Possible role of nerve growth factor in the pathogenesis of alcohol dependence

Alterations in Neurotrophins in Alcohol-Addicted Patients during Alcohol Withdrawal

BACKGROUND

Alcohol use disorder (AUD) is related to mental and somatic disorders that result in alcohol withdrawal syndrome (AWS), with 30% of AWS cases leading to life-threatening delirium tremens (DTs). Currently, studies do not support using any one biomarker in DTs. Neurotrophins affect neuromodulation, playing a role in the pathogenesis of AUD, AWS, and DTs.

METHODS

This review aims to summarize experimental and clinical data related to neurotrophins and S100B in neuroplasticity, as well as neurodegeneration in the context of AUD, AWS, and DTs. This work used publications that were selected based on the protocol consistent with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement.

RESULTS

The BDNF level could be a good candidate biomarker for relapse susceptibility, as it is significantly reduced during consumption and gradually increases during abstinence. GDNF influences AUD through its integral role in the function of dopaminergic neurons and ablates the return to alcohol-drinking behavior. NGF protects neurons from ethanol-induced cytotoxic damage and affects recovery from cognitive deficits after brain damage. The NT-3 level is decreased after alcohol exposure and is involved in compensatory mechanisms for cognitive decline in AUD. NT-4 affects oxidative stress, which is associated with chronic alcohol consumption. S100B is used as a biomarker of brain damage, with elevated levels in serum in AUD, and can protect 5-HT neurons from the damage caused by alcohol.

CONCLUSIONS

BDNF, GDNF, NT-3, NT-4, NGF, and S100B may be valuable markers for withdrawal syndrome. In particular, the most relevant is their association with the development of delirium complications. However, there are few data concerning some neurotrophins in AWS and DTs, suggesting the need for further research.

Decreased plasma concentrations of BDNF and IGF-1 in abstinent patients with alcohol use disorders

The identification of growth factors as potential biomarkers in alcohol addiction may help to understand underlying mechanisms associated with the pathogenesis of alcohol use disorders (AUDs). Previous studies have linked growth factors to neural plasticity in neurocognitive impairment and mental disorders. In order to further clarify the impact of chronic alcohol consumption on circulating growth factors, a cross-sectional study was performed in abstinent AUD patients (alcohol group, N = 91) and healthy control subjects (control group, N = 55) to examine plasma concentrations of brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1) and IGF-1 binding protein-3 (IGFBP-3). The association of these plasma peptides with relevant AUD-related variables and psychiatric comorbidity was explored. The alcohol group was diagnosed with severe AUD and showed an average of 13 years of problematic use and 10 months of abstinence at the moment of participating in the study. Regarding common medical conditions associated with AUD, we observed an elevated incidence of alcohol-induced liver and pancreas diseases (18.7%) and psychiatric comorbidity (76.9%). Thus, AUD patients displayed a high prevalence of dual diagnosis (39.3%) [mainly depression (19.9%)] and comorbid substance use disorders (40.7%). Plasma BDNF and IGF-1 concentrations were significantly lower in the alcohol group than in the control group (p<0.001). Remarkably, there was a negative association between IGF-1 concentrations and age in the control group (r = -0.52, p<0.001) that was not found in the alcohol group. Concerning AUD-related variables, AUD patients with liver and pancreas diseases showed even lower concentrations of BDNF (p<0.05). In contrast, the changes in plasma concentrations of these peptides were not associated with abstinence, problematic use, AUD severity or lifetime psychiatric comorbidity. These results suggest that further research is necessary to elucidate the role of BDNF in alcohol-induced toxicity and the biological significance of the lack of correlation between age and plasma IGF-1 levels in abstinent AUD patients.

Region-specific expression of precursor and mature brain-derived neurotrophic factors after chronic alcohol exposure

BACKGROUND

Alcohol abuse is a serious health problem worldwide that causes a variety of physical and mental disorders. Research has shown that the brain-derived neurotrophic factor (BDNF) plays an important role in alcohol addiction. The BDNF precursor (proBDNF) exhibits different actions than BDNF through separate receptors and pathways in the central nervous system. However, the effects of proBDNF and BDNF in alcohol addiction are not fully known.

OBJECTIVES

The objective was to identify the expression patterns and effects of proBDNF and BDNF after chronic alcohol exposure.

