Catecholamines and monoamine oxidase activity in anxiety

Altered coordination of the neuroendocrine response during psychosocial stress in subjects with high trait anxiety

Contradicting data are available on stress responsiveness in subjects with high anxiety. In the present study we tested the hypothesis that high trait anxiety is associated with impaired coordination of the stress response, rather than global hypo- or hyper-responsiveness. The sample consisted of subjects with high (n=15) and with low (n=12) trait anxiety. Subjects with middle-range levels of anxiety were excluded from the study. After psychological characterization, the volunteers were exposed to a public speech procedure. A spectrum of neuroendocrine parameters was measured before, during and after the procedure and the results were analyzed by exploratory statistics. Psychological characterization of subjects revealed a lower preference for task-oriented but a higher one for emotion-oriented coping strategies as well as lower scores on hardiness in subjects with high trait anxiety. After the speech procedure, differences in selected mood and personality characteristics were observed, with the anxious group scoring significantly higher in scales for stress, tiredness, arousal, anxiety and depression. Factor analysis revealed that one common factor grouped blood pressure, catecholamine concentrations in blood and heart rate in non-anxious subjects, while three distinct factors separated these parameters in anxious subjects. Correlation analysis in anxious subjects showed that lower adrenocorticotropin (ACTH) and cortisol responses during stress were associated with exaggerated perception of stress and worse mental performance. Our findings indicate that subjects with high anxiety have different relationships between specific neuroendocrine parameters, subjective perception of stress and Stroop test performance.

The Role of Noradrenergic and Dopaminergic Hyperactivity in the Development of Spontaneous Recurrence of Methamphetamine Psychosis and Susceptibility to Episode Recurrence

The role of dopaminergic activity in susceptibility of methamphetamine (MAP) psychosis (flashbacks) to subsequent spontaneous recurrences was studied. Plasma monoamine metabolite levels were assayed in 23 flashbackers, of whom 10 experienced a single flashback, 8 exhibited subsequent flashbacks and 5 with the last episode; 18 nonflashbackers with a history of MAP psychosis; 9 subjects with persistent MAP psychosis; and 19 MAP user and 10 nonuser controls. All flashbackers had undergone frightening stressful experiences during previous MAP use. Their flashbacks were triggered by mild psychosocial stressors. Plasma norepinephrine (NE) levels increased with the increase in plasma levels of 3-methoxytyramine (3-MT), an index of dopamine release, during flashbacks in the 23 flashbackers. Of these, the 8 with subsequent episodes had markedly increased NE levels and increased 3-methoxytyramine levels during flashbacks. However, the 5 flashbackers with the last episode had moderately increased NE levels, and the 10 with a single episode displayed small increases in NE levels during flashbacks. Their 3-MT levels did not significantly differ from the levels in the control groups. Thus, increased DA release in addition to robust noradrenergic hyperactivity in response to mild psychosocial stressors may be important in susceptibility to subsequent flashbacks.

Susceptibility to subsequent episodes of spontaneous recurrence of methamphetamine psychosis

We examine susceptibility to subsequent spontaneous recurrences of methamphetamine psychosis (i.e. flashbacks) in 11 flashbackers with a single episode and in nine flashbackers with subsequent episodes. All had undergone frightening stressful experiences during previous MAP use. Mild psychosocial stressors then triggered flashbacks. During flashbacks, the nine flashbackers with subsequent episodes had more markedly increased norepinephrine levels, with slightly increased 3-methoxytyramine levels. The duration of imprisonment in this subgroup approached significantly long levels than in the 11 flashbackers with a single episode. Robust noradrenergic hyperactivity with slightly increased dopamine release may therefore predict subsequent flashbacks. Longer exposure to distressing situations may also contribute to robust noradrenergic hyperactivity.

