Hedonic tone and its mood and cognitive correlates in Parkinson's disease

Anhedonia in Neurodegenerative Diseases

Neurodegenerative diseases are increasingly recognised to be an important cause of brain disorders, particularly in late age. Associated with a wide range of pathologies, they lead to progressive loss of neurons in different regions of the nervous system. Although anhedonia is common in a variety of neurodegenerative diseases, to date it has not been extensively studied in most of these conditions. Here we review the current literature on studies assessing the association between anhedonia and neurodegenerative diseases including Parkinson's Disease, Dementia with Lewy Bodies, Parkinson's Plus Syndromes, Alzheimer's Disease, Vascular Dementia, Frontotemporal Dementia, Amyotrophic Lateral Sclerosis and Huntington's Disease. Much of the research has been conducted in Parkinson's disease where it is evident that there are strong links between apathy (loss of motivation) and anhedonia, although the two syndromes can be dissociated. Intriguingly, drugs that improve apathy can also lead to amelioration of anhedonia in some cases. Overlaps between the two syndromes may also exist across other neurodegenerative conditions, including Frontotemporal Dementia in which imaging has revealed atrophy of both common brain regions associated with anhedonia and apathy, as well as a set of unique brain regions associated with anhedonia. A transdiagnostic perspective might be helpful to investigate whether a common network of brain regions is dysfunctional with anhedonia across neurodegenerative conditions.

Effects of tDCS on reward responsiveness and valuation in Parkinson's patients with impulse control disorders

Parkinson's disease (PD) patients with impulse control disorders (ICD) frequently report hypersensitivity to rewards. However, a few studies have explored the effectiveness of modulation techniques on symptoms experienced by these patients. In this study, we assessed the effect of anodal tDCS over the DLPFC on reward responsiveness and valuation in PD patients with ICD. 43 participants (15 PD patients with ICD, 13 PD without ICD, and 15 healthy matched controls) were asked to perform a reward-craving test employing both explicit (self-ratings of liking and wanting) and implicit (heart rate and skin conductance response) measures, as well as two temporal discounting tasks with food and money rewards. Each participant performed the experimental tasks during active anodal tDCS of the left dorsolateral prefrontal cortex (DLPFC), anodal tDCS of the primary motor cortex (M1), and sham tDCS. Results showed increased wanting and a steeper temporal discounting of rewards in PD with ICD compared to the other groups. Moreover, we found that PD without ICD exhibit reduced liking for rewards. tDCS results capable to modulate the altered intensity of PD patients' liking, but not wanting and temporal discounting of rewards in PD patients with ICD. These findings confirm that alterations in reward responsiveness and valuation are characteristics of impulse control disorders in patients with PD but suggest that anodal tDCS over the left DLPFC is not capable to influence these processes. At the same time, they provide new insight into affective experience of rewards in PD.

Decreased emotional creativity and its relationship with cognitive functions in Parkinson's disease: A preliminary study

Patients with Parkinson's disease (PD) suffer from a wide range of non-motor symptoms, including cognitive deficits and impairment of emotional processing. The present study aimed to explore in PD patients compared to healthy adults the relationship between cognitive performance and emotional creativity (EC), defined as a set of cognitive abilities and personality traits related to originality and appropriateness of emotional experience. PD patients (n = 22) and healthy controls (n = 40) underwent a complex neuropsychological assessment and were administrated with the self-reported Emotional Creativity Inventory (ECI) questionnaire. To explore the relationship between cognitive tests and the ECI, a regression analysis was conducted. PD patients and healthy controls differed significantly in the EC component Preparedness as well as in the neuropsychological test battery scores. PD patients showed lower scores in cognitive tests and a lower score in Preparedness compared to healthy adults. The output of the regression analysis showed that the extent to which the neuropsychological tests relate to the ECI components is low.

Alexithymia and anhedonia in early Richardson's syndrome and progressive supranuclear palsy with predominant parkinsonism

INTRODUCTION

Phenotypic variants of progressive supranuclear palsy (PSP) are all characterized by the combination of motor symptoms of parkinsonism with a number of neuropsychiatric and cognitive disorders. Despite the strong effort in characterizing these features in PSP, alexithymia and anhedonia have not been investigated at present. Here, we aimed at investigating the qualitative and quantitative differences of alexithymia and anhedonia in the two more frequent variants of PSP, Richardson's syndrome (PSP-RS) and PSP with predominant parkinsonism (PSP-P) compared to Parkinson's disease (PD) patients recruited within 24 months after the onset of motor symptoms.

