Frontal Dysfunction and Frontal Cortical Synapse Loss in Alcoholism –The Main Cause of Alcohol Dementia?
17 May 2001-Dementia and Geriatric Cognitive Disorders (Karger Publishers)-Vol. 12, Iss: 4, pp 289-294
TL;DR: A consistent pattern of synapse loss in the superior laminae of the frontal cortical area 10 of Brodman in heavy drinkers, not related to liver disease or possible previous mental disease, seems to be a plausible main cause of the alcoholic frontal symptomatology and alcoholic dementia.
Abstract: Alcoholics often develop personality and behavioural changes, social and personal neglect, confabulation, lack of insight, empathy and emotional control. Such symptoms would increase the risk of engagement in and exposure to acts of violence and criminal activities carrying a risk of physical damage including head trauma and violent death. This was the case in at least 4 of the studied cases. A structural basis for such frontal lobe symptoms was looked for in a forensic material of 18 alcoholics, compared with an age-matched control group with regard to liver disease, brain changes of the Wernicke-Korsakoff type and cortical, especially frontal cortical changes. The salient finding was a consistent pattern of synapse loss in the superior laminae of the frontal cortical area 10 of Brodman in heavy drinkers, not related to liver disease or possible previous mental disease. The synapse loss is more likely related to alcohol, possibly mediated through vitamin B deficiency. Brain stem lesions as a source of additional symptoms cannot be dismissed. This pattern of synapse loss in alcoholism has not been described previously. The cortical changes are closely similar to those found in frontotemporal dementia, and seem to be a plausible main cause of the alcoholic frontal symptomatology and alcoholic dementia.
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TL;DR: This review integrates recent physiological and molecular understanding of the role of podocytes during the maintenance and failure of the glomerular filtration barrier with hereditary nephrotic syndromes identified over the last 2 years.
Abstract: Glomerular podocytes are highly specialized cells with a complex cytoarchitecture. Their most prominent features are interdigitated foot processes with filtration slits in between. These are bridged by the slit diaphragm, which plays a major role in establishing the selective permeability of the glomerular filtration barrier. Injury to podocytes leads to proteinuria, a hallmark of most glomerular diseases. New technical approaches have led to a considerable increase in our understanding of podocyte biology including protein inventory, composition and arrangement of the cytoskeleton, receptor equipment, and signaling pathways involved in the control of ultrafiltration. Moreover, disturbances of podocyte architecture resulting in the retraction of foot processes and proteinuria appear to be a common theme in the progression of acquired glomerular disease. In hereditary nephrotic syndromes identified over the last 2 years, all mutated gene products were localized in podocytes. This review integrates our recent physiological and molecular understanding of the role of podocytes during the maintenance and failure of the glomerular filtration barrier.
1,358 citations
TL;DR: In the diseases studied, the decrease of slit diaphragm proteins was related to the effacement of foot processes and coincided with a rise of the levels of the corresponding mRNA transcripts, which suggests that the alterations in the expression of podocyte-associated molecules represent a compensatory reaction of the podocyte that results from damage associated with proteinuria.
Abstract: Proteinuria is a poorly understood feature of many acquired renal diseases. Recent studies concerning congenital nephrotic syndromes and findings in genetically modified mice have demonstrated that podocyte molecules make a pivotal contribution to the maintenance of the selective filtration barrier of the normal glomerulus. However, it is unclear what role podocyte molecules play in proteinuria of acquired renal diseases. This study investigated the mRNA and protein expression of several podocyte-associated molecules in acquired renal diseases. Forty-eight patients with various renal diseases were studied, including minimal change nephropathy, focal segmental glomerulosclerosis, IgA nephropathy, lupus nephritis, and diabetic nephropathy, together with 13 kidneys with normal glomerular function. Protein levels of nephrin, podocin, CD2-associated protein, and podocalyxin were investigated using quantitative immunohistochemical assays. Real-time PCR was used to determine the mRNA levels of nephrin, podocin, and podoplanin in microdissected glomeruli. The obtained molecular data were related to electron microscopic ultrastructural changes, in particular foot process width, and to clinical parameters. In most acquired renal diseases, except in IgA nephropathy, a marked reduction was observed at the protein levels of nephrin, podocin, and podocalyxin, whereas an increase of the glomerular mRNA levels of nephrin, podocin, and podoplanin was found, compared with controls. The mean width of the podocyte foot processes was inversely correlated with the protein levels of nephrin (r = -0.443, P < 0.05), whereas it was positively correlated with podoplanin mRNA levels (r = 0.468, P < 0.05) and proteinuria (r = 0.585, P = 0.001). In the diseases studied, the decrease of slit diaphragm proteins was related to the effacement of foot processes and coincided with a rise of the levels of the corresponding mRNA transcripts. This suggests that the alterations in the expression of podocyte-associated molecules represent a compensatory reaction of the podocyte that results from damage associated with proteinuria.
