Trihexyphenidyl (marketed as Artane and others) is an antispasmodic drug used to treat stiffness, tremors, spasms, and poor muscle control. It is an agent of the antimuscarinic class and is often used in management of Parkinson's disease. It was approved by the FDA for the treatment of Parkinson's in the US in 2003.
Artane has been shown to have several sides effects, some similar to Parkinson's symptoms, in particular people who are older or who have psychiatric conditions may become confused or develop delirium.
Despite growing concerns about Trihexyphenidyl causing cognitive decline in tremor-dominant Parkinson disease patients, the underlying neural correlates remain unclear. Therefore, the authors investigated the effects of this drug on prefrontal executive function and spontaneous neural activity in patients with tremor-dominant Parkinson disease by utilizing functional near-infrared spectroscopy.
The authors recruited 30 patients with tremor-dominant Parkinson disease, including 15 patients receiving the treatment and 15 patients not receiving Trihexyphenidyl.
The researchers performed comprehensive neuropsychological and clinical assessments to evaluate each patient's cognitive function, mental status, and clinical symptoms.
They measured brain activation elicited from the verbal fluency task and changes in amplitude of low-frequency fluctuations at rest to investigate executive function and spontaneous neural activity, respectively. In addition, the authors examined the relationship between altered activation during task and resting state and neuropsychological and clinical data.
Compared with tremor-dominant Parkinson disease patients not taking Trihexyphenidyl, tremor-dominant Parkinson disease patients taking the treatment showed no differences on neuropsychological tests.
However, there was insufficient activity of the dorsolateral prefrontal cortex, ventrolateral prefrontal cortex, and the orbitofrontal cortex related to the frontoparietal network at rest.
Furthermore, functional near-infrared spectroscopy results were positively correlated with scores of multiple cognitive domain functions.
These findings suggest that Trihexyphenidyl treatment may lead to prefrontal dysfunction in tremor-dominant Parkinson disease patients, attenuating brain activation in executive function and cognition-related spontaneous neural activity.