Understanding The Different Types Of Alzheimer's And Dementia

People often use the term “Alzheimer’s disease” to describe all forms of aging-related cognitive decline. However, there are at least two different types of Alzheimer’s disease—not to mention many other kinds of dementia. These diseases share some key features but typically differ in their causes, symptoms, and progression patterns. Understanding the different types of Alzheimer’s and the other forms dementia can take can be helpful for recognizing warning potential signs or understanding the evolving needs of a loved one with one of these conditions.

Dementia can refer to many different forms of ongoing decline in mental skills, such as memory, attention, speech, and impulse control. Alzheimer’s disease is the most common form, but others include vascular dementia, dementia with Lewy bodies, Creutzfeld-Jakob disease, and more. Additionally, Alzheimer’s disease can be further divided into two types, distinguished by their risk factors and onset time. Read on for a closer look at all of the above.

Alzheimer’s disease: The most common type of dementia

Scientists have identified several different types of dementia, but Alzheimer’s disease (AD) is the most well-known and the most prevalent. The World Health Organization estimates that this condition may be at least partially responsible for 60–70% of dementia cases worldwide. 

People with Alzheimer’s disease develop unhealthy deposits of protein fragments, known as amyloid plaques, in the gray matter of their brains. The buildup of these plaques typically disrupts and destroys healthy brain cells.  

This disease is commonly broken down into two types:

1. Younger-onset or early-onset Alzheimer’s disease. According to the Alzheimer’s Association, this typically includes cases in older adults who are under age 65, though some may be affected as early as their 30s or 40s.
2. Late-onset Alzheimer’s disease. This is by far the most common type of Alzheimer’s. Researchers estimate that roughly 95% of people with AD develop symptoms at age 65 or older.

Some experts view the “cutoff age” of 65 as largely arbitrary, based more on the typical retirement age than on a noticeable difference in disease progression. A more relevant distinction may be whether the disease is inherited or not. A small number of AD cases seem to be passed down along family lines—which is known as familial Alzheimer’s disease, as opposed to non-familial or sporadic Alzheimer’s disease.

The Alzheimer’s Association also suggests watching out for symptoms like:

• Confusion about location and time, such as forgetting the date or season or not recognizing a familiar place
• Challenges with daily tasks like driving, shopping, or organizing the home
• Mood and personality changes, often including symptoms of depression, fearfulness, anxiety, suspicion, and/or irritability
• Social withdrawal and self-isolation
• Challenges with planning and problem-solving
• Trouble following a conversation
• Forgetting familiar words often

As this degenerative, currently incurable disease worsens, these symptoms typically get more severe, eventually reaching a point where a person with AD will be unable to manage simple tasks independently. They may rarely know where they are and be only sporadically able to recognize close friends and relatives. Affected individuals can often seem to withdraw into themselves, losing awareness of what’s happening around them.

Other types of dementia

Though Alzheimer’s disease is currently the most prevalent form of dementia, there are many others, including the following.

Vascular dementia

This type of dementia is caused by brain damage due to blood supply disruptions. Researchers consider it to be the second most common kind of dementia, and it’s believed to play a role in 20% or more of all instances of dementia. It can be caused by a variety of diseases that affect the blood vessels in the brain. 

Unlike with AD, vascular dementia symptoms tend to appear suddenly—often after a stroke or a series of small strokes. It’s also not always progressive and affected individuals may even recover some cognitive function. However, if an underlying disease causes repeated strokes, brain damage may accumulate over time, causing ongoing decline and even death.

Symptoms may resemble those of AD, and the two diseases can occur together. However, the earliest signs of vascular dementia typically include challenges with orientation in space and time rather than memory loss. 

Frontotemporal dementia (FTD)

FTD is believed to be the most common early-appearing type of dementia, usually developing between the ages of 40 and 65. FTD can be caused by several different types of neurodegenerative diseases that typically most strongly affect the frontal and temporal lobes of the brain. The primary symptoms of frontotemporal dementia usually include personality changes and loss of language abilities and behavior control.