Studies on the psychosomatic functioning of ill-health according to Eastern and Western medicine 5. Psychosomatic characteristics of anxiety and anxiety-affinitive constitution

In successive studies of the psychosomatic functioning of ill-health according to Oriental and Western medicine in medical students, we established the existence of the psychosomatic characteristics we have provisionally termed the anxiety-affinitve constitution at the core of ill-health. Therefore, we conducted this research because our previous investigation showed this constitution included a high complexity of respiratory movement and eye movement with a significant correlation to the State Trait Anxiety Inventory (STAI). We examined the correlation between the STAI and somatic function of 88 medical students to identify the psychosomatic characteristics of anxiety and the anxiety-affinitive constitution. These tests included STAI, fractal (EEG, EOG, plethysmogram, respiratory curves, and EMG) and non-fractal (accelerated plethysmogram) dimension analyses, and malocclusion (based on Angle's classification). In particular, EOG, plethysmogram, and respiratory curves are known to have close association with trait anxiety. We were able to discover the correlation between (1) trait anxiety and thoracic and abdominal respiratory movements, and malocclusion (Class III), and (2) the correlation of state anxiety with thoracic respiratory movement, horizontal eye movement, a plethysmogram and an EEG-Pz (in males only). In subsequent study the relation between thoracic dominance and state-trait anxiety and between abdominal dominance and state-trait anxiety should be assessed to develop this research regarding the psychosomatic characteristics of anxiety and the anxiety-affinitive constitution. Further, it is essential to create an anxiety-affinitve constitution index based on multi-regression analysis.

Neurobiology of generalized anxiety disorder

On reviewing the literature on GAD and trying to summarize the various developments in the field of neurobiology of GAD, we see that a range of hypotheses try to explore and integrate the observations found into potentially meaningful theories. Abnormal serotonergic and GABAergic function occur in many patients with GAD. Functional imaging data have shown increased cortical activity and decreased basal ganglia activity in patients with GAD, which reverses with treatment, but it is apparent that no one theory is sufficiently comprehensive to propose a unitary hypothesis for the development of GAD and other anxiety disorders. GAD is a relatively new diagnosable condition, first introduced into the classification system of psychiatric disorders in 1980, and since then has undergone a series of changes in its conceptualization, with some investigators questioning the existence of the condition as a distinct entity. Any inferences that may be drawn from various studies must be guarded, and it is appropriate to compare studies using the same diagnostic criteria. Significant research has been done and may lead to exciting new discoveries in the treatment of anxiety disorders in general and GAD in particular. Gray's model of behavioral inhibition, in which the septohippocampal system acts by assessing stimuli for the presence of danger and, when that is detected, activates the behavioral-inhibition circuit, provides a neuroanatomic conceptualization that has been expanded by preclinical research. Some exciting work has been done on CRF and the concept of development, vulnerability, and kindling and some investigators have contributed to this area of interest. This concept supports the hypothesis that a genetic predisposition, coupled with early stress, in the crucial phases of development may result in a phenotype that is neurobiologically vulnerable to stress and may lower an individual's threshold for developing anxiety or depression on additional stress exposure. The pharmaceutical industry is exploring treatment options using CRF antagonists, and research on other neuropeptides, especially NPY, will be of interest. Research on neurosteroids also may bring the opportunity for pharmacologic treatment approaches. Future research on the startle reflex and on the NMDA and the metabotropic glutamate receptors is important. Future studies of a more homogenous patient population and using more sophisticated techniques, such as molecular genetic strategies and better imaging techniques, may answer some of the outstanding questions.

Noradrenergic mechanisms in stress and anxiety: II. Clinical studies

Studies in animals have shown a relationship between alterations in noradrenergic brain system function and behaviors of anxiety and fear. These findings have generated the hypothesis that the symptoms seen in patients with anxiety disorders may be related to alterations in noradrenergic function. A number of clinical studies have tested this hypothesis, utilizing measures of catecholaminergic function such as heart rate and blood pressure, measurement of norepinephrine and its metabolites in urine and plasma and adrenergic receptor binding in platelets, as well as pharmacological challenge to the noradrenergic system. Acute stressors, such as public speaking, have been associated with an increase in heart rate, blood pressure, and norepinephrine and its metabolites in urine and plasma. Findings in patients with panic disorder at baseline related to heart rate, blood pressure, baseline norepinephrine and its metabolites, and platelet adrenergic receptors have been mixed, while the most consistent findings have been blunted growth hormone response to clonidine and increased 3-methoxy-4-hydroxy-phenylethylene-glucol (MHPG) and anxiety following stimulation of the noradrenergic system with yohimbine. Baseline measures of noradrenergic function in patients with posttraumatic stress disorder (PTSD) have also been mixed, while an increased heart, blood pressure and norepinephrine response to traumatic reminders, as well as increased behavioral (as well as different brain metabolic) response to yohimbine, have been found in PTSD. There are fewer studies of noradrenergic function in the other anxiety disorders, and the findings there have not been consistent. These studies provide evidence for increased noradrenergic responsiveness in panic disorder and PTSD, although there does not appear to be an alteration in baseline noradrenergic function in these patients.

