Neurogenetic adaptive mechanisms in alcoholism

Clinical, genetic, and neuropsychopharmacological studies of developmental factors in alcoholism are providing a better understanding of the neurobiological bases of personality and learning. Studies of the adopted-away children of alcoholics show that the predisposition to initiate alcohol-seeking behavior is genetically different from susceptibility to loss of control after drinking begins. Alcohol-seeking behavior is a special case of exploratory appetitive behavior and involves different neurogenetic processes than do susceptibility to behavioral tolerance and dependence on the antianxiety or sedative effects of alcohol. Three dimensions of personality have been described that may reflect individual differences in brain systems modulating the activation, maintenance, and inhibition of behavioral responses to the effects of alcohol and other environmental stimuli. These personality traits distinguish alcoholics with different patterns of behavioral, neurophysiological, and neuropharmacological responses to alcohol.

Inheritance of alcohol abuse. Cross-fostering analysis of adopted men

The inheritance of alcoholism was studied in 862 Swedish men adopted by nonrelatives at an early age. Both the congenital and postnatal backgrounds of the adoptees modify their risk for alcohol abuse. We distinguish two forms of alcoholism that have distinct genetic and environmental causes and differ in their association with criminality, severity of alcohol abuse, and the frequency of expression in biological mothers. Postnatal milieu determines the frequency and severity of expression of the common type of susceptibility in both men and women. In contrast, the less common type is highly heritable in men but is seldom expressed in mothers of affected men.

Finite mixture modeling with mixture outcomes using the EM algorithm

This paper discusses the analysis of an extended finite mixture model where the latent classes corresponding to the mixture components for one set of observed variables influence a second set of observed variables. The research is motivated by a repeated measurement study using a random coefficient model to assess the influence of latent growth trajectory class membership on the probability of a binary disease outcome. More generally, this model can be seen as a combination of latent class modeling and conventional mixture modeling. The EM algorithm is used for estimation. As an illustration, a random-coefficient growth model for the prediction of alcohol dependence from three latent classes of heavy alcohol use trajectories among young adults is analyzed.

Gender differences in risk factors and consequences for alcohol use and problems

Women drink less alcohol and have fewer alcohol-related problems than men. Women appear to be less likely than men to manifest certain risk factors for alcohol use and problems and are more likely to have certain protective factors against these problems: women perceive greater social sanctions for drinking; women are less likely to have characteristics associated with excessive drinking including aggressiveness, drinking to reduce distress, behavioral undercontrol, sensation-seeking and antisociality; and women are more likely to have desirable feminine traits (e.g., nurturance) protective against excessive drinking. In addition, consequences of heavy alcohol use, or alcohol use disorders, appear to be more negative for women than men, at least in some domains: women suffer alcohol-related physical illnesses at lower levels of exposure to alcohol than men, and some studies suggest women suffer more cognitive and motor impairment due to alcohol than men; women may be more likely than men to suffer physical harm and sexual assault when they are using alcohol; heavy alcohol use in women is associated with a range of reproductive problems. Implications of these findings for future research and public health education campaigns are discussed.

The impact of adverse childhood experiences on health problems: evidence from four birth cohorts dating back to 1900

BACKGROUND

We examined the relationship of the number of adverse childhood experiences (ACE score) to six health problems among four successive birth cohorts dating back to 1900 to assess the strength and consistency of these relationships in face of secular influences the 20th century brought in changing health behaviors and conditions. We hypothesized that the ACE score/health problem relationship would be relatively "immune" to secular influences, in support of recent studies documenting the negative neurobiologic effects of childhood stressors on the developing brain.

METHODS

A retrospective cohort study of 17,337 adult health maintenance organization (HMO) members who completed a survey about childhood abuse and household dysfunction, as well as their health. We used logistic regression to examine the relationships between ACE score and six health problems (depressed affect, suicide attempts, multiple sexual partners, sexually transmitted diseases, smoking, and alcoholism) across four successive birth cohorts: 1900-1931, 1932-1946, 1947-1961, and 1962-1978.

RESULTS

The ACE score increased the risk for each health problem in a consistent, strong, and graded manner across four birth cohorts (P < 0.05). For each unit increase in the ACE score (range: 0-8), the adjusted odds ratios (ORs) for depressed affect, STDs, and multiple sexual partners were increased within a narrow range (ORs: 1.2-1.3 per unit increase) for each of the birth cohorts; the increase in risk for suicide attempts was stronger but also in a narrow range (ORs: 1.5-1.7).

