Factors influencing monoamine metabolites and tryptophan in patients with alcohol dependence

Intensity dependence of auditory evoked potentials as an indicator of central serotonergic neurotransmission: a new hypothesis

Because of the increasing importance of the central serotonergic neurotransmission for pathogenetic concepts and its role as a target of pharmacotherapeutic interventions in psychiatry, reliable indicators of this system are needed. It is proposed that the stimulus intensity dependence of auditory evoked N1/P2-component, which is probably modulated by cortical serotonergic innervation, may be a useful and noninvasive indicator of behaviorally relevant aspects of serotonergic activity. Converging evidence from our own studies as well as from the literature suggests that a pronounced intensity dependence of auditory evoked N1/P2-component reflects low central serotonergic neurotransmission. Recent findings concerning general functional aspects of the brain serotonin system reveal that this system is well qualified for adjusting individual levels of sensory processing ("set the tone"), especially in the primary auditory cortex in which the N1/P2-component is mainly generated. Dipole source analysis represents an important methodological advance in this context because it allows the separation of N1/P2-subcomponents generated in the primary auditory cortex from those generated in secondary auditory areas.

Cerebrospinal fluid variables among alcoholics lack seasonal variation

Seasonal influences on indices of serotonergic function, including cerebrospinal fluid (CSF) concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), have been reported in psychiatric patients and healthy volunteers. We examined seasonal differences in CSF concentrations of 5-HIAA among 135 alcoholics admitted to a research ward who had a lumbar puncture. No significant seasonal differences were found for either CSF concentrations of 5-HIAA or CSF concentrations of other monoamine metabolites or peptides. The possible explanations for these negative findings are discussed.

Anxiogenic behavior in rats during acute and protracted ethanol withdrawal: reversal by buspirone

This study investigated the effectiveness of buspirone in reversing the anxiogenic behaviors occurring during ethanol withdrawal as measured in the elevated plus-maze. In response to anxiogenic drugs, rats spend less time in and make fewer entries onto the open arms of an elevated plus-maze, whereas anxiolytic drugs produce opposite effects. In this study, rats were fed a liquid diet containing 4.5% ethanol for 7 days. Twelve h (acute withdrawal) and 7 days (protracted withdrawal) following cessation of the ethanol diet, rats were tested on the elevated plus-maze. During these withdrawal periods, the percent open-arm entries and time spent on the open arms were significantly reduced relative to animals fed an ethanol-free diet, suggestive of anxiogenic-like symptoms. Buspirone (0.32-1.25 mg/kg) dose dependently reversed the withdrawal-induced decreases in open-arm activity. The anxiolytic-like activity of buspirone observed during ethanol withdrawal may be due to a reduction in serotonergic neurotransmission through activation of presynaptic 5-HT1A autoreceptors. The results obtained in this study suggest that pharmacotherapy with selective 5-HT1A agonists may be beneficial in alleviation of anxiety during ethanol withdrawal.

Medicalizing the drug war

Recent findings in the field of psychopharmacology pertain to the abuse of drugs and alcohol among criminal offenders and have implications for new management techniques. Drugs of abuse exert their effects on areas of the brain responsible for pleasure, providing a powerful reinforcement for drug usage. Furthermore, there is a prevalence of psychological, psychiatric and social dysfunctions that antedate drug use which are identifiable at an early age. It is suggested that drugs of abuse differentially influence users via these biological, psychological and social mechanisms, reinforcing the development of serious and chronic abuse in a vulnerable subgroup. Studies of drug abuse specially indicate that within this subgroup, antisocial behavior precedes and exacerbates drug abuse, and multiple risk factors contribute to the concomitant development of criminality and drug abuse. Early detection and comprehensive treatment of underlying disorders that may both precipitate and result from drug abuse promise to improve possibilities for prevention and reducing relapse rates. Furthermore, the inclusion of pharmacologic treatments may further enhance the success of conventional drug treatments. This article proposes that incorporating scientific data and medicalizing our approach to drug abuse is essential to win the war against drugs.

Blood serotonin and tryptophan in Tourette syndrome

Blood serotonin and tryptophan levels were studied in 1,440 individuals. These included patients with Tourette syndrome (TS), attention deficit hyperactivity disorder (ADHA), or ADHD with a family history of TS (ADHD 2 degrees TS); relatives (parents, sibs) of these patients; other patients with TS-like disorders; and controls. There were significant decreases in the serotonin/platelet ratio (P = 0.0001) and in tryptophan (P less than 0.0001) in unmedicated patients with TS. Parents of TS patients showed a comparable, significant decrease in serotonin/platelet ratio (P less than 0.0001) and in tryptophan (P less than 0.0001), and there was no difference between parents with and without symptoms. This suggested that these were trait markers for the Gts gene and agrees with the proposal that TS patients are homozygous for Gts gene and that both parents are Gts gene carriers. Although there was no decrease in the serotonin/platelet ratio in ADHD patients, tryptophan levels were significantly decreased and there was a significant decrease in both the serotonin/platelet ratio and in tryptophan in the parents of patients with ADHD including those without a family history of TS. This is consistent with a close link between TS and ADHD. The basic defect may be a dysregulation of serotonin metabolism. The low blood serotonin and tryptophan levels in TS are consistent with the wide range of behavioral disorders seen in TS and suggest tryptophan oxygenase as a possible candidate gene.