METHODS

A total of 40 male adult mice were studied. A mouse psychomotor sensitization (PS) model was established to explore the effects of BDNF and proBDNF treatment following chronic alcohol exposure. Reverse transcription PCR (RT-PCR) was performed to measure mRNA levels for BDNF, TrkB, P75NTR, and sortilin in the prefrontal cortex, hippocampus, and dorsal striatum of Kunming mice after chronic alcohol exposure.

RESULTS

In Kunming mice, chronic alcohol exposure up-regulated BDNF and TrkB mRNA levels in the prefrontal cortex, but decreased sortilin and P75 mRNA levels in the dorsal striatum. No changes in mRNA levels were found in other measured brain regions in the alcohol and control groups.

CONCLUSION

Chronic alcohol exposure induced the region-specific expression of BDNF and proBDNF and their respective receptors in the brain. These results suggest that BDNF and proBDNF signaling pathways may play major roles in alcohol preference and addiction.

Nerve Growth Factor Protects Against Alcohol-Induced Neurotoxicity in PC12 Cells via PI3K/Akt/mTOR Pathway

AIMS

To study whether autophagy participates in the neuroprotective effect of nerve growth factor (NGF) on neurons treated with alcohol.

METHODS

The autophagy-related markers were used to explore the role of autophagy in PC12 cells exposed to alcohol or pre-incubated with NGF before initiating the treatment with alcohol (100 mM; 6 h). PC12 cells were pre-incubated with 3-methyladenine (3-MA) (10 mM; 1 h) or rapamycin (100 nM; 1 h) before co-incubated with alcohol (100 mM; 6 h) in order to investigate the relationship between apoptosis and autophagy. PC12 cells were pre-incubated with LY294002 (50 μM; 30 min) before co-incubated with NGF and alcohol in order to analyze the protein expression of PI3K/Akt/mTOR pathway via western blotting.

RESULT

By methylthiazoltetrazolium, western blotting and flow cytometry assays, we found that cell viability decreased in a dose- and time-dependent manner after treatment with alcohol in PC12 cells. As cells were exposed to alcohol, the levels of LC3-II proteins became elevated, likewise, pre-treatment with 3-methyladenine (3-MA, an autophagic inhibitor) or rapamycin (an autophagic inducer) resulted in an increased or decreased percentage of apoptosis in contrast to other alcohol-treated groups, respectively. NGF markedly increased LC3-II production after treatment with alcohol in a dose-dependent manner. Moreover, NGF remarkably attenuated the phosphorylation effect of alcohol exposure on PI3K/Akt/mTOR pathway, which was suppressed by LY294002 (Akt inhibitor).

CONCLUSIONS

NGF protects against alcohol-induced neurotoxicity via PI3K/Akt/mTOR pathway.

SHORT SUMMARY

In this study, we chose the PC12 cell line as a neuronal model, and our results demonstrate that nerve growth factor can induce autophagy with the neuroprotective effect and regulatory mechanisms of alcohol-induced autophagy in PC12 cells.

Increased serum neurotrophin levels related to alcohol use disorder in a young population sample

BACKGROUND

The diagnosis of alcohol use disorder is based on clinical signs and on the measurement of biological markers. However, these markers are neither sufficiently sensitive, nor specific enough, for determining the effects of alcohol abuse on the central nervous system. Serum neurotrophins are important regulators of neural survival, development, function, and plasticity and have been found to be reduced in alcohol use disorder. The aim of this study was to investigate the alterations in serum neurotrophin levels (brain-derived neurotrophic factor [BDNF], glial-derived neurotrophic factor [GDNF], and nerve growth factor [NGF]) in alcohol use disorder in a young population, and thus possibly representing the early stages of the illness.

METHODS

This is a cross-sectional study, nested in a population-based study of people aged 18 to 35, involving 795 participants. The participants responded to the CAGE questionnaire, and a CAGE score of ≥2 was considered to be a positive screen for the abuse/dependence or moderate to severe alcohol use disorder. Serum BDNF, GDNF, and NGF levels were measured by ELISA.

RESULTS

In the CAGE ≥ 2 group, GDNF (p ≤ 0.001) and NGF (p ≤ 0.001) serum levels were significantly increased, and the BDNF elevation was near a statistical significance (p = 0.068) when compared to the CAGE < 2 group. A significantly positive correlation was observed only in the CAGE ≥ 2 group for BDNF/GDNF (r = 0.37, p < 0.001) and GDNF/NGF (r = 0.84, p < 0.001) levels. The correlation between the NGF and BDNF levels was significantly positive in both groups (r = 0.28, p < 0.001 for the CAGE < 2 group, and r = 0.30, p = 0.008 for the CAGE ≥ 2 group).

