People with Parkinson’s Disease (PD) have impaired emotional recognition and expression compared to healthy people, a new study shows.

The study, titled “Altered emotional recognition and expression in patients with Parkinson’s disease,” was published in the journal Neuropsychiatric Disease and Treatment.

While Parkinson’s Disease is generally characterized as a movement disorder, many people with the disease tend to exhibit cognitive and emotional impairment as it progresses. The pathology of the disease affects certain regions of the brain, such as the basal ganglia, thalamus, and prefrontal cortex, which are involved in cognitive and emotional function.

One particular aspect that seems to be impaired in Parkinson’s patients is emotional recognition, which includes recognition of emotional faces and voices. In addition to emotional recognition, the ability to express emotions, including expression of emotional faces and voices, is also reduced in Parkinson’s patients. This is detrimental because as the disease progresses, patients need to have complete emotional cognitive ability to communicate effectively with their caregivers.

That led Chinese researchers to set out to determine emotional processing in patients with Parkinson’s Disease.

Deep-brain stimulation, a surgical treatment for Parkinson’s, has been suggested as leading to deficits in emotional processing if the surgical site is the subthalamic nucleus . So researchers recruited PD patients who had not undergone the surgery to determine their emotional processing by using both visual and auditory techniques.

Emotional recognition of patients was determined by the Karolinska Directed Emotional Faces database 50 Faces Recognition test and the Montreal Affective Voices database 50 Voices Recognition test.

The emotional facial expression was determined by asking participants to imitate five emotions including neutral, happiness, anger, fear, and sadness. The emotional voice expression was determined by asking participants to express nonverbal vocalizations of the five emotions.

Results showed that the Parkinson’s Disease patients group had significantly lower scores for both emotional recognition and expression compared to healthy patients in terms of reaction time and confidence level.

“Our data provide novel information on altered emotional processing in pre-(deep-brain stimulation) PD using two sensory modalities,” the authors write. “The PD group exhibited poorer performance on both the recognition and expression tasks.”

Researchers also found that participants from both groups who scored low on emotional recognition also scored lower on emotional expression, while patients who scored high on emotional recognition also scored higher on emotional expression. This finding suggests that emotional recognition and expression may share a common nervous system, the researchers wrote.