Phase synchronization of chlorophyll and total phosphorus oscillations as an indicator of the transformation of a lake ecosystem.

The ecosystem of the Naroch Lakes (Belarus) includes three water bodies, Lake Batorino, Lake Myastro and Lake Naroch. These lakes have a common catchment area. At the end of the 80 s, the ecosystem of the Naroch Lakes underwent a transformation, during which the nutrient load on the catchment area decreased, and the concentration of phosphorus as a limiting factor in these water bodies decreased significantly. At the same time, the Naroch Lakes were exposed to zebra mussel (Dreissena polymorpha Pallas) invasion. In the mid-90 s, the biological and hydrochemical characteristics of the ecosystem of the Naroch Lakes stabilized. We show here that complex processes associated with the transformation of the lake ecosystem and affecting both trophic interactions in the Naroch Lakes and the influence of environmental factors on them can be represented using a single parameter, the phase-locking index, PLI. In this case, a statistically significant numerical value of PLI characterizes the phase synchronization of two processes, oscillations of the concentration of total phosphorus, TP, and oscillations of the concentration of chlorophyll, Chl. We show that the phase synchronization of these processes occurs only after the stabilization of the ecosystem of the Naroch Lakes. In the period preceding the transformation of the lake ecosystem, there was no synchronization. Numerical evaluation of PLI as a holistic parameter allows us to characterize the transformation of the lake ecosystem as a whole without resorting to study of complex interactions of various factors involved in this transformation.

Health-related quality of life and its determinants in the urban Russian population with major depressive disorder: a cross-sectional study.

OBJECTIVE: Depressive disorders pose a major challenge to healthcare in the countries of the former Soviet Union. The objective of the current study was to evaluate health-related quality of life (HrQoL) and its determinants in outpatients with major depressive disorder in an urban Russian population. METHODS: We consecutively recruited 100 urban Russian outpatients with major depression and 100 non-depressed controls who were matched for age and sex. The severity of their depression was assessed using the Hamilton Depression Rating Scale (HDRS). HrQoL was evaluated using the EuroQol (the EQ-5D and the visual analogue scale, EQ VAS). Independent determinants of HrQoL were identified using multiple regression analysis. RESULTS: The mean EQ VAS score was 43.0 +/- 27.4 in patients with depression compared to 81.4 +/- 14.7 in the controls (p < 0.01). Out of the domains of the EQ-5D, "anxiety/depression," "usual activities," and "self-care" were the most impaired. Independent determinants of reduced HrQoL were: severity of depression according to the HDRS; violent suicide attempts; suicide attempts in the past; and drug addiction. CONCLUSIONS: HrQoL is considerably reduced in Russians with major depression. The disease-specific patterns of HrQoL impairment and the independent determinants of HrQoL identified in our study could be addressed in focused healthcare programs and clinical trials. Comorbid drug addiction as a determinant of HrQoL should receive greater attention in the management of depressive disorders in urban Russian populations.

Depression in elderly patients with Alzheimer dementia or vascular dementia and its influence on their quality of life.

BACKGROUND: Alzheimer dementia (AD) and vascular dementia (VD) are the most common causes of dementia in the elderly. Depression is an important co-morbid disorder in these diseases, which is often challenging to recognize. We investigated the prevalence of depression in patients with AD and VD and estimated the influence of depression on the health-related quality of life (HrQoL) in these patients. MATERIALS AND METHODS: We evaluated prevalence of depression in consecutively recruited patients with AD or VD (n= 98). Depression was diagnosed according to criteria of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) and scored using the Geriatric Depression Scale. The EuroQol (EQ-5D and visual analogue scale) was applied to evaluate HrQoL. The severity of cognitive impairment was measured by the Mini-Mental State Examination (MMSE). Multiple regression analysis was used to identify factors predicting severity of depression. RESULTS: The prevalence of depression in AD/VD was 87%. In comparison to the general population, HrQoL measured on the visual analogue scale was reduced by 54% in patients with AD/VD. In the dimension "anxiety/depression" of the EQ-5D, 81% of patients with AD/VD had moderate or severe problems. Depression showed significant association with reduced HrQoL (P<0.01). Independent predictors of more severe depression were older age, male gender, better MMSE scores and being not married. CONCLUSIONS: Depression is a prevalent psychiatric co-morbidity in patients with AD/VD, which is often under-diagnosed being masked by cognitive impairment. Depression is a predictor of reduced HrQoL in elder people with AD/VD. Therefore, they should be screened for presence of depressive symptoms and receive adequate antidepressant treatment.

Social and clinical determinants of quality of life in Parkinson's disease in a Russian cohort study.

Parkinson's disease (PD) is a chronic neurodegenerative disorder that has a major impact on health and longevity in Eastern countries. Studies investigating health-related quality of life (HRQoL) in Eastern European and Asian countries are scarce. The objective of this cross-sectional survey was to assess HRQoL in Russian patients with PD and identify its social and clinical determinants. The study included 100 outpatients with idiopathic PD and 100 controls. Patients were consecutively recruited from the neurological department of the Russian Medical State University in Moscow between October 2004 and December 2005. Regional healthy controls were matched for age and sex. The evaluation of HRQoL was performed using the EuroQol instrument (EQ-5D and EQ VAS). Disease severity was assessed using the Unified Parkinson's Disease Rating Scale (UPDRS). Multivariate regression analyses were used to identify independent determinants of HRQoL. HRQoL was more notably decreased in PD patients than in controls (98% versus 74% of individuals with moderate or severe problems in at least one dimension of the EQ-5D (p < 0.001), respectively). As compared to patients, the controls reported a higher mean EQ VAS score (74.0 +/- 16.0 versus 47.7 +/- 16.7, p < 0.001). Social and clinical determinants of HRQoL were age, disease severity, dystonia, depression, dementia and social support. While the HRQoL of patients with PD in Western countries is predominately affected by clinical parameters, social factors play an important role in Eastern countries. Our data should be considered in the development of national healthcare programs that seek to provide better social services support for patients with PD.