METHODS

One hundred fifty-five PD, 11 PSP-P, and 14 PSP-RS patients underwent clinical, neuropsychiatric, and neuropsychological evaluations. Alexithymia was assessed using the Toronto Alexithymia Scale-20 item (TAS-20), and hedonic tone was measured by the Snaith-Hamilton Pleasure Scale (SHAPS).

RESULTS

In PSP-P and PSP-RS patients, the frequency of alexithymia diagnosis was higher than in PD. On the TAS-20 scores, PSP-RS performed worse in the total score and in F2 sub-scale when compared to PD. Among patients with diagnosis of depression, PSP-RS showed higher scores in TAS-20 total and TAS-20 F2 than PD. No significant differences in TAS-20 scores were found in nondepressed patients. Finally, we did not find significant differences among PD, PSP-P, and PSP-RS groups in the SHAPS scores.

CONCLUSIONS

Alexithymia is identifiable very early in PSP-P and PSP-RS patients. Alexithymic symptoms differentiate PSP-RS group from PD group but not between the two subtypes of PSP. Further, alexithymia in PSP seems to be predicted by the presence of depression. Altered emotional capability could be related to specific neurophysiological dysfunction occurring precociously in PSP; therefore, its identification could orient the diagnosis toward PSP cases.

Anhedonia is associated with suicidal ideation independently of depression: A meta-analysis

BACKGROUND

Anhedonia is considered a suicide risk factor in patients with major affective disorders. Here, we wanted to quantify the association between anhedonia and current suicidal ideation according to the absence/presence of between-group differences for depressive scores and psychiatric disorders.

METHODS

We performed a meta-analysis of data on studies retrieved from Medline, Web of Science, and PsycINFO from 1965 to 2016 using, among others, the terms (suicid* or depression) and anhedonia.

RESULTS

We identified 15 observational case-control studies that investigated the anhedonia differences in individuals with and without current (i.e., within the past week, independently of the lifetime suicidality status) suicidal ideation (defined as thoughts of killing oneself). Overall, 657 subjects with and 6,690 subjects without current suicidal ideation could be compared. Anhedonia level was higher in the group with current suicidal ideation than in the group without, with a medium effect size (standardized mean difference = 0.57, z = 5.43, P < 0.001, 95% confidence interval, CI = 0.37-0.79). The association between anhedonia and current suicidal ideation remained significant when controlling for depression and psychiatric disorders. The anhedonia scales used in the selected studies did not allow investigating consummatory and motivational anhedonia separately.

CONCLUSION

Our major finding is the robust association between anhedonia and current suicidal ideation, independently of depression. This is highly relevant for the clinicians' daily practice and might help improving suicidal risk detection and the development of new therapeutic strategies for suicide prevention.

Cognitive Function in Parkinson's Disease Patients with and without Anxiety

Research on the implications of anxiety in Parkinson's disease (PD) has been neglected despite its prevalence in nearly 50% of patients and its negative impact on quality of life. Previous reports have noted that neuropsychiatric symptoms impair cognitive performance in PD patients; however, to date, no study has directly compared PD patients with and without anxiety to examine the impact of anxiety on cognitive impairments in PD. This study compared cognitive performance across 50 PD participants with and without anxiety (17 PDA+; 33 PDA−), who underwent neurological and neuropsychological assessment. Group performance was compared across the following cognitive domains: simple attention/visuomotor processing speed, executive function (e.g., set-shifting), working memory, language, and memory/new verbal learning. Results showed that PDA+ performed significantly worse on the Digit Span forward and backward test and Part B of the Trail Making Task (TMT-B) compared to the PDA− group. There were no group differences in verbal fluency, logical memory, or TMT-A performance. In conclusion, anxiety in PD has a measurable impact on working memory and attentional set-shifting.

Alexithymia in Parkinson's disease: A systematic review of the literature

INTRODUCTION

In this systematic review, we aimed to evaluate the role of alexithymia in Parkinson's disease (PD) and its relationship to neurological, neuropsychiatric, cognitive, and neuroimaging correlates.

