Overview of brain structure and function in FTD
Topography of the brain
The brain is made of two halves, the “hemispheres”, which are connected by a thick bundle of nerve fibres. The hemispheres can be divided into four main regions or lobes. The diagram below (Click picture to enlarge) shows the left hemisphere with the lobes highlighted in different colours: frontal (blue), temporal (green), parietal (yellow) and occipital (pink). Another important brain structure, the hippocampus, is buried within the temporal lobe and is not visible in this diagram. The hippocampus plays a central role in the formation of new memories.
Organisation of the brain
Each lobe is composed of an outer layer (“the grey matter”) and an inner layer (“the white matter”). The grey matter is where the nerve cells, or neurons, reside. The neurons are the source of information within the brain. The neurons are what allows us to think, reason, learn and feel. In contrast, the white matter consists of connecting fibres. These fibres transmit information among neurons within or across different brain regions.
Functions of the brain
Each lobe of the brain supports one or several thinking abilities, such as memory, language or emotion processing. The function(s) of each lobe are summarised in the diagram. In recent years, functional neuroimaging (e.g., PET or fMRI) has revealed that a particular function commonly involves multiple brain regions. In other words, similar to the close structural connections that exist across different brain regions and between the hemispheres, close functional relations across regions are also present within the brain.
Brain changes with dementia
In the event of dementia, diseases affecting the brain such as frontotemporal dementia and Alzheimer’s disease, various pathological processes take place as the disease unfolds. These changes, which can only be seen under the microscope, include loss of nerve cells and abnormal accumulation of protein in and around the cells. The kind(s) and severity of changes in the brain, as well as the location in which they occur, is specific for each dementia type.
In frontotemporal dementia, as the name suggests, pathology may be present in the frontal lobes, the temporal lobes or both. The regions that are most vulnerable to the disease are shown in dark in the diagram above. As the disease progresses, these brain regions show shrinkage, which is noticeable on brain imaging.
Deficits in frontotemporal dementia
Deficits associated with frontotemporal dementia are varied and depend on the location and severity of pathology in the brain. Most common deficits are changes in behaviour and personality, difficulty relating to other people and difficulty organising day‐to‐day activities. In these patients, the underlying brain changes affect predominantly the frontal lobes (Behavioural- variant FTD). In contrast, other patients show change in language proficiency, either in the form of a difficulty understanding the meaning of words (Semantic Dementia), or a difficulty using the correct words (Progressive Non-fluent Aphasia) . This may be accompanied by a difficulty judging emotional state in self and others accurately. In these patients, the pathology is more pronounced in the anterior portion of the temporal lobe, or in the region where the frontal lobe meets the parietal and temporal lobes. Over time, and as the disease progresses, pathology tends to become more diffuse. As a consequence, clinical presentations tend to merge and deficits become more pronounced.
Managing frontotemporal dementia
Not uncommonly, individuals with frontotemporal dementia show a limited awareness of their deficits in thinking and changes in behaviour and a reduced understanding of the impact of their condition on friends and families. This limited insight may create significant challenges for carers. Although each situation is unique, a number of simple guidelines may be helpful. First, carers need to recognise that behavioural changes are the result of changes in the brain. In most instances, the person is not being difficult intentionally. As such, direct confrontation to change a difficult or inappropriate behaviour is unlikely to be successful. You are more likely to succeed by changing the environment, for example by redirecting attention or removing what triggered the behaviour, than by trying to change the person.
In individuals where language deficits are the most prominent symptoms, difficulty understanding others or being understood by others may result in frustration. Simple, rather than complex, commands or instructions and the use of simple words are likely to improve comprehension. Use of visual supports, such as drawings or photos, may also be helpful in situations where verbal expression is disrupted.