A cerebrospinal fluid study of the pathophysiology of panic disorder associated with alcoholism

In order to investigate the neurochemistry of panic disorder in alcoholics, we measured various cerebrospinal fluid (CSF) parameters in subjects with both conditions and compared them with an age- and sex-matched population of alcoholics and normal controls. When height, age and weight were covaried, subjects with panic disorder had higher levels of B-endorphin in CSF. There were no differences in other CSF measures between the groups. Alcoholics with panic disorder had higher plasma MHPG concentrations compared with alcoholics without panic disorder but these were not statistically different from controls.

Altered pineal serotonin binding in some suicides

Serotonergic abnormalities have been regularly reported in the brains of suicide victims. Because of evidence that pineal function is altered in depressed subjects and that serotonin-releasing axons may innervate the pineal, we assayed tritiated serotonin binding in a series of control and suicide pineals. High affinity binding was present, and there were apparent differences between some suicides and controls.

Serotonin uptake blockers and the treatment of alcoholism

There is growing research and clinical interest in the role of brain serotonin in regulating alcohol consumption, based on two lines of evidence: negative correlations between brain serotonin levels and spontaneous alcohol consumption in rodents, and decreased alcohol intake produced by drug-induced increases in brain serotonin activity in rodents and humans. Specific blockers of neuronal serotonin uptake, such as citalopram, fluoxetine, and zimelidine, are the major drugs used in such studies. More than a dozen studies have consistently found that such specific serotonin uptake blockers reduce alcohol preference and intake in rodents, whereas nonspecific monoamine uptake blockers (e.g., amitriptyline, doxepin) do not. The effect begins within 1 hr of administration, wears off within several days of stopping drug, and often shows tolerance after 4-10 days of daily administration (the opposite time course from antidepressant action in humans). In four human, double-blind, placebo-controlled studies, citalopram (40 mg but not 20 mg daily), fluoxetine (80 mg daily), and zimelidine (200 mg more than 300 mg daily) significantly reduced alcohol intake 10-26% in social drinkers, early problem drinkers, and chronic alcoholics. The effect occurred within a few days, wore off within several days of stopping drug, and lasted throughout the 2-4 weeks of drug administration, except that in the fluoxetine study with chronic alcoholics the effect was significant only during the first week. The reduced alcohol intake was not due to sedation, antidepression, or antianxiety effects, or an aversive drug-alcohol interaction, but could be explained in part by decreased appetitive behavior (two studies found that subjects lost weight) or a conditioned (taste) aversion to alcohol promoted by serotonin (as occurs in animals). Further research is also needed to clarify the neuropharmacological mechanism of action, since the alcohol intake-reducing effects in rodents are not blocked by serotonin receptor antagonists or brain serotonin depletion. Regardless of mechanism, serotonin uptake blockers offer a potentially promising new treatment for alcoholism.

Treatment of chronic organic mental disorders associated with alcoholism

Considering the magnitude of the problem, the treatment of alcoholism-associated chronic organic mental disorders has not been extensively studied. Alcoholic organic brain disease is heuristically viewed as the admixture of clinical syndromes of impairment [alcoholic amnestic disorder or Korsakoff's psychosis (KP) and dementia associated with alcoholism (DAA)], each with its distinguishing cognitive, neuropathological, and neurochemical characteristics. Differences between KP and DAA are highlighted by studies that compare KP patients with those having Alzheimer's disease or depression. Furthermore, treatment of cognitive deficits in KP and DAA may be modeled after strategies that have proved effective for these other neuropsychiatric disorders. Although abstinence and proper nutrition remain the cornerstones of treatment, pharmacological modification of neurotransmitter function and/or enhancement of cerebral metabolism combined with behavioral methods may also be beneficial. Serotonergic approaches to improve memory in detoxified alcoholics may also reduce alcohol intake, and this has implication for treatment of less impaired alcoholics.

Reduced central serotonin turnover in a subgroup of alcoholics?

We review cerebrospinal fluid (CSF) studies suggesting on association between low CSF levels of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAAA) and suicidal and impulsive behaviour and alcoholism. Relatively high percentages of alcoholics attempt and commit suicide and have impulsive antisocial personality disorder. Therefore, we suggest that there may be a sizable subgroup of alcoholics who have a reduced central serotonin turnover.

