreased mental alertness, leg tremors and more. It often, but not always, is related to alcohol abuse and requires immediate treatment in a hospital, typically of thiamine administration.

Korsakoff syndrome is more of a chronic condition consisting of impaired memory, confabulation (making up stories) and hallucinations.

Progression: If treated right away, it's possible that Wernicke encephalopathy can be reversed. However, it sometimes is followed by the ongoing symptoms of Korsakoff syndrome.

Prognosis: Average life expectancy in Wernicke-Korsakoff syndrome varies significantly. It ranges from essentially no effect in someone who abstains from alcohol to a dramatically shortened expectancy in others.


Creutzfeldt-Jakob Disease (sometimes called Mad Cow Disease)

Image of Brain Tissue Affected by Cruetzfeldt-Jakob Disease. CDC/Teresa Hammett

Initial Symptoms: Unlike other types of dementia, the first symptoms of Creutzfeldt-Jakob disease don't typically include cognitive changes. Rather, they include depression, withdrawal, and mood changes.  

Progression: As the disease progresses, memory difficulties develop, along with changes in behavior, physical coordination including walking, and vision. In the later stages, hallucinations and psychosis may develop, and overall functioning, including the ability to swallow and eat, deteriorate.

Prognosis: Average life expectancy is significantly affected and ranges from a few weeks to a year after diagnosis. 


Frontotemporal Dementia (Pick's Disease)

Pink = Frontal Lobe. Yellow = Temporal Lobe. Stocktrek Images Stocktrek Images/Getty Images

Initial Symptoms: Frontotemporal dementia is a type of dementia that more commonly affects younger people. Early symptoms usually include changes in personality and behavior, as opposed to cognitive difficulties. They may appear not to care about others and act inappropriately.

Progression:  As FTD progresses, communication (both the ability to express and understand), memory, and physical ability decline.

Prognosis:  Depending on what type of FTD the person has developed, life expectancy ranges from approximately two to twenty years after diagnosis.


Huntington's Disease (Huntington's Chorea)

Huntington's disease is passed on genetically through DNA, pictured here. Laguna Design Photolibrary/Getty Images

Initial Symptoms: Huntington's disease initially involves a combination of symptoms including involuntary physical movements, mood changes, memory loss and poor decision-making skills.

Progression: As it progresses, Huntington's affects communication, walking, swallowing and cognition. Involuntary movements (chorea) become more pronounced and interfere significantly with daily functioning.

Prognosis: Life expectancy in Huntington's ranges from 10 to 20 years after diagnosis.


HIV/AIDS Dementia

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Initial Symptoms: People with HIV-related dementia initially often have difficulty with concentration, attention, and memory. They may also show some changes in their personality and behavior.

Progression:  As HIV-associated dementia progresses, physical abilities may also begin to decline. For example, someone may have more difficulty with walking or hand-eye coordination.

Prognosis:  Prognosis varies and may depend on the body's response to treatments such as highly active anti-retroviral therapy (HAART).


Fatal Familial Insomnia

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Initial Symptoms: Sleep is significantly affected by this rare hereditary condition. A person may experience insomnia, vivid dreams, and hallucinations, as well as anorexia.

Progression: As this condition progresses, the ability to walk and move the body deteriorates. Memory loss and poor attention and concentration develop, and in its late stages, a person often is unable to speak.

Prognosis: After FFI develops, life expectancy is approximately 12 months.


Mixed Dementia

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Initial Symptoms: Symptoms of mixed dementia often appear similar to those of early Alzheimer's disease and include difficulty learning new information, memory loss (typically short-term memory impairment), confusion as to the day or time and word-finding difficulties.

Mixed dementia is often misdiagnosed as a single type of dementia and then discovered either through imaging such as MRIs or in an autopsy after death.

Mixed dementia is often caused by the combination of Alzheimer's, vascular dementia and/or Lewy body dementia.

Progression: As mixed dementia progresses, brain functioning declines further, causing difficulty in physical abilities such as activities of daily living as well, as all areas of cognition.

Prognosis: Life expectancy after diagnosis of mixed dementia is not clearly established because diagnosis is sporadic. However, researchers estimate that prognosis may be shorter for mixed dementia than for a single cause of dementia such as Alzheimer's since additional factors are affecting brain functioning.


Chronic Traumatic Encephalopathy/Brain Injury

Young African man in football uniform laying on field
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Initial Symptoms: Symptoms of brain injury include loss of consciousness, memory loss, personality and behavior changes, and slow, slurred speech.

Progression: While symptoms from a single concussion are often temporary and resolve with appropriate treatment, chronic traumatic encephalopathy typically develops over time from repeated head injuries and is generally not reversible. Later symptoms include poor decision-making ability, aggression, impaired motor function and inability to communicate effectively.

Prognosis: Life expectancy varies according to the severity of injuries.


Normal Pressure Hydrocephalus

Normal Pressure Hydrocephalus (NPH). LAGUNA DESIGN Science Photo Library/ Getty Images

Initial Symptoms: Normal pressure hydrocephalus is characterized by what's commonly caused the triad of symptoms: cognitive decline, difficulty with walking and problems with urinary incontinence.

Progression: Progression varied depending on treatment. NPH is a condition that causes symptoms of dementia but can sometimes be reversed with prompt treatment.

Prognosis: If NPH responds to treatment, walking is often the first symptom that improves followed by continence and then cognition.

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