Altered Emotional Capability Possibly Linked to Atypical Form of Parkinson

Alexithymia—the inability of recognizing and verbalizing emotions and distinguishing them from bodily sensations—may be identifiable early on in patients with progressive supranuclear palsy with predominant parkinsonism (PSP-P) and PSP with Richardson’s syndrome (PSP-RS), according to a recent study.

The study, published by Brain and Behavior, aimed to evaluate the qualitative and quantitative differences of alexithymia and anhedonia—the lowered ability to experience physical and social pleasure—in PSP-RS and PSP-P patients as compared with patients who have Parkinson disease (PD).

The researchers recruited 55 PD patients, 11 PSP-P patients, and 14 PSP-RS patients, who underwent clinical neuropsychiatric, and neuropsychological evaluations. The Toronto Alexithymia Scale‐20 item (TAS‐20) was used to assess alexithymia, while hedonic tone was evaluated by the Snaith-Hamilton Pleasure Scale (SHAPS).

“Emotional processing and hedonic state modulate behavior by regulating mechanisms of motivation, promoting transgenerational relationships, and increasing chances to adapt to communities,” explained the authors. “Alexithymia and anhedonia have been reported frequently in patients suffering from Parkinson's disease (PD); however, it is still not clear whether they are a secondary phenomenon linked to depression and apathy severity or a disease primary characteristic linked to frontal lobe dysregulation.”

The results revealed that the frequency of alexithymia diagnosis was greater in PSP-P and PSP-RS patients than in PD patients. In addition, based on the TAS-20 scores, PSP-RS performed worse in the total score when compared to PD. When comparing patients with depression, the results suggested that PSP-RS demonstrated higher scores in TAS-20 total and TAS-20 F2 than PD, while there were no significant differences among non-depressed patients. Also, SHAPS scores did not significantly vary.

“These findings support the idea that impairment in processing and organizing emotional experiences mirrors a basic neurophysiological dysfunction occurring precociously in depressed PSP subjects. Therefore, the identification of alexithymia could orient the diagnosis toward PSP cases; particularly, difficulty in describing feelings could help to identify PSP‐RS patients,” concluded the authors. “Our findings support the evidence that comprehensive psychiatric evaluations might be useful for diagnostic and therapeutic processes of PSP patients since the early stages of the disease.”

The researchers concluded that altered emotional capability may be related to specific neurophysiological dysfunction occurring in PSP, which could help diagnoses in PSP cases.

Reference

Assogna F, Pellicano C, Cravello L, et al. Alexithymia and anhedonia in early Richardson's syndrome and progressive supranuclear palsy with predominant parkinsonism [published online November 19, 2019]. Brain and Behavior. doi: 10.1002/brb3.1448.