Glutamate levels in the ventromedial prefrontal cortex and resting‐state functional connectivity within reward circuits in alcohol‐dependent patients

Systematic review on resting-state fMRI in people with AUD and people who binge drink

Resting-state functional magnetic resonance imaging (rsfMRI) has become ubiquitous in neuroimaging to study disorders, including alcohol use disorder (AUD), given its potential to serve as a biomarker of psychiatric symptoms. The number of techniques, sample heterogeneity, and findings demand the assessment of results to identify potential biomarkers for the development of treatment. This systematic review aimed to synthesize the alcohol rsfMRI literature by summarizing the results by analysis approach and groups to examine these findings in the context of the neurobiology of addiction model. Three databases were systematically searched, resulting in the inclusion of 17 studies with a total of 784 participants (387 were people with AUD, 38 engaged in binge drinking, and 359 were controls). Seed-based functional connectivity studies were the most prominent. Compared to controls, people who binge drink and people with AUD showed greater connectivity of the Middle Frontal Gyrus-a region associated with the preoccupation/anticipation stage of the theory. Regions of the prefrontal and limbic cortex were most consistently reported in studies. The different types of analyses, sample size, and variability in the sample may have contributed to differences reported across studies. This review synthesizes and examines the results of different studies using the neurobiology of addiction theory, which may inform future studies on potential regions of interest, recruitment approaches, and analysis methods. Standardizing the methods for such a heterogeneous population could lead to more rapid development of neurobiologically-informed treatments for AUD.

Compensation patterns and altered functional connectivity in alcohol use disorder with and without Korsakoff's syndrome

Alcohol use disorder is a chronic disease characterized by an inappropriate pattern of drinking, resulting in negative consequences for the individual's physical, mental and social health. Korsakoff's syndrome is a complication of alcohol use disorder and is characterized by severe memory and executive deficits. The fronto-cerebellar and Papez circuits are structurally affected in patients with alcohol use disorder with and without Korsakoff's syndrome. The first objective of the present study was to measure the effect of chronic and excessive alcohol consumption on resting-state functional connectivity of these two functional brain networks. The second objective was to identify, for the first time, resting-state functional connectivity abnormalities specific to amnesic patients with Korsakoff's syndrome. In the present study, a neuropsychological assessment and a resting-state functional magnetic resonance imaging examination were conducted in 31 healthy controls (43.6 ± 6.1 years) and 46 patients (46.6 ± 9.1 years) with alcohol use disorder including 14 patients with Korsakoff's syndrome (55.5 ± 5.3 years) to examine the effect of chronic and heavy alcohol consumption on functional connectivity of the fronto-cerebellar and the Papez circuits at rest and the specificity of functional connectivity changes in Korsakoff's syndrome compared to alcohol use disorder without Korsakoff's syndrome. The resting-state functional connectivity analyses focused on the nodes of the fronto-cerebellar and Papez circuits and combined region of interest and graph theory approaches, and whether these alterations are associated with the neuropsychological profile. In patients pooled together compared to controls, lower global efficiency was observed in the fronto-cerebellar circuit. In addition, certain regions of the fronto-cerebellar and Papez circuits were functionally hyperconnected at rest, which positively correlated with executive functions. Patients with Korsakoff's syndrome showed lower resting-state functional connectivity, lower local and global efficiency within the Papez circuit compared to those without Korsakoff's syndrome. Resting-state functional connectivity positively correlated with several cognitive scores in patients with Korsakoff's syndrome. The fronto-cerebellar and Papez circuits, two normally well-segregated networks, are functionally altered by alcohol use disorder. The Papez circuit attempts to compensate for deficits in the fronto-cerebellar circuit, albeit insufficiently as evidenced by patients' overall lower cognitive performance. Korsakoff's syndrome is characterized by altered functional connectivity in the Papez circuit known to be centrally involved in memory.

Effect of family intervention on relapse rate of Chinese patients with alcohol-dependent

Objective

This study explored the impact of a family intervention on the relapse rate of Chinese patients with alcohol dependence.

Methods

A total of 151 male patients with alcohol dependence who were discharged from the Substance Dependence Department of the Wenzhou Seventh People's Hospital from January to December 2020 were selected. They were divided into the control (n = 73) and experimental (n = 78) groups. Patients in both groups received routine alcohol cessation treatment. Moreover, patients in the experimental group were followed up by a professional psychiatrist to carry out individual family intervention. The Family Function Rating Scale (FAD), a Self-made general information questionnaire, and the Chinese version of the Family Intimacy and Adaptability Scale (FACESI-CV) were performed. Re-drinking rate and readmission rate were assessed.

Results

Family intervention could reduce relapse rate (31, 39.74%) and rehospitalization (27, 34.62%) compared with the control group. After family training, FAD factor scores were improved in the experiment group in comparison with the control group. Family training improved communication (18.2 ± 3.7), role (20.8 ± 2.5), emotional response (10.8 ± 1.8), emotional involvement (13.7 ± 1.2), behavioral control (19.8 ± 1.2), and overall functionality (23.5 ± 2.1) in the experiment group in comparison with the control group. After family training, intimacy (70.5 ± 8.7) and adaptability (64.1 ± 6.9) in the experiment group was higher than in the control group. After family intervention, Michigan Alcohol Dependence Scale (MAST) (9.21 ± 0.68) and Short-Form 36 (SF-36) (80.32 ± 4.47) in the experiment group were higher than the control group.

Conclusion

Family intervention for families of patients with alcohol dependence can improve their family function, increase their family intimacy and adaptability, and reduce the rate of relapse.

Prefrontal cortex glutamatergic adaptations in a mouse model of alcohol use disorder

Alcohol use disorder (AUD) produces cognitive deficits, indicating a shift in prefrontal cortex (PFC) function. PFC glutamate neurotransmission is mostly mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type ionotropic receptors (AMPARs); however preclinical studies have mostly focused on other receptor subtypes. Here we examined the impact of early withdrawal from chronic ethanol on AMPAR function in the mouse medial PFC (mPFC). Dependent male C57BL/6J mice were generated using the chronic intermittent ethanol vapor-two bottle choice (CIE-2BC) paradigm. Non-dependent mice had access to water and ethanol bottles but did not receive ethanol vapor. Naïve mice had no ethanol exposure. We used patch-clamp electrophysiology to measure glutamate neurotransmission in layer 2/3 prelimbic mPFC pyramidal neurons. Since AMPAR function can be impacted by subunit composition or plasticity-related proteins, we probed their mPFC expression levels. Dependent mice had higher spontaneous excitatory postsynaptic current (sEPSC) amplitude and kinetics compared to the Naïve/Non-dependent mice. These effects were seen during intoxication and after 3-8 days withdrawal, and were action potential-independent, suggesting direct enhancement of AMPAR function. Surprisingly, 3 days withdrawal decreased expression of genes encoding AMPAR subunits (Gria1/2) and synaptic plasticity proteins (Dlg4 and Grip1) in Dependent mice. Further analysis within the Dependent group revealed a negative correlation between Gria1 mRNA levels and ethanol intake. Collectively, these data establish a role for mPFC AMPAR adaptations in the glutamatergic dysfunction associated with ethanol dependence. Future studies on the underlying AMPAR plasticity mechanisms that promote alcohol reinforcement, seeking, drinking and relapse behavior may help identify new targets for AUD treatment.