While Alzheimer’s is the most common form of dementia, there are many other types as well. In this section, we explain the causes and main signs of some of the different types of dementia.
Vascular dementia is the second most common type of dementia, accounting for roughly 15-20% of dementia cases in Europe. Vascular dementia is caused by impaired blood flow to the brain, which results in damage to the brain cells and leads to problems with memory, reasoning, planning and other thought processes.
Diseases that damage blood vessels and reduce circulation can cause vascular dementia. Stroke, which occurs when blood flow to the brain is interrupted by a blood clot or bleeding, is one of the most common causes of vascular dementia. Vascular dementia can also arise when our blood vessels are badly damaged or narrowed by cardiovascular disease, hypertension or type 2 diabetes.
Symptoms of vascular dementia
The symptoms of vascular dementia vary depending on the area of the brain affected by reduced blood flow, and the extent of damage that is caused. Symptoms can start suddenly, for example after a major stroke, or develop gradually over time. Similar to Alzheimer’s dementia, vascular dementia generally gets worse over time, although the rate of progression can vary from person to person.
Unlike Alzheimer’s dementia, however, memory loss isn’t the typical first sign of vascular dementia. Instead, people with vascular dementia might have mild problems with reasoning, concentration and speed of thinking. Later on, people with vascular dementia can become more confused and disoriented, finding it hard to walk and keep balance. Memory problems may also develop, alongside changes in mood, personality and increasing slowness of thought. As vascular dementia becomes advanced, people have much less awareness of what is happening around them, with increasing frailty and difficulties eating and walking without help.
Dementia with Lewy bodies
Dementia with Lewy bodies is the third most common type of dementia, thought to account for 10-15% of all cases of dementia. Dementia with Lewy bodies (DLB) is named after the damaging protein deposits that cause the disease, known as Lewy bodies. These deposits are made up of a protein called “alpha-synuclein”, and are also a pathological feature of Parkinson’s disease.
Symptoms of dementia with Lewy bodies
Similar to other types of dementia, the way someone with DLB is affected by the disease will depend on which brain areas are damaged. Frequently reported symptoms in the early stages of DLB are visual hallucinations, sleep problems and changes in concentration, attention and mood. These symptoms can come and go unpredictably. People with DLB may also experience movement problems, such as tremors, muscle rigidity, loss of coordination, and a shuffling walk. As DLB progresses, people often develop problems with memory loss, and may have trouble regulating body functions such as blood pressure and temperature.
Frontotemporal dementia is relatively rare compared to Alzheimer’s and vascular dementia. Unlike more common types of dementia, which occur more frequently with increasing age, frontotemporal dementia tends to start at a younger age (40-65 years).
In frontotemporal dementia, the frontal and temporal lobes of the brain become damaged. Like many other types of dementia, this damage is partly caused by the abnormal build-up of proteins in the brain. When the frontal lobes are damaged, this leads to a form of frontotemporal dementia (FTD) known as “behavioural variant FTD”. When the damage is mainly confined to the temporal lobes, this leads to a type of FTD known as “primary progressive aphasia”.
Symptoms of frontotemporal dementia
People with behavioural variant FTD often have trouble controlling their behaviour, and may say inappropriate things or become emotionally withdrawn. These behavioural changes become more pronounced and unmanageable as the disease progresses. Language and memory are usually not affected until the late stages of disease.
People with primary progressive aphasia often experience problems with speech and language. They may forget the meaning of words, speak differently, or say the opposite of what they mean. As well as gradually losing the ability to communicate, people with primary progressive aphasia may have delusions or hallucinations, experiencing memory loss and problems with day-to-day activities.
About 1 in 10 people with dementia are diagnosed with more than one type of dementia. This is called “mixed dementia”, and is most prevalent in people over 75 years of age.The most common mixed dementia is a combination of Alzheimer’s and vascular dementia, followed by a combination of Alzheimer’s and Lewy body dementia.
Symptoms of mixed dementia
The way a person is affected by mixed dementia will vary depending on the way each underlying disease affects their brain. So, their symptoms may include features of Alzheimer’s dementia – such as memory loss – alongside problems with processing thoughts, linked to vascular dementia. Like all forms of dementia, mixed dementia is a life-limiting disease that progressively worsens over time.
Young onset dementia
When a person develops dementia before the age of 65, this is known as “young onset dementia”. Recent reports suggest that young onset dementia is much more common than originally thought, with an estimated 159 per 100,000 people in Europe affected by the disease.
Young onset dementia encompasses all types of dementia. Although Alzheimer’s disease remains the most common cause of young onset dementia, other types of dementia are more common in younger people than in older adults, such as frontotemporal dementia and rare forms of dementia linked with Down’s syndrome.
Symptoms of young onset dementia
About 5% of people with Alzheimer’s dementia are diagnosed before the age of 65. People with young onset Alzheimer’s dementia often experience slightly different symptoms to those with late onset Alzheimer’s dementia. They are more likely to have problems with understanding visual information, language and with decision-making. As the disease progresses, symptoms are similar to those experienced by people with late onset Alzheimer’s dementia.