CONCLUSIONS

Growing up with ACEs increased the risk of numerous health behaviors and outcomes for 20th century birth cohorts, suggesting that the effects of ACEs on the risk of various health problems are unaffected by social or secular changes. Research showing detrimental and lasting neurobiologic effects of child abuse on the developing brain provides a plausible explanation for the consistency and dose-response relationships found for each health problem across birth cohorts, despite changing secular influences.

A developmental perspective on alcohol use and heavy drinking during adolescence and the transition to young adulthood

OBJECTIVE

This article offers a developmental perspective on college drinking by focusing on broad developmental themes during adolescence and the transition to young adulthood.

METHOD

A literature review was conducted.

RESULTS

The transition to college involves major individual and contextual change in every domain of life; at the same time, heavy drinking and associated problems increase during this transition. A developmental contextual perspective encourages the examination of alcohol use and heavy drinking in relation to normative developmental tasks and transitions and in the context of students' changing lives, focusing on interindividual variation in the course and consequences of drinking and on a wide range of proximal and distal influences. Links between developmental transitions and alcohol use and other health risks are discussed in light of five conceptual models: Overload, Developmental Mismatch, Increased Heterogeneity, Transition Catalyst and Heightened Vulnerability to Chance Events. We review normative developmental transitions of adolescence and young adulthood, focusing on the domains of physical and cognitive development, identity, affiliation and achievement.

CONCLUSIONS

As shown in a selective review of empirical studies, these transitions offer important vantage points for examining increasing (and decreasing) alcohol and other drug use during adolescence and young adulthood. We conclude with a consideration of research and intervention implications.

The relationship between anxiety disorders and alcohol use disorders: a review of major perspectives and findings

It is generally agreed that problems related to alcohol use and anxiety tend to occur within the same individual ("comorbidity"); however, the cause of this association remains controversial. Three prominent perspectives are that anxiety disorder promotes pathological alcohol use, that pathological alcohol use promotes anxiety disorder and that a third factor promotes both conditions. We review laboratory, clinical, family, and prospective studies bearing on the validity of these explanatory models. Findings converge on the conclusion that anxiety disorder and alcohol disorder can both serve to initiate the other, especially in cases of alcohol dependence versus alcohol abuse alone. Further, evidence from clinical studies suggests that anxiety disorder can contribute to the maintenance of and relapse to pathological alcohol use. Relying heavily on pharmacological and behavioral laboratory findings, we tentatively propose that short-term anxiety reduction from alcohol use, in concert with longer-term anxiety induction from chronic drinking and withdrawal, can initiate a vicious feed-forward cycle of increasing anxiety symptoms and alcohol use that results in comorbidity.

Probability and predictors of transition from first use to dependence on nicotine, alcohol, cannabis, and cocaine: results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC)

BACKGROUND

This study aims to estimate general and racial-ethnic specific cumulative probability of developing dependence among nicotine, alcohol, cannabis or cocaine users, and to identify predictors of transition to substance dependence.

METHODS

Analyses were done for the subsample of lifetime nicotine (n=15,918), alcohol (n=28,907), cannabis (n=7389) or cocaine (n=2259) users who participated in the first and second wave of the National Epidemiological Survey on Alcohol and Related Conditions (NESARC). Discrete-time survival analyses were implemented to estimate the cumulative probability of transitioning from use to dependence and to identify predictors of transition to dependence.

RESULTS

The cumulative probability estimate of transition to dependence was 67.5% for nicotine users, 22.7% for alcohol users, 20.9% for cocaine users, and 8.9% for cannabis users. Half of the cases of dependence on nicotine, alcohol, cannabis and cocaine were observed approximately 27, 13, 5 and 4 years after use onset, respectively. Significant racial-ethnic differences were observed in the probability of transition to dependence across the four substances. Several predictors of dependence were common across the four substances assessed.

CONCLUSIONS

Transition from use to dependence was highest for nicotine users, followed by cocaine, alcohol and cannabis users. Transition to cannabis or cocaine dependence occurred faster than transition to nicotine or alcohol dependence. The existence of common predictors of transition dependence across substances suggests that shared mechanisms are involved. The increased risk of transition to dependence among individuals from minorities or those with psychiatric or dependence comorbidity highlights the importance of promoting outreach and treatment of these populations.