CONCLUSIONS

These results suggest that elevated neurotrophins are candidate markers for the early stages of alcohol misuse.

Serum Levels of Growth Factors in Alcohol-dependent Patients according to Comorbid Depressive Symptoms

OBJECTIVE

This study aims to reveal the relationship of depression with growth factors such as brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and insulin-like growth factor-1 (IGF-1) in inpatients diagnosed with alcohol dependence, and to identify candidate growth factors as biological markers to indicate the comorbid of alcohol dependence and depression.

METHODS

This study examined demographic factors in 45 alcohol-dependent patients. The ADS (Korean version of the Alcohol Dependence Scale) and BDI (Korean version of Beck's Depression Inventory) were used. BDNF, NGF, and IGF-1 were measured through ELISA.

RESULTS

The average drinking quantity and the ADS score were significantly more severe in alcohol-dependent patients with depression than in those without depression. Linearly comparing BDNF, NGF, and IGF-1 with BDI values, IGF-1 was the growth factor significantly correlated with BDI scores. BDI scores were significantly correlated with ADS scores. IGF-1 was significantly higher in alcohol-dependent patients with depression. Alcohol-dependent patients with depression had greater alcohol use and more severe ADS scores. BDNF and NGF showed no significant difference between alcohol-dependent patients with and without depression, but IGF-1 was significantly higher in those with than in those without depression.

CONCLUSION

IGF-1 was found to be associated with depression in alcohol-dependent patients, suggesting that IGF-1 in alcohol- dependent patients could be an important biomarker to indicate whether alcohol-dependence is accompanied by depression.

Changes in expression of BDNF and its receptors TrkB and p75NTR in the hippocampus of a dog model of chronic alcoholism and abstinence

Chronic ethanol consumption can produce learning and memory deficits. Brain-derived neurotrophic factor (BDNF) and its receptors affect the pathogenesis of alcoholism. In this study, we examined the expression of BDNF, tropomyosin receptor kinase B (TrkB) and p75 neurotrophin receptor (p75NTR) in the hippocampus of a dog model of chronic alcoholism and abstinence. Twenty domestic dogs (9-10 months old, 15-20 kg; 10 males and 10 females) were obtained from Harbin Medical University. A stable alcoholism model was established through ad libitum feeding, and anti-alcohol drug treatment (Zhong Yao Jie Jiu Ling, the main ingredient was the stems of watermelon; developed in our laboratory), at low- and high-doses, was carried out. The Zhong Yao Jie Jiu Ling was effective for the alcoholism in dogs. The morphology of hippocampal neurons was evaluated using hematoxylin-eosin staining. The number and morphological features of BDNF, TrkB and p75NTR-positive neurons in the dentate gyrus (DG), and the CA1, CA3 and CA4 regions of the hippocampus were observed using immunohistochemistry. One-way ANOVA was used to determine differences in BDNF, TrkB and p75NTR expression. BDNF, TrkB and p75NTR-positive cells were mainly localized in the granular cell layer of the DG and in the pyramidal cell layer of the CA1, CA3 and CA4 regions (DG>CA1>CA3>CA4). Expression levels of both BDNF and TrkB were decreased in chronic alcoholism, and increased after abstinence. The CA4 region appeared to show the greatest differences. Changes in p75NTR expression were the opposite of those of BDNF and TrkB, with the greatest differences observed in the DG and CA4 regions.

Association between insulin-like growth factor-1 and cognitive functions in alcohol-dependent patients

