Depression in alpha-synucleinopathies: prevalence, pathophysiology and treatment

Peripheral Upregulation of Parkinson's Disease-Associated Genes Encoding α-Synuclein, β-Glucocerebrosidase, and Ceramide Glucosyltransferase in Major Depression

Due to the high comorbidity of Parkinson's disease (PD) with major depressive disorder (MDD) and the involvement of sphingolipids in both conditions, we investigated the peripheral expression levels of three primarily PD-associated genes: α-synuclein (SNCA), lysosomal enzyme β-glucocerebrosidase (GBA1), and UDP-glucose ceramide glucosyltransferase (UGCG) in a sex-balanced MDD cohort. Normalized gene expression was determined by quantitative PCR in patients suffering from MDD (unmedicated n = 63, medicated n = 66) and controls (remitted MDD n = 39, healthy subjects n = 61). We observed that expression levels of SNCA (p = 0.036), GBA1 (p = 0.014), and UGCG (p = 0.0002) were higher in currently depressed patients compared to controls and remitted patients, and expression of GBA1 and UGCG decreased in medicated patients during three weeks of therapy. Additionally, in subgroups, expression was positively correlated with the severity of depression and anxiety. Furthermore, we identified correlations between the gene expression levels and PD-related laboratory parameters. Our findings suggest that SNCA, GBA1, and UGCG analysis could be instrumental in the search for biomarkers of MDD and in understanding the overlapping pathological mechanisms underlying neuro-psychiatric diseases.

Neuronal haemoglobin induces loss of dopaminergic neurons in mouse Substantia nigra, cognitive deficits and cleavage of endogenous α-synuclein

Parkinson's disease (PD) presents the selective loss of A9 dopaminergic (DA) neurons of Substantia Nigra pars compacta (SNpc) and the presence of intracellular aggregates called Lewy bodies. α-synuclein (α-syn) species truncated at the carboxy-terminal (C-terminal) accumulate in pathological inclusions and promote α-syn aggregation and toxicity. Haemoglobin (Hb) is the major oxygen carrier protein in erythrocytes. In addition, Hb is expressed in A9 DA neurons where it influences mitochondrial activity. Hb overexpression increases cells' vulnerability in a neurochemical model of PD in vitro and forms cytoplasmic and nucleolar aggregates upon short-term overexpression in mouse SNpc. In this study, α and β-globin chains were co-expressed in DA cells of SNpc in vivo upon stereotaxic injections of an Adeno-Associated Virus isotype 9 (AAV9) and in DA iMN9D cells in vitro. Long-term Hb over-expression in SNpc induced the loss of about 50% of DA neurons, mild motor impairments, and deficits in recognition and spatial working memory. Hb triggered the formation of endogenous α-syn C-terminal truncated species. Similar α-syn fragments were found in vitro in DA iMN9D cells over-expressing α and β- globins when treated with pre-formed α-syn fibrils. Our study positions Hb as a relevant player in PD pathogenesis for its ability to trigger DA cells' loss in vivo and the formation of C-terminal α-syn fragments.

Depression in multiple system atrophy: Views on pathological, clinical and imaging aspects

Multiple system atrophy (MSA) is a common atypical parkinsonism, characterized by a varying combination of autonomic, cerebellar, and pyramidal systems. It has been noticed that the patients with MSA can be accompanied by some neuropsychiatric disorders, in particular depression. However, there is limited understanding of MSA-related depression. To bridge existing gaps, we summarized research progress on this topic and provided a new perspective regarding pathological, clinical, and imaging aspects. Firstly, we synthesized corresponding studies in order to investigate the relationship between depression and MSA from a pathological perspective. And then, from a clinical perspective, we focused on the prevalence of depression in MS patients and the comparison with other populations. Furthermore, the associations between depression and some clinical characteristics, such as life quality and gender, have been reported. The available neuroimaging studies were too sparse to draw conclusions about the radiological aspect of depression in MSA patients but we still described them in the presence of paper. Finally, we discussed some limitations and shortcomings existing in the included studies, which call for more high-quality basic research and clinical research in this field.

