Sentence completion in progressive supranuclear palsy following transcranial direct current stimulation

Area of Science:

• Neuroscience
• Neurology
• Speech and Language Therapy

Background:

• Progressive Supranuclear Palsy (PSP) is a neurodegenerative disease causing motor and cognitive decline, including impaired word retrieval.
• Current understanding of brain stimulation's effect on sentence-level language processing in PSP is limited.
• Previous studies suggest transcranial direct current stimulation (tDCS) may improve word fluency in PSP.

Purpose of the Study:

• To investigate the effectiveness of anodal tDCS (atDCS) applied over the left Broca's area for improving sentence completion time in PSP patients.
• To compare the effects of atDCS on sentence completion in PSP patients versus those with multiple system atrophy (MSA) and healthy elderly individuals.

Main Methods:

• A sham-controlled, triple-blinded crossover study involving 23 PSP patients.
• Application of anodal tDCS (2 mA for 20 min) over the left Broca's area.
• Comparison of sentence completion times between active tDCS and sham conditions, and between PSP, MSA, and healthy control groups.

Main Results:

• Sentence completion time significantly improved in PSP patients during active atDCS compared to sham.
• No significant improvement in word fluency was observed with this specific electrode placement, unlike previous studies.
• A notable difference in response to atDCS was observed between PSP patients and both MSA patients and healthy elderly individuals.

Conclusions:

• Anodal tDCS applied to the left Broca's area can enhance sentence completion in individuals with Progressive Supranuclear Palsy.
• This finding highlights a potential neurophysiological difference between PSP and MSA, particularly in language processing.
• Targeted brain stimulation over Broca's area shows promise for improving language deficits in PSP, potentially aiding in the development of specialized speech and language therapies.