Compensatory brain mechanism in patients with Parkinson's disease
Patients suffering from Parkinson's disease showed no deficits in their ability to recognise emotions, while this ability was expected to be compromised. This is due to a shortage of the 'happiness hormone' dopamine. Reduced brain activity in the emotional system should disrupt the ability to identify emotions. However, according to PhD research conducted by Anja Moonen at Maastricht UMC+, the brain compensates for this reduction. The PhD candidate also found that a reduction in the amount of grey matter in the brains of Parkinson's patients is an important indicator of deteriorating cognitive abilities.
Parkinson's disease kills cells in the deeper-lying parts of the brain that are involved in the production of dopamine, among other things. This 'happiness hormone' also controls muscles and regulates emotions. Dopamine deficiency leads to the characteristic Parkinson's symptoms, such as shaky arms and legs, muscle stiffness and slow movements. 'People tend to focus on the physical symptoms,' says Moonen, 'and pay far less attention to cognitive and emotional problems. But these problems can have a massive impact on the well-being of the patients, their friends and their family.'
Compensatory mechanism
In a series of behavioural experiments, Moonen found that Parkinson's patients were just as capable of recognising positive and negative emotions as healthy people. MRI scans found reduced activity in certain parts of the brain, possibly due to a dopamine deficiency, and increased activity in other parts. This activation is thought to compensate for the decreased ability to perceive emotions and process information. Moonen also investigated cognitive ability in Parkinson's patients in relation to the amount of grey matter in the brain. There, too, she found a notable link.
Grey matter
Grey matter is a collective term for the cells in the nervous system involved in processing information. In a follow-up study, Moonen found that a reduction in grey matter did not impair cognitive ability. 'A reduction in grey matter may be the first sign that cognitive ability will decline in the future,' says Moonen. 'This finding highlights the importance of monitoring patients at an early stage and prescribing medication and cognitive therapy as soon as possible to minimise further deterioration. These fundamental insights into the brain processes of Parkinson's patients are essential for developing new therapies tailored specifically to this target group.'
Anja Moonen of the research institute MHeNS received her PhD from Maastricht University on 24 March. ‘Emotion and Cognition in Parkinson’s disease: etiology and neurobiological mechanisms’
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