Psychophysiological and biochemical changes in patients with panic attacks in a defined situational arousal

A group of 27 patients with panic disorder with or without agoraphobia were compared with 10 control subjects before stress exposure. No statistically significant differences between patients and controls were found for the cardiovascular parameters. Skin conductance level and skin conductance reaction were significantly higher in the patient group. They also showed higher self-ratings in behavioural symptoms associated with anxiety. There were statistically significant higher venous plasma levels of norepinephrine in patients than in controls, although the epinephrine levels were similar. The number of binding sites of alpha 2-receptors and the affinity of 3H-yohimbine to the alpha 2-receptors on intact thrombocytes was statistically significantly lower in patients compared to controls. Significant differences between the gender groups of patients and controls were found for electrodermal activity and epinephrine levels. These data add further evidence to an overshooting activation of the noradrenergic pathway in patients with panic disorder, possibly based on a dysregulation of alpha 2-receptor.

Psychobiology of stage fright: the effect of public performance on neuroendocrine, cardiovascular and subjective reactions

Subjective, neuroendocrine and cardiovascular functions were studied in high- and low-anxious musicians performing privately and publicly. Musicians were designated as "high-anxious" if they reported at least one episode of performance-related tremor and as "low-anxious" if they never had experienced tremor while performing in public. All musicians performed privately and publicly while measurements of subjective, neuroendocrine and cardiovascular functions were made. Ratings of effort and distress were made prior to performance. Heart rate was monitored telemetrically before, during and after performance. Urinary epinephrine, norepinephrine and cortisol were sampled after public and private performance, respectively. Situational factors influenced most measures. Epinephrine, norepinephrine, cortisol, heart rate and ratings of distress but not effort increased from private to public performance. Heart rate was higher in high- than in low-anxious musicians during public performance but similar during private performance. The increase in neuroendocrine activation from private to public performance was similar in the high- and low-anxious groups. It is concluded that heart rate is a sensitive measure of both situational and individual determinants of performance-related distress.

Platelet MAO activity in personality disorders and normal controls

Platelet monoamine oxidase (MAO) activity has been related to several psychiatric disorders and personality dimensions. The purpose of this study was to measure platelet MAO activity in personality disorders and determine its relationship to symptoms analogous to sensation seeking. Twenty-eight males admitted to a psychiatric unit with a DSM-III-R diagnosis of personality disorder were compared to normal controls. Patients with Axis I diagnoses other than adjustment disorder were excluded. There was no difference in MAO activity between patients and normals, although it was lower in borderline patients. MAO activity was inversely correlated with sensation seeking, especially in the patient group, as predicted. The results are consistent with the view that platelet MAO activity is a marker of general psychopathology.

Adrenergic status in anxiety disorders: platelet alpha 2-adrenergic receptor binding, blood pressure, pulse, and plasma catecholamines in panic and generalized anxiety disorder patients and in normal subjects

In order to evaluate adrenergic function in anxiety disorders, platelet alpha 2-adrenergic binding parameters and supine and standing blood pressure, pulse, and venous plasma epinephrine and norepinephrine were determined in patients with panic attacks or generalized anxiety disorder and in normal subjects. The maximum number of binding sites (Bmax) for the partial agonist tritiated clonidine was significantly lower for both patient groups than for normal subjects, and the Bmax for the antagonist tritiated yohimbine was significantly lower for panic patients. There were no other substantive differences across groups. Prior exposure to psychotropic drugs might account for the results for clonidine binding, but not for yohimbine. The Bmax for clonidine was correlated with norepinephrine increases upon standing and, for panic patients, with the severity of full unexpected panic attacks. These data provide further evidence of adrenergic receptor abnormalities in people with anxiety disorders.