Test for decreased serotonin/tryptophan metabolite ratios in abstinent alcoholics

A segment of the population has a defect in the metabolism of tryptophan that causes a lowered concentration of serotonin in the central nervous system and indicates a predisposition towards chronic alcoholism. The metabolic defect in tryptophan metabolism is in the pathway between tryptophan and 5-hydroxyindoleacetic acid (5-HIAA) but not in the other pathways of tryptophan metabolism. A test using HPLC with amperometric detection was developed to detect the presence of an impaired serotonin metabolic pathway and therefore indicate a predisposition towards chronic alcoholism. The test used a ratio between 5-HIAA and two metabolites (indoleacetic acid and anthranilic acid) from the other pathways of tryptophan metabolism to indicate the presence or absence of an impaired serotonin metabolic pathway while correcting for variations in the concentration of urine.

Homicide, suicide and CSF 5-HIAA

Concentrations of 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 4-hydroxy-3-methoxyphenyl glycol (HMPG) in lumbar spinal fluid were measured by mass fragmentography in 16 men convicted for criminal homicide, 22 men who had attempted suicide, and 39 healthy male control subjects. Those men who had killed a sexual partner, and those who had attempted suicide, had lower levels of the serotonin metabolite, 5-HIAA in spinal fluid than the controls. It is suggested that low levels of 5-HIAA in spinal fluid reflect a disorder of serotonin turnover, which makes the individual more prone to acts of violence in states of emotional turmoil.

Thyroid stimulation test in healthy subjects and psychiatric patients

Fifteen healthy women and 64 female psychiatric inpatients (major depression: 17, schizophrenia: 24, alcohol dependence: 9, and adjustment disorder: 14 cases) without identifiable thyroid dysfunction were investigated with the TRH test under comparable circumstances. Although all patient groups showed some tendency toward lower baseline TSH and smaller TRH-induced TSH responses, only patients with major depression demonstrated marked, statistically significant differences from controls in both variables. Women with alcohol dependence (in the early withdrawal period) showed significantly decreased TSH responses to TRH but only a weak tendency to lower basal TSH levels. Intergroup differences in the TSH response remained significant after correction for basal TSH by analysis of covariance. Neither variables correlated significantly with age, weight or body height, but baseline TSH correlated with body surface. The TRH test, using only 0.2 mg TRH for stimulation, seemed to be useful for identifying major depression and showed that early withdrawal from alcohol may be a factor to be considered in similar studies.

CSF monoamine metabolites of depressed patients during illness and after recovery

Repeated lumbar punctures in 16 healthy volunteers showed reproducible concentrations of 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) in cerebrospinal fluid (CSF). In seven depressed patients, studied during two or three illness periods, the metabolite concentrations were also fairly stable. In 11 patients CSF concentrations of 5-HIAA, but not of HVA, were higher after recovery than during depression. This increase of 5-HIAA after recovery was confined to patients whose initial serotonin metabolite levels were low. The finding constitutes further evidence of a biochemical heterogeneity within the depressive disorders, and suggests that patients whose CSF 5-HIAA is low during a depressive episode may have a less stable serotonin system than other patients with depressive illness.

Amine metabolites, neuroendocrine findings, and personality dimensions as correlates of suicidal behavior

Levels of 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) were measured in the cerebrospinal fluid (CSF) of 62 female inpatients with major depression (n = 19), schizophrenic disorder (n = 18), alcohol dependence (n = 13), and other disorders (n = 12). Nineteen patients had attempted suicide immediately before admission, and six had used violent methods. Fifty-three patients received a dexamethasone suppression test (DST) following lumbar puncture and all completed the Marke-Nyman Temperament Scale (Hungarian version) within 10 days. CSF 5-HIAA was significantly lower in patients who had made violent suicide attempts, but did not differ between suicide attempters who had taken drug overdoses and nonattempters. CSF HVA showed no significant differences. Dexamethasone nonsuppression occurred more frequently among attempters, but this difference did not reach statistical significance. Among the three personality dimensions of the Marke-Nyman Scale, validity was lower and stability higher in suicidal patients; both findings were more pronounced in the violent subgroup. CSF 5-HIAA and Marke-Nyman validity were inversely correlated to each other in all three subgroups, and violent attempters could be separated from the other two groups by their simultaneously low CSF 5-HIAA values and Marke-Nyman validity scores.

Tryptophan levels in human cerebrospinal fluid after acute and chronic ethanol consumption

The essential amino acid tryptophan was measured in human cerebrospinal fluid by a fluorometric high-performance liquid chromatographic method. Acute ethanol consumption (80 g) by healthy volunteers lead to a decrease in tryptophan levels during intoxication. After intoxication no difference from base levels was evident. Following ingestion of a higher dose (120 g) the mean levels of tryptophan remained unchanged. Alcoholics were found to have elevated tryptophan levels in the cerebrospinal fluid as compared to healthy subjects even after abstention from ethanol for several weeks.