Late-Onset OCD as a Potential Harbinger of Dementia With Lewy Bodies: A Report of Two Cases

OBJECTIVES

Obsessive-compulsive disorder usually begins in adolescence or young adulthood. OCD cases appearing after the age of 50 years are rare, most often associated with inflammatory, brain lesions, or neurodegenerative comorbidities. We describe two cases of late-onset obsessive compulsive disorder followed by the development of Dementia with Lewy Bodies and review the links between these two disorders.

METHODS AND RESULTS

We describe the clinical history of two patients that first showed OCD symptoms at an atypical age (>60 years). After several failed treatment attempts, they were hospitalized in our unit. Both presented severe sensitivity to antipsychotic agents that led to a diagnosis of Dementia with Lewy Bodies. Administration of cholinesterase inhibitors was associated with decrease of psychiatric symptoms in both cases. In addition to those clinical observations, a systematic review of the literature suggests that, beyond prefrontal cortex, temporal lobe and putamen have important roles in OCD pathophysiology. Based on these findings, we discuss four hypotheses to explain the sequential appearance of OCD and DLB symptoms. First, we considered the possibility that comorbidity of OCD with DLB was coincidental. Second, we propose to interpret OCD symptoms as motor stereotypies. Third, we hypothesize that late-onset OCD might be a symptom of late-onset depression. Four, we hypothesize that through early deterioration of basal ganglia, DLB caused the onset of OCD.

CONCLUSION

In conclusion, we recommend that cases of late-onset treatment-resistant OCD should be carefully tested for possible organic etiologies, and for DLB in particular.

Alpha-Synuclein RNA Expression is Increased in Major Depression

Alpha-synuclein (SNCA) is a small membrane protein that plays an important role in neuro-psychiatric diseases. It is best known for its abnormal subcellular aggregation in Lewy bodies that serves as a hallmark of Parkinson’s disease (PD). Due to the high comorbidity of PD with depression, we investigated the role of SNCA in patients suffering from major depressive disorder (MDD). SNCA mRNA expression levels were analyzed in peripheral blood cells of MDD patients and a healthy control group. SNCA mRNA expression was positively correlated with severity of depression as indicated by psychometric assessment. We found a significant increase in SNCA mRNA expression levels in severely depressed patients compared with controls. Thus, SNCA analysis could be a helpful target in the search for biomarkers of MDD.

Motor and Nonmotor Symptoms of Parkinson's Disease: Antagonistic Pleiotropy Phenomena Derived from α-Synuclein Evolvability?

Lewy body diseases, such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), are associated with a wide range of nonmotor symptoms (NMS), including cognitive impairment, depression and anxiety, sleep disorders, gastrointestinal symptoms, and autonomic failure. The reason why such diverse and disabling NMS have not been weeded out but have persisted across evolution is unknown. As such, one possibility would be that the NMS might be somehow beneficial during development and/or reproductive stages, a possibility consistent with our recent view as to the evolvability of amyloidogenic proteins (APs) such as α-synuclein (αS) and amyloid-β (Aβ) in the brain. Based on the heterogeneity of protofibrillar AP forms in terms of structure and cytotoxicity, we recently proposed that APs might act as vehicles to deliver information regarding diverse internal and environmental stressors. Also, we defined evolvability to be an epigenetic phenomenon whereby APs are transgenerationally transmitted from parents to offspring to cope with future brain stressors in the offspring, likely benefitting the offspring. In this context, the main objective is to discuss whether NMS might be relevant to evolvability. According to this view, information regarding NMS may be transgenerationally transmitted by heterogeneous APs to offspring, preventing or attenuating the stresses related to such symptoms. On the other hand, NMS associated with Lewy body pathology might manifest through an aging-associated antagonistic pleiotropy mechanism. Given that NMS are not only specific to Lewy body diseases but also displayed in other disorders, including amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD), these conditions might share common mechanisms related to evolvability. This might give insight into novel therapy strategies based on antagonistic pleiotropy rather than on individual NMS from which to develop disease-modifying therapies.