Animal models of alcoholism: neurobiology of high alcohol-drinking behavior in rodents

This review discusses efforts to develop rodent models for the study of neurobiological mechanisms underlying chronic alcohol drinking, alcoholism, and abnormal alcohol-seeking behavior. Selective breeding has produced stable lines of rats that reliably exhibit high and (for comparison purposes) low voluntary alcohol consumption. In addition, animal models of chronic ethanol self-administration have been developed in rodents, who do not have a genetic predisposition for high alcohol-seeking behavior, to explore environmental influences in ethanol drinking and the effects of physical dependence on alcohol self-administration. The selectively bred high-preference animals reliably self-administer ethanol by free-choice drinking and operantly respond for oral ethanol in amounts that produce pharmacologically meaningful blood alcohol concentrations (50 to 200 mg% and higher). In addition, the alcohol-preferring rats will self-administer ethanol by intragastric infusion. With chronic free-choice drinking, the high alcohol-preferring rats develop tolerance to the high-dose effects of ethanol and show signs of physical dependence after the withdrawal of alcohol. Compared with nonpreferring animals, the alcohol-preferring rats are less sensitive to the sedative-hypnotic effects of ethanol and develop tolerance more quickly to high-dose ethanol. Nonselected common stock rats can be trained to chronically self-administer ethanol following its initial presentation in a palatable sucrose or saccharin solution, and the gradual replacement of the sucrose or saccharin with ethanol (the sucrose/saccharin-fade technique). Moreover, rats that are trained in this manner and then made dependent by ethanol-vapor inhalation or liquid diet increase their ethanol self-administration during the withdrawal period. Both the selectively bred rats and common-stock rats demonstrate "relapse" and an alcohol deprivation effect following 2 or more weeks of abstinence. Systemic administration of agents that (1) increase synaptic levels of serotonin (5-HT) or dopamine (DA); (2) activate 5-HT1A, 5-HT2, D2, D3, or GABA(A) receptors; or (3) block opioid and 5-HT3 receptors decrease ethanol intake in most animal models. Neurochemical, neuroanatomical, and neuropharmacological studies indicate innate differences exist between the high alcohol-consuming and low alcohol-consuming rodents in various CNS limbic structures. In addition, reduced mesolimbic DA and 5-HT function have been observed during alcohol withdrawal in common stock rats. Depending on the animal model under study, abnormalities in the mesolimbic dopamine pathway, and/or the serotonin, opioid, and GABA systems that regulate this pathway may underlie vulnerability to the abnormal alcohol-seeking behavior in the genetic animal models.

The role of early life stress as a predictor for alcohol and drug dependence

RATIONALE

Genetic and environmental influences on the development of alcohol and drug dependence are equally important. Exposure to early life stress, that is unfortunately common in the general population, has been shown to predict a wide range of psychopathology, including addiction.

OBJECTIVE

This review will look at the characteristics of early life stress that may be specific predictors for adolescent and adult alcohol and drug dependence and will focus on studies in humans, non-human primates and rodents.

RESULTS

Experiencing maltreatment and cumulative stressful life events prior to puberty and particularly in the first few years of life is associated with early onset of problem drinking in adolescence and alcohol and drug dependence in early adulthood. Early life stress can result in permanent neurohormonal and hypothalamic-pituitary-adrenal axis changes, morphological changes in the brain, and gene expression changes in the mesolimbic dopamine reward pathway, all of which are implicated in the development of addiction. However, a large proportion of children who have experienced even severe early life stress do not develop psychopathology indicating that mediating factors such as gene-environment interactions and family and peer relationships are important for resilience.

CONCLUSIONS

There appears to be a direct pathway from chronic stress exposure in pre-pubertal children via adolescent problem drinking to alcohol and drug dependence in early adulthood. However, this route can be moderated by genetic and environmental factors. The role that gene-environment interactions play in the risk-resilience balance is being increasingly recognized.

Long-term consequences of childhood sexual abuse by gender of victim

BACKGROUND

Childhood sexual abuse (CSA) is a worldwide problem. Although most studies on the long-term consequences of CSA have focused on women, sexual abuse of both boys and girls is common. Thus, a comparison of the long-term effects of CSA by gender of the victim will provide perspective on the need for future research, prevention activities, and treatment of survivors.