METHODS

The database was selected using PubMed Services, Cochrane, PsycNET and Scopus and a number of key words. Further studies were sought by manually searching for secondary sources, including relevant journals and references in primary articles. The search was restricted to articles written in English between January 1980 and August 2015.

RESULTS

Ten studies reported that alexithymia prevalence was about double in PD patients compared to control subjects and that specific dimensions of alexithymia might be related to depression, anxiety, apathy and impulsivity. Some studies investigated the relationship between alexithymia and neuropsychological symptoms and found correlations with frontal and parietal lobe functions. Two studies on neurological features reported a link between alexithymia and disease stage or a specific motor subtype of PD; the remaining studies found that alexithymia was independent from neurological symptoms, dopaminergic therapy and laterality of motor symptom onset. Data on neuroimaging correlates and therapeutic intervention on alexithymia in PD patients are still lacking.

CONCLUSION

Although results suggest that alexithymia is a primary characteristics of PD, further studies with larger patient samples are needed to definitively clarify the impact of alexithymia on the clinical features of PD patients.

Hedonic deficits in Parkinson's disease: is consummatory anhedonia specific?

Background: Anhedonia, the lowered ability to experience pleasure, is one of the non-motor symptoms of Parkinson’s disease (PD) that is underdiagnosed and consequently undertreated. Few studies have investigated anhedonia in PD by taking into account the influence of socio-demographic variables and versus a control group composed of patients with a pure motor neurologic disease other than PD. The aim of this study was to investigate hedonic deficits in patients with PD compared to a control group of patients with non-Parkinson motor neurologic disease (OND), matched for age, gender, level of education, and inpatient/outpatient status. Distinctions between anticipatory and consummatory anhedonia and between endogenomorphic and non-endogenomorphic depression were taken into account.

Methods: The study population comprised 49 PD patients and 40 subjects with OND. Anhedonia was rated by using the anticipatory [Temporal Experience Pleasure Scale (TEPS)-ANT] and consummatory (TEPS-CONS) subscales of the TEPS and two subscales extracted from the revised Physical Anhedonia Scale (PAS), measuring physical anticipatory (PAS-ANT) and physical consummatory (PAS-CONS) anhedonias. The Snaith–Hamilton Pleasure Scale (SHAPS) and the Beck Depression Inventory-II (BDI-II) were also used together with a subscale extracted from the BDI-II (ENDO-BDI-II) for the diagnosis of endogenomorphic depression. Statistical analyses were performed on the whole group and on the PD group.

Results: As hypothesized, several anhedonia scores varied with age and gender in the whole population or in the PD group. On univariate or multivariate analyses, only PAS-CONS was specific for PD and only SHAPS scores differed between depression subtypes in the whole population or the PD group.

Conclusion: This study suggests that physical consummatory anhedonia could be specific to PD subjects.

Clinical correlates of anhedonia in patients with Parkinson's disease

OBJECTIVE

To investigate the prevalence and clinical correlates of anhedonia in patients with Parkinson's disease (PD) and to also examine the relationship between anhedonia and the QOL.

METHODS

One hundred and seventeen patients with PD completed the Snaith-Hamilton Pleasure Scale (SHAPS), the State-Trait Anxiety Inventory (STAI), the Beck Depression Inventory Second Edition (BDI-II), Starkstein's Apathy Scale (AS) and a quality of life (QOL) battery. Hoehn and Yahr (HY) staging, the Unified Parkinson's Disease Rating Scale (UPDRS) and the Mini-Mental State Examination (MMSE) were administered on the same day.

RESULTS

Anhedonia (SHAPS score≥3) was diagnosed in 15% of the patients. The SHAPS score was found to be significantly correlated with the HY stage and the UPDRS (I, IVB, IVC, total), BDI-II, AS and STAI (State, Trait) scores. A multivariate analysis revealed that the BDI-II and STAI (Trait) scores significantly influenced the SHAPS scores. The SHAPS scores were found to be negatively correlated with the QOL.

CONCLUSIONS

These findings indicate that anhedonia is associated with depression and anxiety. In addition, recognizing anhedonia in patients with PD is important since it may have a negative effect on the QOL.