Depressive Symptoms are Frequent in Atypical Parkinsonian Disorders

OBJECTIVE

To compare the incidence and prevalence of depressive symptoms in atypical parkinsonian (APD) syndromes versus Parkinson disease (PD).

METHODS

In a large retrospective patient cohort we analyzed the incidence and prevalence of depressive symptoms using the Beck Depression Inventory (BDI) and evaluated subjects longitudinally on subsequent visits. For individuals who followed in subsequent visits we calculated incidence rates in person-years as a measure of incidence.

RESULTS

We identified 361 patients with APD including Progressive Supranuclear Palsy (PSP), Corticobasal Degeneration (CBD), Multiple System Atrophy (MSA) and Dementia with Lewy Bodies (DLB), and 2352 PD controls. The mean BDI values were significantly higher in APD (F=14.19, p < 0.001). A significantly higher proportion of APD subjects screened positive for depressive symptoms both at initial and subsequent patient visits (p < 0.001), which appeared to be more severe in the APD subgroups. UPDRS part III and disease duration weakly correlated with depressive symptoms.

CONCLUSIONS

Our results suggest that the incidence and prevalence of depressive symptoms are higher in APD and appear also to be more severe than in PD. Depressive symptoms in APD are common and affect patients regardless of disease duration or motor severity.

NACP-Rep1 relates to Beck Depression Inventory scores in healthy humans

Alpha-synuclein (SNCA) is associated with a range of psychiatric diseases including neurodegeneration, alcohol craving, and depression. It regulates cellular homeostasis by virtue of its ability to interfere in dopaminergic, serotonergic, and noradrenergic pathways. To date, it is unclear whether the previously described association between SNCA and depressive symptomatology is limited to females with eating disorders or whether it could be extended to include healthy individuals. We included 105 women and 108 men. Genetic data and mRNA expression analyses were drawn from peripheral blood and the severity of depressive symptoms was quantified by the Beck's Depression Inventory (BDI). We found a significant association between the NACP-Rep1 length polymorphism and the BDI score (p = 0.004). Moreover, there was a significant gender dimorphism regarding mRNA expression of SNCA (p = 0.011). Our analysis revealed no further association between the In4 polymorphism or between the mRNA expression of SNCA and the BDI score. Since this investigation was limited to healthy individuals, conclusions concerning depression according to ICD-10 or DSM-IV cannot be drawn. The reported results may contribute to a better understanding of the molecular mechanisms linked to depressive symptoms.

Inhibitors of alpha-synuclein oligomerization and toxicity: a future therapeutic strategy for Parkinson's disease and related disorders

An abundance of genetic, histopathological, and biochemical evidence has implicated the neuronal protein, alpha-synuclein (alpha-syn) as a key player in the development of several neurodegenerative diseases, the so-called synucleinopathies, of which Parkinson's disease (PD) is the most prevalent. Development of disease appears to be linked to events that increase the intracellular concentration of alpha-syn or cause its chemical modification, either of which can accelerate the rate at which it forms aggregates. Examples of such events include increased copy number of genes, decreased rate of degradation via the proteasome or other proteases, or altered forms of alpha-syn, such as truncations, missense mutations, or chemical modifications by oxidative reactions. Aggregated forms of the protein, especially newly formed soluble aggregates, are toxic to cells, so that one therapeutic strategy would be to reduce the rate at which such oligomerization occurs. We have therefore designed several peptides and also identified small molecules that can inhibit alpha-syn oligomerization and toxicity in vitro. These compounds could serve as lead compounds for the design of new drugs for the treatment of PD and related disorders in the future.