Dementia is an umbrella term for several types of cognitive impairment. Alzheimer’s Disease is by far the most common form of dementia, comprising about 70% of all dementia cases:
Proceed to this page for more information on Alzheimer’s and Mild Cognitive Impairment (MCI).
Other Dementia Types Include:
Vascular dementia describes impairments in cognitive function caused by problems in the blood vessels that feed the brain. In some cases, a blood vessel may be completely blocked, causing a stroke. Some strokes result in dementia while others don’t. It depends on the severity of the stroke and the portion of the brain that’s affected. Vascular dementia also can occur when blood vessels in the brain narrow, reducing the amount of blood flow to those sections of the brain. The prevalence of vascular dementia ranges from 1 percent to 4 percent in people over the age of 65. The risk increases dramatically with age.
Dementia with Lewy Bodies
Dementia with Lewy bodies (DLB) is one of the most common types of progressive dementia. The central feature of DLB is progressive cognitive decline, combined with three additional defining symptoms: (1) pronounced “fluctuations” in alertness the and attention, such as frequent drowsiness, lethargy, lengthy periods of time spent staring into space, or disorganized speech; (2) recurrent visual hallucinations; and (3) parkinsonian motor symptoms, such as rigidity and the loss of spontaneous movement. People may also suffer from depression.
The symptoms of DLB are caused by the build-up of Lewy bodies – accumulated bits of alpha-synuclein protein — inside the nuclei of neurons in areas of the brain that control particular aspects of memory and motor control. The similarity of symptoms between DLB and Parkinson’s disease, and between DLB and Alzheimer’s disease, can often make it difficult for a doctor to make a definitive diagnosis.
In addition, Lewy bodies are often also found in the brains of people with Parkinson’s and Alzheimer’s diseases. These findings suggest that either DLB is related to these other causes of dementia or that an individual can have both diseases at the same time. DLB usually occurs sporadically, in people with no known family history of the disease. However, rare familial cases have occasionally been reported.
Frontotemporal dementia (frontotemporal lobar degeneration) is an umbrella term for a diverse group of rare disorders that primarily affect the frontal and temporal lobes of the brain — the areas generally associated with personality and behavior.
In frontotemporal dementia, portions of these lobes atrophy, or shrink. Signs and symptoms vary, depending upon the portion of the brain affected. Some people with frontotemporal dementia undergo dramatic changes in their personality and become socially inappropriate, impulsive or emotionally blunted, while others lose the ability to use and understand language.
Frontotemporal dementia is often misdiagnosed as a psychiatric problem or as Alzheimer’s disease. But frontotemporal dementia tends to occur at a younger age than does Alzheimer’s disease, typically between the ages of 40 and 70. And the memory problems associated with Alzheimer’s disease are not as prominent in the early stages of frontotemporal dementia.
The term FTD as a ‘general term’ can also be referred to as:
- Pick’s Disease
- Frontotemporal Lobar Degeneration
- Progressive Aphasia
- Semantic Dementia
Parkinson’s Disease (PD) belongs to a group of conditions called motor system disorders, which are the result of the loss of dopamine-producing brain cells. Approximately 20% of people with Parkinson’s disease will develop dementia, usually after the age of 70.
The four primary symptoms of PD are tremor, or trembling in hands, arms, legs, jaw, and face; rigidity, or stiffness of the limbs and trunk; bradykinesia, or slowness of movement; and postural instability, or impaired balance and coordination. As these symptoms become more pronounced, patients may have difficulty walking, talking, or completing other simple tasks. PD usually affects people over the age of 50.
Early symptoms of PD are subtle and occur gradually. In some people the disease progresses more quickly than in others. As the disease progresses, the shaking, or tremor, which affects the majority of PD patients may begin to interfere with daily activities. Other symptoms may include depression and other emotional changes; difficulty in swallowing, chewing, and speaking; urinary problems or constipation; skin problems; and sleep disruptions. There are currently no blood or laboratory tests that have been proven to help in diagnosing sporadic PD. Therefore the diagnosis is based on medical history and a neurological examination. The disease can be difficult to diagnose accurately. Doctors may sometimes request brain scans or laboratory tests in order to rule out other diseases.