Professor Kim Graham is Professor of Cognitive Neuroscience and Dean of Research in the College of Biomedical and Life Sciences at Cardiff University. She is on the Steering Group of the Dementias Platform UK, and author of an Oxford University Press book entitled, ‘The Evolution of Memory Systems’. Her research group uses advanced neuroimaging methods, available at the Cardiff University Brain Research Imaging Centre, to study brain networks involved in dementia.
She describes different forms of dementia and the key signs to look out for.
All forms of dementia involve a decline in one or more forms of cognition; this could be a change in the ability to concentrate or difficulties remembering the names of people, objects or facts about the world. It could be struggling to recall details from a recent holiday or finding it harder to judge distances. Sometimes we see changes in emotion, motivation and sensitivity to others. While at first these cognitive changes may have only a small impact on daily life, in time they become more obvious, increasingly reducing the ability of the person with dementia to perform everyday activities.
In all dementias, this progressive worsening of cognition, whether it is memory, attention or language, is caused by damage to the brain. As the dementia progresses, cognition gets worse because the damage to the brain spreads. This may cause greater difficulties in the cognitive domain already affected (eg, more forgetfulness) or an increase in the range of cognitive problems experienced, such as social and behavioural changes alongside memory problems.
While we don’t fully know what causes dementias, we do know that they are not all caused by the same thing. In some dementias, such as vascular dementia, damaged blood vessels affect blood flow and cause a lack of oxygen to the brain. This results in brain damage which slows down thinking and results in difficulties concentrating for long periods of time. Vascular dementia is the second commonest form of dementia. In other dementias, such as Creutzfeldt-Jakob disease, infectious proteins called prions attack and damage the brain. Dementia can also be seen in people with HIV (human immunodeficiency disorder), and in this case, treatment with antiretroviral drugs can stop cognitive symptoms progressing. Repeated heavy drinking on a regular basis over many years can also result in alcoholic dementia. Alcohol is toxic to brain cells, and heavy drinking can also result in low levels of vitamin B1 (thiamine), which damages the brain. Stopping drinking alcohol can reverse or halt any cognitive changes in this form of dementia.
Dementia is most often seen in older age. These forms of dementia often present with quite different cognitive symptoms. We get these differences because each dementia affects different parts of the brain. These brain areas support different forms of cognition.
Dementias in old age
In the most common dementia of older age, Alzheimer’s disease, patients find remembering day-to-day events increasingly difficult. They are likely to get lost, especially in unfamiliar environments, and may repeat information or questions. We think Alzheimer’s disease may be caused by burn-out of a brain network involved in memory. This burn-out does not initially cause cognitive difficulties, but results in a toxic build-up of proteins which start to damage nerve cells. As these proteins build-up, this brain network can no longer function as well as before, and memory starts to fail.
Dementia with Lewy Bodies (tiny deposits of a protein that appear in nerve cells in the brain) shares some symptoms with Alzheimer’s disease and often causes difficulties with attention, which can come and go. Some people will see things that are not present (a visual hallucination) and some may suffer with delusions where they have thoughts that are not true, such as thinking that their spouse is an imposter. Problems with balance and movement are also common and can lead to falls. These movement difficulties are like those seen in Parkinson’s disease.
Frontotemporal dementia, also called Pick’s disease, has many different forms depending upon whether the frontal or temporal lobes of the brain are affected. When the frontal lobes are involved (frontal variant frontotemporal dementia) patients can show changes in their social skills, motivation and emotions. Patients often become less interested in activities which they normally enjoyed or have less understanding of other people’s feelings. They can also take up new activities which previously they showed no interest in. When the temporal lobes are affected (temporal variant frontotemporal dementia) we see difficulties in language, such as remembering the name for previously familiar people and objects. In this dementia, patients show a dramatic ongoing loss of knowledge about the world and become unable to provide information about common animals, objects and people, getting confused between items that come from the same category (eg, mixing up cow, pig and sheep). In the early stages of temporal variant frontotemporal dementia, patients are often able to remember details of past events, unlike patients with Alzheimer’s disease.
Cognitive clues and diagnosis
The different cognitive symptoms seen in each of these dementias provide important clues to help doctors make effective diagnoses. By testing memory, language, attention and perception, and measuring motor function and balance, doctors can identify the type of dementia and provide the right medical advice. This can also help carers, families and friends know how best to support their loved ones.