Studies in alcohol-dependent patients show that cognitive function can be influenced by chronic use of alcohol. Alcohol is a known neurotoxin that induces neurodegeneration in the brain. Although there are various causes of cognitive deficiency in alcohol-dependent patients, in this study we focus on the role of corticosteroids. The hypothalamus-pituitary-adrenal system (i.e., the HPA axis) plays a part in the control of corticosteroids. Recent studies show that insulin-like growth factor-1 (IGF-1) reflects the status of growth hormones under the action of the HPA axis. Therefore, IGF-1 is a potential indicator that reflects activity of the HPA axis, and a biomarker that may reflect the decline of cognitive function associated with alcohol-induced hypercortisolism. The purposes of this study are to identify an association between cognitive function and IGF-1, and to investigate IGF as the biological marker of cognitive decline in alcohol-dependent patients. Forty alcohol-dependent patients were selected as the subjects of this study. IGF-1 was measured through an enzyme-linked immunosorbent assay (ELISA). Clinical features were examined using the Korean version of the alcohol dependence scale (ADS-K). Cognitive functions were measured using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Comparative analysis was utilized to identify an association between CERAD measurement items and IGF-1. Alcohol-dependent patients demonstrated stable performance of most of the CERAD measures. Among the measures of the CERAD, only trail making test A showed a correlation to IGF-1. Compared to trail making test B, trail making test A is assumed to reflect basic cognitive functions including psychomotor speed, visual search and sequencing in alcohol-dependent patients, regardless of demographic characteristics such as the level of education of patients. Therefore, IGF-1 seems to play an important role in detecting the decline of basic cognitive functions in alcohol-dependent patients.

Decreased serum level of NGF in alcohol-dependent patients with declined executive function

The role of neurotrophic factors has been highlighted as a cause of decline in the cognitive function of alcohol-dependent patients. It is known that nerve-growth factor (NGF), one of the neurotrophins, is related to the growth and differentiation of nerve cells, as well as to a decline in cognitive function. The purpose of this study was to investigate the relationship between decreased NGF levels and cognitive decline in alcohol-dependent patients. The serum concentration of NGF was measured in 38 patients with chronic alcohol dependence, and several neuropsychological tests were also performed for cognitive function assessment. The results indicated a significant correlation between serum NGF level and the trail-making test part B, which evaluates executive function, but did not show a significant correlation with other cognitive function tests. An increased serum level of NGF was associated with a decreased completion time in the trail-making test B, and this finding indicates that a high serum level of NGF is related to greater executive function. This finding may imply a protective role of NGF in preventing neuron damage among patients with alcohol dependence. Larger controlled studies will be necessary in the future to investigate this issue further.

Chronic alcohol consumption, type 2 diabetes mellitus, insulin-like growth factor-I (IGF-I), and growth hormone (GH) in ethanol-treated diabetic rats

AIMS

Alcohol has deleterious influences on glucose metabolism which may contribute to the development of type 2 diabetes mellitus (T2DM). Insulin-like growth factor I (IGF-I) and growth hormone (GH), which interact with insulin to modulate metabolic control, have been shown to be related to impaired glucose tolerance. This study was conducted to assess the possibility that altered circulating IGF-I and GH levels contribute to the exacerbation of T2DM by alcohol use in type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats and non-diabetic Long-Evans Tokushima Otsuka (LETO) rats.

MAIN METHOD

OLETF rats were pair-fed a Lieber-DeCarli Regular Ethanol diet and LETO rats were pair-fed a control diet for 6 weeks. At 6 weeks, an Intraperitoneal Glucose Tolerance Test (IP-GTT) was performed and IGF-I and GH levels were evaluated.

KEY FINDINGS

Prior to an IP-GTT, OLETF-Ethanol (O-E) group had significantly a decrease in the mean glucose levels compared to OLETF-Control (O-C) group. At 120 min post IP-GTT, the O-E group had significantly an increase in the mean glucose levels compared to O-C group. The serum IGF-I levels were significantly lower and the serum GH levels were significantly higher in the O-E group than in L-C group.

SIGNIFICANCE

These results suggest that IGF-I and GH are prominent in defining the risk and development of T2DM, and may be adversely affected by heavy alcohol use, possibly mediating its diabetogenic effects. Thus, the overall glucose intolerance in the setting of alcoholism may be attributable to inappropriate alteration of IGF-I and GH levels.

Serum brain-derived neurotrophic factor and nerve growth factor concentrations change after alcohol withdrawal: preliminary data of a case-control comparison

BACKGROUND

Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are involved in neuroadaptation and foster survival of central and peripheral neurons. In this study, we addressed the question whether BDNF and NGF serum concentrations change during subacute alcohol withdrawal in patients with alcohol dependence compared to healthy controls.

METHODS

Fifteen patients (age 48.6 ± 7 years) and 15 healthy age-matched controls (age 48.8 ± 7 years) participated consecutively in a 2-week withdrawal study.

