How does the impact of DBS vary across Parkinson’s disease subtypes?

A new international study has examined whether deep brain stimulation (DBS) is more effective at tackling non-motor symptoms in certain subtypes of the condition

Deep brain stimulation (DBS) surgery involves inserting electrodes into the brain to change electrical signals associated with Parkinson’s symptoms – with the aim of improving quality of life for people living with the condition. But could DBS tackle non-motor symptoms more effectively in some people than in others?

Parkinson’s may be allocated to different subtypes depending on which motor symptoms are dominant. For example, in the ‘postural instability and gait disturbance’ (PIGD) subtype of the condition, difficulty walking and standing are the most prevalent symptoms, while the ‘tremor-dominant’ (TD) subtype is associated with tremor.

Now, researchers in Germany, the UK, Brazil and Italy have explored whether DBS might better support people with the PIGD subtype of Parkinson’s than those with the TD form of the condition. Their hypothesis? That those with the PIGD subtype – which has been reportedly linked to a higher burden of non-motor symptoms and worse quality of life – would experience “more beneficial non-motor effects” than the group with the TD subtype.

As part of their study, published in the journal ‘Parkinsonism & Related Disorders’, the team examined 130 people with Parkinson’s who had undergone DBS surgery at study centres in Germany and the UK between February 2012 and April 2021. Of these, 82 participants had the PIGD form of Parkinson’s, while 33 had the TD subtype and the remaining 15 had a mix of other types.

Using the Non-Motor Symptoms Scale (NMSS), the scientists analysed participants’ reported symptoms six months after receiving the treatment. They also examined changes in the participants’ quality of life, such as their ability to perform daily tasks.

Greater non-motor improvements observed in PIGD group

The NMSS scores revealed that DBS led to significant decreases in non-motor symptoms for participants with the PIGD subtype of Parkinson’s, including in areas of communication and daily living activity. The observed benefits were greater in the PIGD group than in the TD group.

“This study provides evidence of a favourable outcome of total non-motor burden in PIGD compared to tremor-dominant patients undergoing DBS for [Parkinson’s],” the researchers wrote.

In light of their findings, they recommended that larger studies with greater follow-up periods be conducted to further explore the area – and that greater attention be given to people’s individual symptoms. “These differences of clinical efficacy on non-motor aspects should be considered when advising and monitoring [people with Parkinson’s] undergoing DBS,” they concluded.

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