Generalized anxiety disorder: some biochemical aspects

Fifty-one patients who met DSM-III criteria for generalized anxiety disorder, and who were recruited to participate in a drug outcome study, filled out a variety of rating scales and had blood samples drawn for plasma norepinephrine, epinephrine, and free 3-methoxy-4-hydroxyphenylglycol (MHPG) after a 20-min rest period. This group was compared to 15 normal controls who also had their blood drawn after a 20-min rest period. While the two groups were initially found to have significantly different levels of plasma free MHPG through the use of t tests, this finding was not confirmed by subsequent discriminant analysis.

Psychiatric morbidity, platelet monoamine oxidase and tribulin output in headache

A significantly higher proportion of patients with headache showed scores in the psychopathological range of the General Health Questionnaire (GHQ) compared with controls, with ratings particularly high on the anxiety and depression subscales. Across the whole group, there was a significant negative correlation between platelet monoamine oxidase (MAO) activity and GHQ score overall, and with the anxiety and depression subscales. There was a significant positive correlation between platelet MAO activity and urinary output of the endogenous MAO inhibitor, tribulin. Within the migraine group, there was a significant negative correlation between tribulin output and GHQ score. These findings suggest that the biochemical nature of the anxiety associated with migraine may differ from that in other conditions such as generalized anxiety disorder where high platelet MAO activity and high tribulin output have been reported.

Platelet monoamine oxidase in alcoholism

We studied platelet monamine oxidase (MAO) activity using 14C-tyramine as substrate in hospitalized alcoholic patients in the early phases of abstinence and in nonhospitalized normal control volunteers. Platelet MAO was determined in 75 patients (67 men, 8 women) with alcoholism and 123 normal control volunteers (52 men, 71 women). The platelet MAO activity in alcoholic patients was significantly lower than in normal control volunteers. We also observed that the mean platelet MAO activity in male alcoholics was significantly lower than in normal males. The analysis of platelet MAO in alcoholics revealed a mixture of two normal distributions. Alcoholic patients falling into the low MAO component were younger in age, with a lower age of onset of alcoholism, and had higher frequencies of family history of alcoholism. They thus resembled type II alcoholics described by other investigators. Platelet MAO may thus serve as a useful biological marker for subtyping alcoholism and identifying high-risk groups at an early stage. The findings of this study are consistent with previous reports of low platelet MAO activity in alcoholic patients.

Systemic hormonal and physiological abnormalities in anxiety disorders

Among the studies of systemic hormonal and physiological abnormalities associated with anxiety disorders, the most consistent and extensive findings suggest (a) peripheral adrenergic hyperactivity (including increases in norepinephrine but not epinephrine) and functional dysregulation, (b) increased incidence of mitral valve prolapse in panic patients, and (c) normal suppressibility of the hypothalamic-pituitary-adrenal cortical endocrine system with dexamethasone in panic patients. Other less-certain findings include (a) increased circulating concentrations of plasma ACTH and/or cortisol, and prolactin, in panic patients, (b) increased platelet monoamine oxidase activity in generalized anxiety and/or panic patients, (c) decreased gonadal axis activity in some anxious individuals, (d) decreased nighttime melatonin plasma concentrations in panic patients, and (e) peripheral alpha 2 and beta-adrenoreceptor down-regulation, with normal serotonin binding parameters. These findings, taken together, provide tentative support for dysfunction in adrenergic and GABAergic central nervous system mechanisms in people with anxiety disorders. Abnormal anxiety and normal stress both show evidence of adrenergic hyperactivity; however, there appear to be differences in hormonal profiles, especially the apparent lack of increase of epinephrine during panic attacks, as well as differences in the reactivity of the system, and in the "trigger" mechanisms which determine when the response occurs.

Does heart rate differentiate neurotic from normal people in a conditional reflex test?