RESULTS

Mean BDNF levels (7.8 ng/ml, IQR = 4.4-10.7 vs. 16.5 ng/ml, IQR = 13.9-25.6; Z = -3.8, p < 0.0001) and NGF levels (5.8 pg/ml, IQR = 3.8-13.0 vs. 18.4 pg/ml, IQR = 10.9-25.1; Z = -2.5, p = 0.012) were significantly decreased in alcohol-dependent subjects when compared to healthy matched controls. NGF concentrations decreased significantly from day 3 to day 14 (Z = -2.36; p = 0.019). Mean BDNF concentrations showed a tendency to increase after withdrawal from day 3 to day 14 (Z = 1.7; p = 0.078).

CONCLUSION

Decreased NGF and BDNF concentrations in patients suffering from alcohol dependence, which stabilize after physical withdrawal, are in line with withdrawal symptoms and neurological risk factors. In turn, increase of BDNF after acute withdrawal might be connected to neurobiological and behavioral stabilization.

Effects of nerve growth factor (NGF), fluoxetine, and amitriptyline on gene expression profiles in rat brain

Evidence suggests that nerve growth factor (NGF) may have antidepressant properties but the pharmacological mechanisms remain unknown. Previously, we found that NGF improved performance in the forced swim test in Flinders Sensitive Line rats, but did not appear to have similar biochemical actions with the antidepressant fluoxetine. Gene expression profiles for neurotransmitter receptors and regulator-related genes in the amygdala/hippocampus were determined in rats treated for 14days with NGF, fluoxetine, amitriptyline, or saline. Gene expression was measured using an RT(2) profiler PCR Array System to determine the basis for this effect. Compared with saline, there were numerous genes with significantly altered mRNA levels in the amygdala/hippocampal region. Overlap was found between the mRNA levels of genes altered by NGF and the two antidepressant medications including genes related to the cholinergic and dopaminergic systems. However, decreased mRNA levels of Drd5, Sstr3, Htr3a, and Cckar genes in the amygdala/hippocampus were uniquely regulated by NGF. The results of this study are consistent with a previous conclusion that the antidepressant effects of NGF are mediated through non-traditional receptors for traditionally considered neurotransmitters and may suggest a particular utility of NGF in treating comorbid depression and addiction.

The brain-derived neurotrophic factor is associated with alcohol dependence-related depression and antidepressant response

Brain-derived neurotrophic factor (BDNF) plays an essential role in neuronal survival, proliferation, and synaptic remodeling and modulates the function of many other neurotransmitters. Additionally, it likely underlies neurodegenerative and psychiatric disorders, including alcohol dependence-related depression (AD-D). Here, we investigated the possible association between three single nucleotide polymorphisms (SNPs) of the BDNF gene (rs13306221, rs6265, rs16917204) and AD-D. Of 548 patients with alcohol dependence (AD), 166 had AD-D and 312 healthy controls. Response to 8-week sertraline treatment was also assessed. The frequency of the A allele of rs6265 (Val66Met) was significantly higher in AD-D patients than in the healthy controls (p=0.009 after Bonferroni correction). The analysis revealed a strong association between the rs6265 genotype distribution and AD-D (p=0.005 after Bonferroni correction), and the A allele of rs6265 was significantly overrepresented in AD-D patients compared to AD without depression (AD-nD) patients (p=0.001 after Bonferroni correction). Additionally, carriers of the A allele of rs6265 responded better to sertraline treatment (p=0.001). Our results suggested a novel association between BDNF rs6265 and AD-D. These findings might lead to earlier detection of AD-D, perhaps providing better tools for clinical care of these patients in the future.

Nerve growth factor β polypeptide (NGFB) genetic variability: association with the methadone dose required for effective maintenance treatment

Opioid addiction is a chronic disease with high genetic contribution and a large inter-individual variability in therapeutic response. The goal of this study was to identify pharmacodynamic factors that modulate methadone dose requirement. The neurotrophin family is involved in neural plasticity, learning, memory and behavior and deregulated neural plasticity may underlie the pathophysiology of drug addiction. Brain-derived neurotrophic factor (BDNF) was shown to affect the response to methadone maintenance treatment. This study explores the effects of polymorphisms in the nerve growth factor (β polypeptide) gene, NGFB, on the methadone doses required for successful maintenance treatment for heroin addiction. Genotypes of 14 NGFB polymorphisms were analyzed for association with the stabilizing methadone dose in 72 former severe heroin addicts with no major co-medications. There was significant difference in methadone doses required by subjects with different genotypes of the NGFB intronic single-nucleotide polymorphism rs2239622 (P=0.0002). These results may have clinical importance.

