Inability To Express Emotion May Be An Early Symptom Of Parkinson's Disease

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Main Category: Parkinson's Disease
Also Included In: Psychology / Psychiatry
Article Date: 24 Jan 2012 - 10:00 PST

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Alexithymia, a person's state of deficiency in understanding, processing, or describing emotions, has been strongly linked to depression in both clinical and general populations, and even though symptoms of alexithymia and depression can be partially overlapping, they are not all related to depressive symptoms and therefore highlight the relative independence of the two disorders. For instance, Parkinson's disease (PD) is a clinical condition that is often indicated by depression and an altered emotional processing. About 21% of medicated PD patients have alexithymia related to depression.

Given that affective symptoms may precede the clinical motor onset of PD, it is of particular interest to investigate alexithymia in newly diagnosed untreated (de novo) PD patients prior to starting dopaminergic therapy.

The researchers set out to assess the prevalence of alexithymia in de novo PD patients and its association with depression. For their study, the researchers assessed 42 de novo PD patients and 30 age-matched healthy controls (HC) according to the Twenty-Item Toronto Alexithymia Scale (TAS-20) and the Geriatric Depression Scale Short Form (GDS-15).

They enrolled the de novo PD patients in two Italian movement disorder tertiary clinics at the Versilia Hospital in Viareggio and at the Neurological Clinic at the University of Pisa where they measured the severity of motor symptoms by using the Unified Parkinson's Disease Rating Scale (UPDRS II and III). The global cognitive status in both patients groups was assessed with the Mini-Mental State Examination (MMSE).

The TAS-20 total score categorized the participants as nonalexithymic for scores between 20 to 51, as borderline alexithymic with scores ranging from 52 to 60, or as alexithymic if the score was equal to or greater than 61.

They found no differences between the de novo PD patients and the healthy controls in terms of age, education, cognitive status (MMSE), alexithymia (TAS-20 score) and depression (GDS-15 score), however they did establish a statistically important difference for the TAS-20 subscale F2 (p = 0.07), with cutoff scores of the TAS-20 identifying 10 alexithymic patients (23.80%) in the de novo PD patient group compared with 5 (16.6%) patients in the HC group, whilst 11 patients in the de novo PD group (26.19%) were borderline alexithymic compared with 7 patients (23.3%) in the HC control group and 21 patients being established as nonalexithymic (50.01%) in the de novo PD group compared with 18 patients (60.1%) in the HC group.

The researchers detected no statistical difference (p =0.33) in alexithymia frequency between de novo PD patients (23.80%) and the healthy controls (16.6%). Alexithymic patients of either participant group were more depressed at the GDS-15 compared with nonalexithymic or borderline alexithymic subjects (p <0.01), whilst borderline alexithymic participants were more depressed compared with those who were nonalexithymic (p <0.01).

The paramount finding of the study is that alexithymia is linked to depression in de novo PD patients (23.8%). Given that 26% of de novo PD patients rated as borderline scores on the TAS-20, one can reason that approximately half of the PD patients may have mild to severe difficulties in affect regulation since the early clinical stages of the disease.

Considering that the prevalence of alexithymia is comparable between the de novo PD group and HCs indicates that the dopamine depletion that precedes the clinical motor onset of PD has hardly any impact on alexithymia. Furthermore, the findings revealed that male patients were more alexithymic but not more depressed than female patients, which confirms that alexithymia and depression partially overlap even though they are independent affective disorders.

In summary, this brief report indicates that an early neuropsychiatric assessment of affect regulation difficulties in PD patients proves to be beneficial.

Written by Petra Rattue
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