This study is to compare heart reactivity between normals and anxiety neurotic patients. Five male and five female patients with anxiety neurosis and four male and five female normal persons were submitted to classic delayed conditional reflexes with different probabilities of reinforcement (shock), to a defensive instrumental conditional reflex, and to a neutral nonreinforced stimulus. The basal heart frequency was higher in neurotics and in women than in normals and men. The conditional stimulus (CS) associated with a shock generally produced a bradycardia in normal individuals and in neurotic men, but a tachycardia in neurotic women (effects most pronounced in cases with 100% shock probability). The instrumental CS caused a tachycardia in all of the groups, with highest values in neurotic women. The neutral stimulus produced bradycardia in all persons. The aftereffect of the light stimulus depended on whether a shock was administered and on the CS. The differences between neurotics and normals are explained as caused by the heightened excitatory level of the CNS of the neurotic group, produced by the unspecific activating effect of chronic anxiety, and differences of plastic processes in both groups, resulting in different effects of phasic anxiety on the heart. Complex inhibitory-excitatory interactions of the sympathetic and the vagal system underlying the heart rate changes may be assumed. Possible mechanisms leading to sex differences are discussed.

Frontal midline theta activity and platelet MAO in human subjects

The distinctive theta rhythm that appears at the frontal midline during the performance of mental tasks has been designated as frontal midline theta (Fm theta). Fm theta shows individual differences and seems to be related to certain personality traits. In several studies, it has been indicated that low platelet monoamine oxidase (MAO) activity is also associated with certain personality traits. In the present study, we found a negative correlation between the appearance of Fm theta and platelet MAO activity. Subjects with marked extroversion show a high amount of Fm theta and low MAO activity. It is therefore suggested that Fm theta, an electrophysiological marker, may be useful in the investigation of monoamine functions in the central nervous system (CNS) by way of platelet MAO activity, a biochemical marker.

Platelet monoamine oxidase activity in panic disorder

Platelet monoamine oxidase (MAO) activity was studied in 21 patients meeting Research Diagnostic Criteria for panic disorder and in 12 healthy controls. Platelet MAO activity in females in both patient and control groups tended to be higher than that in males, but the results did not reach statistical significance. Platelet MAO activity was significantly decreased in panic disorder patients compared to controls.

Platelet [3H]imipramine binding in generalized anxiety disorder, panic disorder, and agoraphobia with panic attacks

The density of platelet [3H]imipramine binding sites is reported to be decreased in unipolar depression and, hence, is a putative biological marker. There is considerable evidence for a phenomenological and biological relationship of panic disorder with affective disorder. We studied platelet [3H]imipramine binding site density in unmedicated subjects with generalized anxiety disorder (GAD; n = 55), panic disorder (PD) with and without agoraphobia (n = 52), and normal controls (n = 26) in order to determine whether or not patients with panic disorder differed from controls in this biological assay. We found no differences in binding site density (Bmax) or affinity (Kd) among the PD, PD with agoraphobia, GAD, and control groups. Nor did we find a relationship between Bmax or Kd and the severity of depressive symptoms or the presence of a family history of affective disorder. In view of two conflicting prior studies, the use of [3H]imipramine binding in panic disorder remains problematic.

Relationship of platelet MAO activity to characteristics of major depressive illness

Sixty-seven patients (greater than or equal to 55 years of age) with major depressive disorder had pretreatment assays of platelet monoamine oxidase (MAO) activity. As in previous studies, women had higher MAO activity than men, and MAO activity was positively correlated with age. Patients with melancholia (DSM-III) had significantly higher MAO activity than those without melancholia. This finding may reflect the higher MAO activity associated with the symptoms of anhedonia and mood autonomy. Anxiety also was correlated with higher MAO activity, as was a positive family history of depression. In addition, postdexamethasone cortisol levels were correlated with platelet MAO activity.

Platelet monoamine oxidase activity in patients with panic disorder

Preliminary reports have indicated that platelet monoamine oxidase (MAO) activity is elevated in patients with anxiety disorder. We compared MAO activity in 20 drug-free patients with panic disorder with 20 age- and sex-matched normal controls. MAO activity in patients was significantly higher than in normals. MAO activity was not correlated with age or plasma catecholamine levels. The authors speculate about the possible significance of elevated MAO activity in patients with panic disorder.