METHODS

A retrospective cohort study was conducted from 1995 to 1997 among 17,337 adult HMO members in San Diego, California. Participants completed a survey about abuse or household dysfunction during childhood, and multiple other health-related issues. Multivariate logistic regression was used to examine the relationships between severity of CSA (intercourse vs no intercourse) and long-term health and social problems (substance use and abuse, mental illness, and current problems with marriage and family) by gender of victim. Models controlled for exposure to other forms of adverse childhood experiences that co-occur with CSA. Among men, the relationship between the gender of the CSA perpetrator to the outcomes was also examined.

RESULTS

Contact CSA was reported by 16% of males and 25% of females. Men reported female perpetration of CSA nearly 40% of the time, and women reported female perpetration of CSA 6% of the time. CSA significantly increased the risk of the outcomes. The magnitude of the increase was similar for men and women. For example, compared to reporting no sexual abuse, a history of suicide attempt was more than twice as likely among both men and women who experienced CSA (p<0.05). Compared with those who did not report CSA, men and women exposed to CSA were at a 40% increased risk of marrying an alcoholic, and a 40% to 50% increased risk of reporting current problems with their marriage (p<0.05).

CONCLUSIONS

In this cohort of adult HMO members, experiencing CSA was common among both men and women. The long-term impact of CSA on multiple health and social problems was similar for both men and women. These findings strongly indicate that boys and girls are vulnerable to this form of childhood maltreatment; the similarity in the likelihood for multiple behavioral, mental, and social outcomes among men and women suggests the need to identify and treat all adults affected by CSA.

Childhood personality predicts alcohol abuse in young adults

431 children (233 boys, 198 girls) born in Stockholm, Sweden, had a detailed behavioral assessment at 11 years of age, including a detailed interview with their school teachers, and at age 27 years were reevaluated to identify alcoholism or alcohol abuse. Specific predictions from a neurobiological learning theory about the role of heritable personality traits in susceptibility to alcohol abuse were tested in this prospective longitudinal study. Three dimensions of childhood personality variation were identified and rated without knowledge of adult outcome. These three dimensions (novelty-seeking, harm avoidance, and reward dependence) were largely uncorrelated with one another, and each was predictive of later alcohol abuse. Absolute deviations from the mean of each of the three personality dimensions were associated with an exponential increase in the risk of later alcohol abuse. High novelty-seeking and low harm avoidance were most strongly predictive of early-onset alcohol abuse. These two childhood variables alone distinguished boys who had nearly 20-fold differences in their risk of alcohol abuse: the risk of alcohol abuse varied from 4 to 75% depending on childhood personality.

Glutamatergic substrates of drug addiction and alcoholism

The past two decades have witnessed a dramatic accumulation of evidence indicating that the excitatory amino acid glutamate plays an important role in drug addiction and alcoholism. The purpose of this review is to summarize findings on glutamatergic substrates of addiction, surveying data from both human and animal studies. The effects of various drugs of abuse on glutamatergic neurotransmission are discussed, as are the effects of pharmacological or genetic manipulation of various components of glutamate transmission on drug reinforcement, conditioned reward, extinction, and relapse-like behavior. In addition, glutamatergic agents that are currently in use or are undergoing testing in clinical trials for the treatment of addiction are discussed, including acamprosate, N-acetylcysteine, modafinil, topiramate, lamotrigine, gabapentin and memantine. All drugs of abuse appear to modulate glutamatergic transmission, albeit by different mechanisms, and this modulation of glutamate transmission is believed to result in long-lasting neuroplastic changes in the brain that may contribute to the perseveration of drug-seeking behavior and drug-associated memories. In general, attenuation of glutamatergic transmission reduces drug reward, reinforcement, and relapse-like behavior. On the other hand, potentiation of glutamatergic transmission appears to facilitate the extinction of drug-seeking behavior. However, attempts at identifying genetic polymorphisms in components of glutamate transmission in humans have yielded only a limited number of candidate genes that may serve as risk factors for the development of addiction. Nonetheless, manipulation of glutamatergic neurotransmission appears to be a promising avenue of research in developing improved therapeutic agents for the treatment of drug addiction and alcoholism.

Psychological stress, drug-related cues and cocaine craving

RATIONALE

While several environmental situations may produce cocaine craving, there is little research on whether patterns of drug cue reactivity are similar across different environmental situations.

