Alexithymia associated with depression in de novo PD patients

Jan 23 2012

Alexithymia has been found to be strongly associated with depression in both general and clinical populations. Alexithymic and depressive symptoms may be partially overlapping, but not all are correlated with depressive symptoms, thus underlining the relative independence of the two disorders. Parkinson's disease (PD) is a clinical condition often characterized by depression and an altered emotional processing. In medicated PD patients alexithymia has a prevalence of 21% and is related to depression.

The investigation of alexithymia in newly diagnosed untreated (de novo) PD patients before the administration of dopaminergic therapy is of particular clinical interest considering that affective symptoms may precede the clinical motor onset of PD. This study was aimed at investigating the prevalence of alexithymia in de novo PD patients and its relation to depression. To estimate the prevalence of alexithymia and its relation to depression in de novo PD patients the Twenty-Item Toronto Alexithymia Scale (TAS-20) and the Geriatric Depression Scale Short Form (GDS-15) to 42 de novo PD patients and 30 age-matched healthy controls (HC) were administered.

The de novo PD patients were enrolled in two Italian movement disorder tertiary clinics (Versilia Hospital, Viareggio; Neurological Clinic, University of Pisa). The severity of motor symptoms was measured by the Unified Parkinson's Disease Rating Scale (UPDRS II and III). In all enrolled subjects the global cognitive status was assessed with the Mini-Mental State Examination (MMSE). The TAS-20 total score allowed categorizing subjects as nonalexithymic (scores ranging from 20 to 51), borderline alexithymic (scores ranging from 52 to 60), or alexithymic (scores ≥ 61). No differences were found for age, education, cognitive status (MMSE), alexithymia (TAS-20 score) and depression (GDS-15 score) between de novo PD patients and HC. A statistically significant difference was approached for the TAS-20 subscale F2 (p = 0.07). In the group of de novo PD patients, cutoff scores of the TAS-20 identified 10 alexithymic patients (23.80%), 11 borderline alexithymic patients (26.19%) and 21 nonalexithymic patients (50.01%).

In the group of HC, 5 subjects were alexithymic (16.6%), 7 subjects were borderline alexithymic (23.3%) and 18 were nonalexithymic (60.1%). The difference between frequencies of alexithymia in de novo PD patients (23.80%) and HC (16.6%) was not statistically different (p =0.33). Either in the sample of de novo PD patients or in the sample of HC, alexithymic subjects were more depressed at the GDS-15 than nonalexithymic or borderline alexithymic subjects (p <0.01) and borderline alexithymic subjects were more depressed than nonalexithymic subjects (p <0.01).

The main finding of this study is that alexithymia is associated with depression in de novo PD patients (23.8%). Considering that 26% of de novo PD patients reported borderline scores on the TAS-20, it may be argued that about half of the PD patients may present mild to severe difficulties in affect regulation since the early clinical stages of the disease. The finding that the prevalence of alexithymia is similar in de novo PD patients and in HC suggests that the dopamine depletion that precedes the clinical motor onset of PD scarcely impacts on alexithymia. The finding that male patients were more alexithymic but not more depressed than female patients confirms that alexithymia and depression are partially overlapping but independent affective disorders.

In conclusion, this brief report suggests the usefulness of an early neuropsychiatric assessment of affect regulation difficulties in PD patients.