Role of neurotrophic factors in behavioral processes: implications for the treatment of psychiatric and neurodegenerative disorders

Neurotrophins are important regulators of neuronal function in the developing and adult brain and thus play a critical role in sustaining normal behavioral function. Brain-derived neurotrophic factor (BDNF) has been the most widely studied neurotrophin because of its important role as modulator of synaptic plasticity, which is essential to the regulation of experience-dependent behavior. Extensive work implicates BDNF in hippocampus-dependent forms of learning and memory, although it also regulates other cognitive processes. A role for BDNF in anxiety-related disorders and aggressive behavior can also be suspected. More importantly, BDNF signaling has recently emerged as a key player in the development of drug addiction and is well known to be involved in adaptation to stress and stress-related disorders. NGF in the other hand is thought to be involved in aggression and alcohol dependence. Finally, BDNF appears to participate in the therapeutic effects of drugs and interventions capable of reversing or attenuating behavioral disturbances relevant to psychiatric and neurodegenerative disorders. Compounds mimicking BDNF signaling, however, are unlikely to be used in a clinical context, given their adverse side effects and pharmacokinetic limitations.

Relation between plasma brain-derived neurotrophic factor and nerve growth factor in the male patients with alcohol dependence

Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are thought to be related to neuroprotection in cell culture and animal studies. Our aim was to verify the changes in human plasma BDNF and NGF concentrations induced by chronic alcohol use. Forty-one male patients with alcohol dependence were sampled the next morning of admission and compared with 41 healthy male subjects. Plasma BDNF and NGF were assayed using an enzyme-linked immunosorbent assay (ELISA). Mean plasma BDNF level was significantly higher in the patients with alcohol dependence (3502.21+/-1726.9 pg/mL) compared with the healthy subjects (861.75+/-478.9 pg/mL) (P=.000). Mean plasma NGF level was also significantly higher in patients with alcohol dependence (137.64+/-32.7 pg/mL) than in healthy subjects (112.61+/-90.2 pg/mL) (P=.012). Plasma BDNF and NGF levels showed significant negative correlation in alcohol dependence group (r=-0.388, P=.012). Increased plasma BDNF and NGF with negative correlation in alcohol-dependent patients may have some role in the regeneration of damage done by chronic alcohol use.

Association between Val66Met brain-derived neurotrophic factor (BDNF) gene polymorphism and post-treatment relapse in alcohol dependence

BACKGROUND

The purpose of this study was to examine relationships between genetic markers of central serotonin (5-HT) and dopamine function, and risk for post-treatment relapse, in a sample of alcohol-dependent patients.

METHODS

The study included 154 patients from addiction treatment programs in Poland, who met DSM-IV criteria for alcohol dependence. After assessing demographics, severity of alcohol use, suicidality, impulsivity, depression, hopelessness, and severity of alcohol use at baseline, patients were followed for approximately 1 year to evaluate treatment outcomes. Genetic polymorphisms in several genes (TPH2, SLC6A4, HTR1A, HTR2A, COMT, and BDNF) were tested as predictors of relapse (defined as any drinking during follow-up) while controlling for baseline measures.

RESULTS

Of 154 eligible patients, 123 (80%) completed follow-up and 48% (n = 59) of these individuals relapsed. Patients with the Val allele in the Val66Met BDNF polymorphism and the Met allele in the Val158Met COMT polymorphism were more likely to relapse. Only the BDNF Val/Val genotype predicted post-treatment relapse [odds ratio (OR) = 2.62; p = 0.019], and time to relapse (OR = 2.57; p = 0.002), after adjusting for baseline measures and other significant genetic markers. When the analysis was restricted to patients with a family history of alcohol dependence (n = 73), the associations between the BDNF Val/Val genotype and relapse (OR = 5.76, p = 0.0045) and time to relapse (hazard ratio = 4.93, p = 0.001) were even stronger.

CONCLUSIONS

The Val66Met BDNF gene polymorphism was associated with a higher risk and earlier occurrence of relapse among patients treated for alcohol dependence. The study suggests a relationship between genetic markers and treatment outcomes in alcohol dependence. Because a large number of statistical tests were conducted for this study and the literature on genetics and relapse is so novel, the results should be considered as hypothesis generating and need to be replicated in independent studies.

