Cerebral ventricle-brain ratio in monozygotic twins discordant and concordant for schizophrenia

Comprehensive treatment of dementia with Lewy bodies

Dementia with Lewy bodies is an under-recognized disease; it is responsible for up to 20 % of all dementia cases. Accurate diagnosis is essential because the management of dementia with Lewy bodies is more complex than many neurodegenerative diseases. This is because alpha-synuclein, the pathological protein responsible for dementia with Lewy bodies (and Parkinson's disease), produces symptoms in multiple domains. By dividing the symptoms into cognitive, neuropsychiatric, movement, autonomic, and sleep categories, a comprehensive treatment strategy can be achieved. Management decisions are complex, since the treatment of one set of symptoms can cause complications in other symptom domains. Nevertheless, a comprehensive treatment program can greatly improve the patient's quality of life, but does not alter the progression of disease. Cholinesterase inhibitors are effective for cognitive and neuropsychiatric symptoms; rivastigmine has the widest evidence base. Special care needs to be taken to avoid potentially fatal idiopathic reactions to neuroleptic medications; these should be used for short periods only when absolutely necessary and when alternative treatments have failed. Pimavanserin, a selective serotonin 5-HT2A inverse agonist, holds promise as an alternative therapy for synuclein-associated psychosis. Levodopa/carbidopa treatment of parkinsonism is often limited by dopa-induced exacerbations of neuropsychiatric and cognitive symptoms. Autonomic symptoms are under-recognized complications of synucleinopathy. Constipation, urinary symptoms and postural hypotension respond to standard medications. Rapid eye movement sleep behavior disorder is highly specific (98 %) to the synucleinopathies. Nonpharmacological treatments, melatonin and clonazepam are all effective.

The monoaminergic footprint of depression and psychosis in dementia with Lewy bodies compared to Alzheimer's disease

Introduction

Depression and psychosis are two of the most severe neuropsychiatric symptoms (NPS) in dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD). Both NPS have negative effects on cognitive performance and life expectancy. The current study aimed to investigate and compare monoaminergic etiologies between both neurodegenerative conditions, given the lack of an efficient pharmacological treatment until present.

Methods

Eleven behaviorally relevant brain regions of the left frozen hemisphere of 10 neuropathologically confirmed AD patients with/without depression (AD + D/-D; 5 were psychotic within AD + D), 10 confirmed DLB patients, all of whom were depressed (DLB + D; 5 psychotic patients), and, finally, 10 confirmed control subjects were regionally dissected. All patients were retrospectively assessed before death using the Behavioral Pathology in Alzheimer’s Disease Rating Scale (Behave-AD) and Cornell Scale for Depression in Dementia amongst others. The concentrations of dopamine (DA), serotonin (5-HT), (nor)adrenaline and respective metabolites, i.e. 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), 5-hydroxy-3-indoleacetic acid (5-HIAA), and, 3-methoxy-4-hydroxyphenylglycol (MHPG), were determined using reversed-phase high-performance liquid chromatography with electrochemical detection.

Results

DLB subjects had the overall lowest monoamine and metabolite concentrations regarding 33 out of 41 significant monoaminergic group alterations. Moreover, MHPG levels were significantly decreased in almost 8 out of 11 brain regions of DLB- compared to AD patients. We also observed the lowest 5-HT and 5-HIAA levels, and 5-HIAA/5-HT turnover ratios in DLB + D compared to AD + D subjects. Additionally, a 4- and 7-fold increase of DOPAC/DA and HVA/DA turnover ratios, and, a 10-fold decrease of thalamic DA levels in DLB + D compared to AD + D patients and control subjects was noticed. Regarding psychosis, hippocampal DA levels in the overall DLB group significantly correlated with Behave-AD AB scores. In the total AD group, DA levels and HVA/DA ratios in the amygdala significantly correlated with Behave-AD AB scores instead.

Conclusions

Monoaminergic neurotransmitter alterations contribute differently to the pathophysiology of depression and psychosis in DLB as opposed to AD, with a severely decreased serotonergic neurotransmission as the main monoaminergic etiology of depression in DLB. Similarly, psychosis in DLB might, in part, be etiologically explained by dopaminergic alterations in the hippocampus, whereas in AD, the amygdala might be involved.