OBJECTIVE

This study examined whether two different environmental situations, psychological stress and drug cues, produce similar or varying patterns of cue reactivity in 20 cocaine dependent individuals.

METHODS

All subjects participated in a single laboratory session and were exposed to stress, drug cues and neutral-relaxing imagery conditions. Cocaine and alcohol craving, emotion state ratings, subjective anxiety, heart rate and salivary cortisol measures were assessed.

RESULTS

Significant increases in cocaine and alcohol craving were observed with stress and drug cues imagery but not with neutral-relaxing imagery. In addition, stress and drug cues situations produced similar increases in subjective anxiety, heart rate and salivary cortisol levels. Significant increases in negative emotion ratings and decreases in positive emotion ratings were found for stress and drug cues conditions as compared to the neutral condition.

CONCLUSIONS

The findings indicate that a similar and comparable pattern of cue reactivity is induced by stress and drug cue manipulations. Furthermore, the comparable increases in subjective anxiety and negative affect observed with stress-induced and drug cue-induced craving provides support for the negative reinforcement model of drug craving and relapse. The negative affectivity co-occurring with the craving state appears to be an important target in the development of new treatments for cocaine dependence.

Alcohol dependence produced in mice by inhalation of ethanol: grading the withdrawal reaction

Intoxicating blood levels of ethanol are maintained for several days in mice housed in an atmosphere of ethanol vapor. On removal from the alcohol, all the mice develop withdrawal signs. The signs can be graded to indicate the time course and intensity of the withdrawal reaction.

Psychosis, victimisation and childhood disadvantage: evidence from the second British National Survey of Psychiatric Morbidity

BACKGROUND

Adverse early circumstances may be more common in people who later develop psychotic disorders.

AIMS

To use data from the second British National Survey of Psychiatric Morbidity to examine associations between psychotic disorders and a number of early victimisation experiences.

METHOD

Psychiatric disorders were identified through structured assessment of adults resident in private households in Britain (n=8580). Respondents were asked whether they had experienced selected events displayed on cards.

RESULTS

Compared with respondents with other psychiatric disorders or with none, the prevalence of every experience bar one was significantly elevated in those with definite or probable psychosis. The largest odds ratio was for sexual abuse. Controlling for depressed mood somewhat reduced the odds ratios for the individual experiences.

CONCLUSIONS

In people with psychosis, there is a marked excess of victimising experiences, many of which will have occurred during childhood. This is suggestive of a social contribution to aetiology.

Advances in the science and treatment of alcohol use disorder

Alcohol is a major contributor to global disease and a leading cause of preventable death, causing approximately 88,000 deaths annually in the United States alone. Alcohol use disorder is one of the most common psychiatric disorders, with nearly one-third of U.S. adults experiencing alcohol use disorder at some point during their lives. Alcohol use disorder also has economic consequences, costing the United States at least $249 billion annually. Current pharmaceutical and behavioral treatments may assist patients in reducing alcohol use or facilitating alcohol abstinence. Although recent research has expanded understanding of alcohol use disorder, more research is needed to identify the neurobiological, genetic and epigenetic, psychological, social, and environmental factors most critical in the etiology and treatment of this disease. Implementation of this knowledge in clinical practice and training of health care providers is also needed to ensure appropriate diagnosis and treatment of individuals suffering from alcohol use disorder.

The impact of childhood abuse and neglect on adult mental health: a prospective study

This paper examines the impact of three types of victimization in childhood--sexual abuse, physical abuse, and neglect--on lifetime measures of mental health among adults. In contrast to research that relies on retrospective recall of childhood victimization, this work uses a prospective sample gathered from records of documented court cases of childhood abuse and neglect in a midwestern city around 1970. These subjects were interviewed about twenty years later. In addition, this research compares outcomes of the 641 members of the abuse and neglect group with a matched control group of 510 persons who did not have documented cases of abuse or neglect. The results indicate that men who were abused and neglected as children have more dysthymia and antisocial personality disorder as adults than matched controls, but they did not have more alcohol problems. Abused and neglected women report more symptoms of dysthymia, antisocial personality disorder, and alcohol problems than controls. After controlling for stressful life events, however, childhood victimization had little direct impact on any lifetime mental health outcome. This research indicates the importance of adopting an approach that places childhood victimization in the context of other life stressors and of prospective changes over the life course.