272 citations
TL;DR: It is suggested that brain activation in left frontal and right cerebellar regions that support the articulatory control system of verbal working memory may require a compensatory increase in alcoholics in order to maintain the same level of performance as controls.
213 citations
Cites result from "Frontal Dysfunction and Frontal Cor..."
...In vivo MRI evidence for regional tissue shrinkage is consistent with postmortem studies that have revealed neuronal loss in frontal lobes (Brun and Andersson, 2001; Courville, 1955; Harper and Kril, 1990; Kril et al., 1997; Kril and Harper, 1989) and reduction of soma size and processes in cerebellar vermis and hemispheres (Baker et al....
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TL;DR: Ethanol affects cognition in a number of ways and in sufficient dosage can cause lasting dementia, but in low-to-moderate dosage reduces the risk of dementia, including Alzheimer type.
Abstract: Ethanol affects cognition in a number of ways. Indirect effects include intoxication, withdrawal, brain trauma, central nervous system infection, hypoglycemia, hepatic failure, and Marchiafava-Bignami disease. Nutritional deficiency can cause pellagra and Wernicke-Korsakoff disorder. Additionally, ethanol is a direct neurotoxin and in sufficient dosage can cause lasting dementia. However, ethanol also has neuroprotectant properties and in low-to-moderate dosage reduces the risk of dementia, including Alzheimer type. In fetuses ethanol is teratogenic, and whether there exists a safe dose during pregnancy is uncertain and controversial.
190 citations
Cites result from "Frontal Dysfunction and Frontal Cor..."
...spectroscopy confirmed the special vulnerability of pre-frontal cortex in alcoholics, and abnormalities in planning, organization, problem solving, and abstracting, as well as lack of insight, disinhibition, and perseveration are consistent with these regional vulnerabilities [55-58]....
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TL;DR: The results indicate that reduced levels of proteins associated with foot processes and the glomerular slit diaphragm likely contribute, along with reduced Levels of GBM collagens, to the nephropathy associated with NPS.
Abstract: LMX1B encodes a LIM-homeodomain transcription factor. Mutations in LMX1B cause nail-patella syndrome (NPS), an autosomal dominant disease with skeletal abnormalities, nail hypoplasia, and nephropathy. Expression ofglomerular basement membrane (GBM) collagens is reduced in Lmx1b - / - mice, suggesting one basis for NPS nephropathy. Here, we show that Lmx1b - / - podocytes have reduced numbers of foot processes, are dysplastic, and lack typical slit diaphragms, indicating an arrest in development. Using antibodies to podocyte proteins important for podocyte function, we found that Lmx1b - / - podocytes express near-normal levels of nephrin, synaptopodin, ZO-1, α3 integrin, and GBM laminins. However, mRNA and protein levels for CD2AP and podocin were greatly reduced, suggesting a cooperative role for these molecules in foot process and slit diaphragm formation. We identified several LMX1B binding sites in the putative regulatory regions of both CD2AP and NPHS2 (podocin) and demonstrated that LMX1B binds to these sequences in vitro and can activate transcription through them in cotransfection assays. Thus, LMX1B regulates the expression of multiple podocyte genes critical for podocyte differentiation and function. Our results indicate that reduced levels of proteins associated with foot processes and the glomerular slit diaphragm likely contribute, along with reduced levels of GBM collagens, to the nephropathy associated with NPS.
156 citations
References
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TL;DR: Among 8735 autopsies performed during a 5-year period at Ulleval Hospital in Oslo, there were 70 cases of Wernicke's encephalopathy and 152 cases of alcoholic cerebellar atrophy.
369 citations
TL;DR: Dendritic and synaptic changes have been documented in uncomplicated alcoholics and these, together with receptor and transmitter changes, may explain functional changes and cognitive deficits that precede the more severe structural neuronal changes.
