Parkinson’s disease and DBS – one year on

The Irish Neurological Association 2026 Annual Conference heard from Dr Neil Austin, Neuropsychologist with the All-Island Deep Brain Stimulation (DBS) Service and the Dublin Neurological Institute at the Mater Misericordiae University Hospital.

He delivered a presentation titled ‘One year on: Neuropsychologist profile of cognitive changes following subthalamic nucleus DBS in Parkinson’s disease (PD)’.

Dr Austin explained that DBS is a recognised treatment for PD, providing significant motor improvement, but with varying clinical outcomes.

“Cognitive dysfunction is common in PD and may influence surgical decisions and post-operative recovery,” said Dr Austin.

Cognitive dysfunction is common
in PD and may influence surgical decisions and post-operative recovery

“Therefore, comprehensive post-operative cognitive assessments help to identify baseline deficits and their relation to post-DBS cognitive changes.”

Global cognition often remains stable post-surgery; however, subtle declines in executive function and processing speed may occur, he explained. This prompted his work with colleagues to examine cognitive changes, from pre-operative assessment, to 12 months post-subthalamic nucleus DBS implantation.

Dr Austin provided a brief overview of the DBS procedure and the multidisciplinary team (MDT) involved in providing PD care in his clinic. Patients who are deemed suitable candidates are referred to the MDT for assessment and evaluation.

“All these assessments are to determine that we will be able to help these candidates without harming them,” Dr Austin told the conference.

“Subtle impairment is common in PD, and mild cognitive impairment is at around 20 to 30 per cent at diagnosis,” said Dr Austin.

“Attentional difficulties are really common and inefficient learning and poor free recall, although recognition memory is near normal. There is also often bradyphrenia and compromised executive functioning, poor verbal fluency, flexibility and abstraction, which can clinically manifest as apathy.”

There is also impaired visuo-spatial perception and impaired non-verbal rather than verbal reasoning, he added.

In the study, 70 people with PD under consideration for DBS underwent extensive tests exploring executive functioning, memory, attention, visuo-spatial perception, verbal and non-verbal reasoning, and global cognition, both pre-operatively and 12 months post-operatively.

“While global cognitive function remained stable following DBS, indicating preserved cognitive integrity, selective declines were noted in processing speed and verbal fluency 12 months post-operatively,” Dr Austin said of the results.

“Immediate memory encoding showed a post-operative decline, while delayed recall remained stable, indicating preserved consolidation capacity.

“Such findings indicate subtle changes within frontal-executive networks, despite largely unaffected global cognition in the early post-operative phase.”