An internalizing pathway to alcohol use and disorder

Research emanating from the field of developmental science indicates that initial risk factors for alcohol use and disorder can be evident in early childhood. One dominant developmental pathway connecting these initial risk factors with subsequent alcohol involvement focuses on the central role of disinhibited or externalizing behaviors. In the current paper, we delineate a second pathway that focuses on internalizing symptomatology. Several studies indicate that internalizing symptoms in early and middle childhood predict alcohol involvement in adolescence and young adulthood. We use a developmental psychopathology framework to describe a risk model that traces the potential developmental markers of this internalizing pathway and to consider the relation between the internalizing pathway and the more widely researched externalizing pathway. We outline the markers of risk in this pathway and conclude with a discussion of the implications of this model for prevention efforts and future research. In this manner, we strive for a translational goal, linking our existing understanding of internalizing processes and alcohol use and disorder with our efforts to develop effective prevention programs.

The development of alcohol use disorders

Pathological alcohol use is a complex and costly problem. This chapter focuses on recent developments in the etiology of alcohol use disorders. Literature is reviewed from the fields of epidemiology, genetics, personality, neuropsychology, parenting, and social influences. In addition, theoretical models that describe pathways to the development of alcohol use disorders are presented. Particular emphasis is given to ways in which genetic, environmental, psychopharmacological, and personological literatures can inform one another.

The clinical implications of primary diagnostic groups among alcoholics

Interviews with patients and two resource persons were used to determine primary psychiatric diagnoses in 577 consecutive men entering an alcohol treatment program (ATP) at a veterans hospital. Twelve months later, about 95% of the sample were successfully followed up with a patient and resource person interview to establish the clinical course over the year for the four most populous diagnostic subgroups. At intake into the treatment program, the 432 group 1 primary alcoholic men were older, had a later age at onset of alcoholism, demonstrated a lower intensity of drinking, had fewer antisocial problems, and used fewer categories of drugs than the 60 men in group 2 with primary drug abuse and the 40 men in group 3 with primary antisocial personality disorder. During the follow-up, men in groups 2 and 3 had a greater likelihood of drug use, more police and social problems, and demonstrated higher (more adverse) outcomes on a clinical outcome scale. The nine group 4 men with primary affective disorder at intake demonstrated an increased risk for past suicide attempts and psychiatric care and had a higher rate of affective disorder in first-degree family members. These findings underscore the importance of distinguishing between symptoms (eg, sadness or antisocial problems) and diagnoses and the need to establish primary and secondary labels in substance abusers.

Patterns of gene expression are altered in the frontal and motor cortices of human alcoholics

Alcoholism is a major health problem in Western countries, yet relatively little is known about the mechanisms by which chronic alcohol abuse causes the pathologic changes associated with the disease. It is likely that chronic alcoholism affects a number of signaling cascades and transcription factors, which in turn result in distinct gene expression patterns. These patterns are difficult to detect by traditional experiments measuring a few mRNAs at a time, but are well suited to microarray analyses. We used cDNA microarrays to analyze expression of approximately 10 000 genes in the frontal and motor cortices of three groups of chronic alcoholic and matched control cases. A functional hierarchy was devised for classification of brain genes and the resulting groups were compared based on differential expression. Comparison of gene expression patterns in these brain regions revealed a selective reprogramming of gene expression in distinct functional groups. The most pronounced differences were found in myelin-related genes and genes involved in protein trafficking. Significant changes in the expression of known alcohol-responsive genes, and genes involved in calcium, cAMP, and thyroid signaling pathways were also identified. These results suggest that multiple pathways may be important for neuropathology and altered neuronal function observed in alcoholism.

Alcohol, amines, and alkaloids: a possible biochemical basis for alcohol addiction

Tetrahydropapaveroline is a benzyltetrahydroisoquinoline alkaloidderivative of the biogenic amine, dopnmine. Alcohol, by way of its primary metabolite, acetaldehyde, competitively inhibits nicotinamide-adenine Sinucleotide-linked aldehyde dehydrogenase and augments the formation of tetrahydropapaveroline in vitro. The limited capacity of brain to oxidize aldehydes may be of pharmacological importance because it facilitates the production of tetrahydropapaveroline in the presence of drugs which inhibit this enzyme.