Abstract: The aim of this review is to identify neuropathological changes that are directly related to the long-term use of excessive amounts of alcohol (ethanol). There is still debate as to whether alcohol per se causes brain damage. The main problem has been to identify those lesions caused by alcohol itself and those caused by other common alcohol-related factors, principally thiamin deficiency. Careful selection and classification of alcoholic cases into those with and without these complications, together with detailed quantitative neuropathological analyses, has provided us with useful data. There is brain shrinkage in uncomplicated alcoholics which can largely be accounted for by loss of white matter. Some of this damage appears to be reversible. However, alcohol-related neuronal loss has been documented in specific regions of the cerebral cortex (superior frontal association cortex), hypothalamus (supraoptic and paraventricular nuclei), and cerebellum. The data is conflicting for several regions: the hippocampus, amygdala and locus ceruleus. No change is found in the basal ganglia, nucleus basalis, or serotonergic raphe nuclei. Many of the regions that are normal in uncomplicated alcoholics are damaged in those with the Wernicke-Korsakoff syndrome. Dendritic and synaptic changes have been documented in uncomplicated alcoholics and these, together with receptor and transmitter changes, may explain functional changes and cognitive deficits that precede the more severe structural neuronal changes. The pattern of damage appears to be somewhat different and species-specific in animal models of alcohol toxicity. Pathological changes that have been found to correlate with alcohol intake include white matter loss and neuronal loss in the hypothalamus and cerebellum.
359 citations
TL;DR: Although there was little evidence for relationships between performance on neuropsychological tests and volume of grey matter structures, significant correlations between some cognitive measures and subcortical and cortical fluid volumes were found.
Abstract: Twenty-eight chronic alcoholics and 36 age- and sex-matched non-alcoholic controls were examined with magnetic resonance imaging and brain morphometric analyses. Results confirmed large increases in subarachnoid cerebrospinal fluid (CSF) volume and mild ventricular enlargement in the alcoholics and revealed associated volume reductions of localized cortical and subcortical cerebral structures. Volume losses in the diencephalon, the caudate nucleus, dorsolateral frontal and parietal cortex, and mesial temporal lobe structures were the most prominent. Significant correlations between increments in cortical and ventricular CSF and decrements in the volume of cortical and subcortical grey matter were noted. Although there was little evidence for relationships between performance on neuropsychological tests and volume of grey matter structures, significant correlations between some cognitive measures and subcortical and cortical fluid volumes were found. The parallels between this pattern of affected structures and recent neuropathological findings are discussed.
334 citations
TL;DR: The results do not support the theory that chronic alcohol consumption is neurotoxic to hippocampal pyramidal neurons in humans and suggest that changes observed in rodent models of alcoholism do not parallel those observed in humans, questioning the validity of such models.
Abstract: High alcohol consumption for long periods of time causes significant hippocampal neurodegeneration in rodents. A single study using neuronal density measures has reported similar findings in humans. The present study aims to substantiate these findings in human alcoholics using unbiased stereological techniques. Both amnesic (n = 5) and nonamnesic (n = 7) chronic alcoholics were selected and compared with nonalcoholic controls (n = 8) and patients with marked memory loss and hippocampal neurodegeneration caused by Alzheimer's disease (n = 4). Hippocampal volume was significantly reduced in the alcoholics and in patients with Alzheimer's disease. However, in alcoholics the volume reduction occurred exclusively in the white matter, whereas both the gray and white matter were reduced in the patients with Alzheimer's disease. Neuron loss occurred exclusively from the CA1 and subiculum subregions of the hippocampus in Alzheimer's disease. No neuron loss occurred from any subregion of the hippocampus in alcoholics. There were no correlations with age and any of the volume or neuron number measures. Hippocampal volume correlated with brain volume and with the regional gray and white matter volumes within the hippocampus. In addition, hippocampal gray matter volume correlated with the number of CA1 pyramidal neurons. These results do not support the theory that chronic alcohol consumption is neurotoxic to hippocampal pyramidal neurons in humans. Further, the present results suggest that changes observed in rodent models of alcoholism do not parallel those observed in humans, questioning the validity of such models.
160 citations
TL;DR: The hypothesis of regional variations in the severity of cerebral cortical damage in alcoholism with shrinkage of neurons in most regions examined but neuronal loss only in the superior frontal gyrus is supported.
Abstract: Neuronal loss from the frontal superior cortex of the brains of alcoholics has recently been documented. In addition to this, a reduction in the mean neuronal area was also seen in the frontal and motor cortices. This suggested a regional specificity of neuronal damage in the brains of alcoholics. Further quantitation of other cortical regions of the same cases as used in the above study has been performed. The frontal cingulate and temporal cortices were examined and there was found to be no significant alteration in the number of neurons when compared to a control population. There was, however, a significant reduction in the mean size of the neuronal soma in the frontal cingulate cortex (P < 0.05). These data support the hypothesis of regional variations in the severity of cerebral cortical damage in alcoholism with shrinkage of neurons in most regions examined but neuronal loss only in the superior frontal gyrus.
144 citations