Study on rare dementia helps map the emotional brain
A NeuRA study published in the journal Brain has found that individuals diagnosed with corticobasal syndrome (CBS), a rare form of dementia, experience widespread deficits in emotion processing.
Scientists at NeuRA studied patients diagnosed with CBS and found that they show profound deficits in recognising emotions, such as distinguishing a frown from a grimace, or a look of shock, as well as difficulty understanding how other people are feeling.
Senior author of the study, Assoc Prof Olivier Piguet says, “Despite its pathological overlap with frontotemporal dementia, emotion processing in corticobasal syndrome hasn’t been systematically explored before. This study sheds light on the disease and gives us a greater understanding of how emotion is processed in the brain.”
“Corticobasal syndrome typically presents as a motor disturbance. Behaviour and cognitive changes tend to be ignored given the prominence of physical symptoms such as alien limb syndrome.”
This study reveals, for the first time, profound emotional impairments in CBS which are more severe than those seen in Alzheimer’s disease, the most common form of dementia. The severity of these emotion processing deficits were associated with atrophy in the basal ganglia, a structure deep within the brain, which is also involved in motivation and motor control.
Disturbed emotion processing and difficulty with social interactions have been previously reported in other dementias, and have a significant impact on day-to-day life. They are characteristic of frontotemporal dementia, and less so of Alzheimer’s disease, reflecting their different patterns of brain neurodegeneration across dementias.
First author of the study, Dr Fiona Kumfor, says, “Although there is no treatment for CBS, therapy does help to manage symptoms. The results of our study will help CBS patients and families better understand their condition, particularly how it affects mood and behaviour.”
Motor symptoms of CBS are similar to those found in Parkinson disease, such as:
- Akinesia/bradykinesia – an absence or slowness of movements; lack of spontaneous movements
- Rigidity -a resistance to imposed movement
- Tremor, often complex
Limb dystonia – abnormal posture of the extremities
These cognitive symptoms may be associated with CBD (though not all are seen in all patients):
- Alien hand syndrome in which the patient does not recognize the actions of his hand and can’t control movement of the hand or arm;
- Apraxia – the loss of the ability to make familiar, purposeful movements, manifested as difficulty using familiar objects or doing familiar things. Examples include using utensils, combing one’s hair, and dressing;
- Acalculia – difficulty carrying out simple calculations, such as adding and subtracting.
- Visual-spatial impairment – an individual with corticobasal degeneration may have difficulty orienting objects in space.