FTD can be further classified into subtypes. For example, behavioral variant frontotemporal dementia (BVFTD) tends to involve changes like:

• Apathy and lack of motivation
• Impulsiveness 
• Trouble controlling cravings (e.g., compulsive shopping or overeating)
• Decreased empathy
• Inappropriate and vulgar speech or actions

In contrast, primary progressive aphasia (PPA) may primarily involve challenges with language. It can be divided into three further subtypes:

1. Semantic dementia (SD). People with this condition may find it challenging to understand the meanings of words.
2. Progressive non fluent aphasia (PNFA). This variant typically manifests as increasing challenges in forming speech, including stuttering, frequent pauses, and disrupted grammar.
3. Logopenic aphasia (LPA). Those with this form of dementia may understand the meanings of words but can have challenges retrieving them in conversation.

Dementia with Lewy bodies (DLB)

Like Alzheimer’s disease, DLB seems to be caused by non-functional clumps of proteins forming in the brain. However, unlike the plaques seen in AD, Lewy bodies typically appear inside brain cells and disrupt their internal structure.

This kind of dementia often begins around age 50. Early symptoms may be mild and can include feelings of dizziness and symptoms of anxiety and depression. As the disease progresses, cognitive symptoms resembling AD can appear, such as challenges related to planning, reasoning, and memory.

DLB also typically manifests as vivid, repeated visual hallucinations involving perceptions of familiar people or strange creatures. Those with this condition may also experience a variety of sleep disturbances, such as daytime sleepiness or trouble sleeping at night. One common sleep-related symptom in particular is REM sleep behavior disorder, in which patients act out their dreams while unconscious—often violently.

Huntington’s disease (HD)

Huntington’s disease is a condition that can cause dementia. Unlike the other diseases mentioned here, it appears to have a clear genetic cause: a mutation of the HTT gene, which codes for an important molecule in nerve cells. Mutated versions of this protein are typically unstable and break down quickly, potentially resulting in the progressive destruction of nervous system cells. In most cases, this disease is inherited from a parent.

Some symptoms of Huntington’s disease can be similar to those of Alzheimer’s, though it may also manifest as disruptions to motor function such as trouble swallowing and jerky, uncontrollable muscle movements. The average age of HD onset is typically earlier than with AD—usually between ages 30 and 50. There is also an early-onset type of HD which can begin in childhood and often includes Parkinson’s-like symptoms. Currently, there is no known cure or treatment for Huntington’s disease.

Creutzfeldt-Jakob disease (CJD)

This rare condition is caused by an incorrectly folded protein called a prion. Healthy proteins that come into contact with prions may alter their shapes and become prions as well. This can then cause the deformed molecules to spread rapidly through the brain, causing dementia and, subsequently, death. 

The symptoms of CJD can manifest differently depending on which parts of the brain are affected first, but they often include:

• Depression
• Paranoia
• Memory loss
• Jerky movements
• Loss of balance
• Hallucinations
• Paralysis

There is no known cure for Creutzfeldt-Jakob disease, and the symptoms can increase in severity quickly. Most people with this disease typically die within six months of diagnosis, though some may live for up to two years.

Reducing your risk of dementia

Some causes of dementia, such as inheriting the genes that can cause Huntington’s disease, are not currently within human control. However, there are several known risk factors for dementia that you may be able to moderate with healthy lifestyle choices. For example, regular physical exercise appears to lower the risk of Alzheimer’s disease. It may also help you avoid heart disease and diabetes, both of which can increase your likelihood of developing vascular dementia. Quitting smoking and reducing your alcohol intake can also help.

High blood pressure is another well-known risk factor for several types of dementia. Monitoring this vital sign and working with your doctor to keep it within healthy limits can help you maintain a healthy brain as you age. Studies suggest that engagement in intellectual and social activities may also improve cognitive health and lower one’s odds of developing dementia. 

Therapy for coping with dementia symptoms in yourself or a loved one

Whether you’re experiencing early dementia symptoms or caring for a loved one with an illness in this category, any of the conditions described above can take a serious emotional toll. Getting help from a therapist may make it easier to manage stress and avoid or reduce symptoms of fatigue, depression, anxiety, and/or burnout. Online therapy can be a convenient option for those experiencing cognitive symptoms or who act as caregivers for someone else and can’t easily commute to in-person sessions.

There’s a growing body of research that indicates the potential effectiveness of online therapy options. For example, a 2020 study suggests that internet-based cognitive behavioral therapy can help address symptoms of anxiety and depression in adults. Regardless of the format you may choose, the support of a therapist could represent a valuable source of support as you navigate this challenging period of life.