Study factors influencing ventricular enlargement in schizophrenia: a 20 year follow-up meta-analysis

A meta-analysis was performed on studies employing the ventricular-brain ratio to compare schizophrenic subjects to that of normal controls. This was a follow-up to a similar meta-analysis published in 1992 in which study-, in addition to clinical-, factors were found to contribute significantly to the reported difference between patients with schizophrenia and controls. Seventy-two (N=72) total studies were identified from the peer reviewed literature, 39 from the original meta-analysis, and 33 additional studies published since which met strict criteria for inclusion and analysis - thus representing ~30 years of schizophrenia ventricular enlargement research. Sample characteristics from schizophrenics and controls were coded for use as predictor variables against within sample VBR values as well as for between sample VBR differences. Additionally, a number of factors concerning how the studies were conducted and reported were also coded. Obtained data was subjected to unweighted univariate as well as multiple regression analyses. In particular, results indicated significant differences between schizophrenics and controls in ventricular size but also the influence of the diagnostic criteria used to define schizophrenia on the magnitude of the reported VBR. This suggests that differing factors of the diagnostic criteria may be sensitive to ventricular enlargement and might be worthy of further examination. Interestingly, we observed an inverse relationship between VBR difference and the number of co-authors on the study. This latter finding suggests that larger research groups report smaller VBR differences and may be more conservative or exacting in their research methodology. Analyses weighted by sample size provided identical conclusions. The effects of study factors such as these are helpful for understanding the variation in the size of the reported differences in VBR between patients and controls as well as for understanding the evolution of research on complex clinical syndromes employing neuroimaging morphometrics.

A controlled study of brain structure in monozygotic twins concordant and discordant for schizophrenia

BACKGROUND

We examined monozygotic twins concordant and discordant for schizophrenia to clarify the role of genetic and environmental factors in determining brain abnormalities.

METHODS

Magnetic resonance imaging brain scans were obtained from 14 monozygotic twin pairs concordant and 10 monozygotic pairs discordant for schizophrenia, as well as 17 pairs of monozygotic control twins. Twenty-two discordant sibling-pairs and 56 pairs of unrelated control subjects were included to assess the extent of genetic control over these structures.

RESULTS

Within-pair similarities for whole brain volume increased as pair members were more closely related genetically (monozygotic twins > siblings > unrelated control subjects). Schizophrenic twins, whether from concordant or discordant pairs, had smaller whole brain volumes than control twins. The probands of discordant pairs showed more abnormalities in hippocampal, third and lateral ventricular volumes than concordant twins.

CONCLUSIONS

Whole brain volume is under high genetic control and smaller whole brain volume is a reflection of the genetic liability to develop schizophrenia. The variation in hippocampal and ventricular volumes within discordant monozygotic pairs indicates a role for environmental factors in determining these volume abnormalities in schizophrenia. Such factors may also underlie the more extensive morphometric deviations in patients from monozygotic discordant twins than in their counterparts from concordant twins.

Gray and white matter volume abnormalities in monozygotic and same-gender dizygotic twins discordant for schizophrenia

BACKGROUND

Whole brain tissue volume decreases in schizophrenia have been related to both genetic risk factors and disease-related (possibly nongenetic) factors; however, whether genetic and environmental risk factors in the brains of patients with schizophrenia are differentially reflected in gray or white matter volume change is not known.

METHODS

Magnetic resonance imaging (1.5 T) brain scans of 11 monozygotic and 11 same-gender dizygotic twin pairs discordant for schizophrenia were acquired and compared with 11 monozygotic and 11 same-gender dizygotic healthy control twin pairs.

RESULTS

Repeated-measures volume analysis of covariance revealed decreased whole brain volume in the patients with schizophrenia as compared with their co-twins and with healthy twin pairs. Decreased white matter volume was found in discordant twin pairs compared with healthy twin pairs, particularly in the monozygotic twin pairs. A decrease in gray matter was found in the patients compared with their co-twins and compared with the healthy twins.

CONCLUSIONS

The results suggest that the decreases in white matter volume reflect the increased genetic risk to develop schizophrenia, whereas the decreases in gray matter volume are related to environmental risk factors. Study of genes involved in the (maintenance) of white matter structures may be particularly fruitful in schizophrenia.