NGF plasma levels increase due to alcohol intoxication and decrease during withdrawal

Recent studies show that alcohol dependence is associated with alterations in plasma levels of nerve growth factor (NGF). The aim of this study was to further elucidate reported alterations in NGF plasma levels during alcohol intoxication and withdrawal. Therefore, we assessed NGF plasma levels by enzyme-linked immunosorbent assay (ELISA) on admission (day 0) and day 7 of alcohol withdrawal in male alcohol dependent patients (n=75) in comparison to healthy controls (n=44). We found significant higher (U=1005.0, p<0.001) NGF plasma levels in the alcohol-dependent patients. Subgroup analysis showed significant higher (U=-2.934, p=0.003) NGF plasma levels in patients suffering from acute alcohol intoxication (group A) than in early abstinent patients (group B). From day 0 to day 7 of alcohol withdrawal NGF plasma levels decreased significantly in both groups (group A: Z=-3.118, p=0.002, group B: Z=-2.103, p=0.035). Our results suggest that acute alcohol intoxication is associated with an increase in NGF plasma levels, which decrease during alcohol withdrawal. These results suggest that NGF plasma levels increase as part of a regulation mechanism that counteracts alcohol intoxication.

Decreased plasma brain-derived neurotrophic factor levels in patients with alcohol dependence

BACKGROUND

Many reports have suggested possible relationships between brain-derived neurotrophic factor (BDNF) and alcohol dependence. A protective effect of BDNF against ethanol-induced cell damage has been suggested, and this effect may contribute to the development or maintenance of alcohol dependence. This study was carried out in order to verify the significance of BDNF in alcohol dependence.

METHODS

Peripheral BDNF levels were measured in alcohol-dependent patients and control subjects using an enzyme-linked immunosorbent assay. A physician's interview and standardized questionnaire were used to obtain information regarding each patient's history of alcohol consumption.

RESULTS

The mean BDNF level was lower in the alcohol dependence group (389.5 +/- 501.7 pg/ml) than in the normal controls (822.5 +/- 420.7 pg/ml) by analysis of covariance (ANCOVA) (F = 25.79, p < 0.01). The mean BDNF level was lower in the alcohol-dependent patients with a positive family history of alcohol dependence (247.6 +/- 289.2 pg/ml) than in those with a negative family history of alcohol dependence (583.9 +/- 652.8 pg/ml) by ANCOVA (F = 6.51, p = 0.01). The BDNF levels did not correlate significantly with any of the variables analyzed in this study, including Beck depression inventory, state and trait anxiety inventory (STAI-S and T), and various drinking behaviors.

CONCLUSIONS

Changes in the levels of BDNF might play a role in the pathophysiology and inheritance of alcohol dependence.

Nerve growth factor in serum is a marker of the stage of alcohol disease

Long-term alcohol abuse has deleterious effects on the peripheral and central nervous system. Nerve growth factor (NGF) is a pleiotropic neurotrophic protein involved in development, maintenance of function and regeneration of nerve cells. We examined patients in different stages of alcohol disease and measured their NGF serum concentrations based on the hypothesis that these reflect the state of disease. We examined 57 patients suffering from alcohol-dependence for more than 2 years (DSM IV) on day 8 of a qualified withdrawal, 18 patients with Korsakoff's syndrome and 40 healthy controls. In addition to clinical examination, careful history taking and a standard neuropsychological test battery, serum NGF concentrations were measured by a highly sensitive enzyme-immunoassay. Of the 57 patients 9 had suffered from severe withdrawal delirium in the past, other clinical parameters were alike. Cognitive test performance did not differ from the control group. Mean NGF levels of controls amounted to 42.1pg/ml (S.D. 68.0); mean levels of patients with alcohol dependence were raised significantly to 401.5pg/ml (S.D. 932.6) without delirium in the past and even further to 3292.5pg/ml (S.D. 4879.6) with former withdrawal delirium. By contrast, patients with persistent amnestic disorder (Korsakoff's syndrome) showed values identical to the controls. NGF serum levels were significantly elevated in alcohol-dependent patients, more so in those with prior delirium. Their cognitive tests being normal, this possibly reflects the activity of NGF as an endogenous repair mechanism for damaged neurons. In accordance with this hypothesis, NGF values are "normal" in patients with persistent alcohol-related cognitive decline.