5. Dementia with Lewy bodies
Dementia with Lewy bodies gets its name from microscopic deposits that are found in the brains of people with the condition. These deposits cause damage to, and the eventual death of, nerve cells in the brain. Dementia with Lewy bodies develops slowly and tends to progress gradually, like Alzheimer’s disease.
Parkinson’s disease is also caused by Lewy bodies and some symptoms of this disease are shared with dementia with Lewy bodies. Early symptoms of this type of dementia may also overlap with those of Alzheimer’s disease, but there are several important differences.
Unlike Alzheimer’s disease, in the early stages of dementia with Lewy bodies the person’s attention and alertness often vary widely from day to day, or even during the course of a single day. This can often be puzzling for those around them.
Most people with dementia with Lewy bodies also have recurrent visual hallucinations. These are much more common than in early Alzheimer’s disease and are very detailed, often of animals or people. Misperceptions and auditory hallucinations (hearing sounds that are not real) are also very common. These symptoms may explain why people with this dementia often falsely believe that they are being persecuted.
Half or more of those affected by dementia with Lewy bodies have movement problems when the dementia is diagnosed, and this proportion increases as dementia progresses. These symptoms are like those of Parkinson’s disease, such as slowness of movement, stiffness and sometimes tremor. The person may also have difficulty judging distances and be prone to problems with balance, falls and fainting.
As dementia with Lewy bodies progresses, some of the symptoms become more like those of middle or late stage Alzheimer’s disease, including greater problems with day-to-day memory and behaviours that challenge, such as agitation, restlessness or shouting out. Worsening of Parkinson-type symptoms means that walking gets slower and less steady. The risk of falls remains high. The combination of symptoms in a person with dementia with Lewy bodies can be particularly stressful for family and carers.
After the symptoms of dementia with Lewy bodies begin, people live on average for six to twelve years. However, each person will experience dementia with Lewy bodies differently. For more information see our page on dementia with Lewy bodies.