Platelet monoamine oxidase activity in schizophrenia: relationship to family history of the illness and neuroleptic treatment

Platelet monoamine oxidase (MAO) activity was determined in a large population of drug-free and haloperidol-treated schizophrenic patients and healthy controls and, in a second study, in a sample of schizophrenics after a wash-out period and at different times during treatment with haloperidol. Enzyme activity was significantly decreased in both acute and chronic haloperidol-treated schizophrenics, but not in drug-free schizophrenics, compared with normal controls. No significant difference was observed between drug-free schizophrenics with a family history of the illness and those without such history, and between healthy relatives of schizophrenic patients and normal controls without a family history of schizophrenia. MAO activity was significantly reduced after 14 and 21 days of haloperidol treatment, and such reduction did not correlate with response to treatment. These data strongly support the idea that neuroleptic intake may, at least in part, explain low MAO values repeatedly reported in schizophrenics.

Kinetic evaluation of platelet monoamine oxidase following relaxation in chronic anxiety

The effect of relaxation training, utilizing EMG biofeedback, on platelet monoamine oxidase (MAO) activity was examined in patients with a history of chronic anxiety. Anxiety scores and MAO activity were significantly lowered after 4 weeks of therapy. Kinetic studies, using phenylethylamine as substrate, indicated a significant increase of the Km constant while the Vmax showed no significant or consistent variation. It is thought that this phenomenon represents an adaptive response by the individual to maintain a homeostatic level of the biogenic amines.

Platelet monoamine oxidase activity and trace acid levels in plasma of agoraphobic patients

Platelet monoamine oxidase activity and plasma trace acid levels in 29 patients classified as agoraphobics was estimated. MAO activity towards p-tyramine and beta-phenylethylamine was found to be significantly higher in agoraphobics than in non-agoraphobic depressed patients and healthy controls. In addition plasma p-hydroxyphenylacetic acid levels were low in both agoraphobic and depressed patient groups. All patients were also assessed by Spielberger State Anxiety and the short form of the Beck Depression Inventory scales. No significant correlations could be found between platelet MAO activity or plasma trace acid levels and the psychological scores.

Catecholamines and anxiety

Plasma catecholamines and heart rate were determined in drug-free groups of anxious patients and normal controls before and 20 min after intramuscular injection of 0.01 mg/kg of 1/1000 diluted epinephrine. Levels of anxiety after the injection were determined via the State Anxiety Scale of State Trait Anxiety Inventory. Both groups showed substantial increases in plasma levels of epinephrine and norepinephrine and heart rate after the injection. However, there were no significant differences between anxious patients and controls on plasma catecholamines and heart rate before or after the injection and post injection levels of State Anxiety. The anxious subjects showed a significant correlation between post injection heart rate and State Anxiety.

Comparison of biochemical properties of platelet monoamine oxidase in mentally disordered and healthy individuals

We have investigated some biochemical properties of platelet monoamine oxidase (MAO) isolated from chronic schizophrenic and agoraphobic patients, nonschizophrenic institutional controls, and healthy volunteers. The enzyme activity level in the healthy population was reasonably constant over at least a 6-week period. High correlations were found between MAO activity assessed for different substrates (p-tyramine, beta-phenylethylamine, and tryptamine). Some heterogeneity of the platelet MAO may exist, however, at least in some of the chronic schizophrenics, since the substrate specificities were changed and the Km values reduced. The half-life of the enzyme at 58 degrees C was 2-3 minutes and the transition temperature derived from Arrhenius plots was 16-17 degrees C with respect to beta-phenylethylamine. Platelet MAO from chronic schizophrenics was not significantly different from control values with respect to temperature effects. SDS-polyacrylamide gel electrophoresis of the 3H-pargyline-MAO adduct revealed that the subunit of platelet MAO is a single band protein with a molar individuals. The adjacent structure of the flavine site of the platelet MAO was chromatographically identical to the penta-peptide isolated from MAOs from other tissues. The response of platelet MAO to thimerosal, a new differential type A MAO inhibitor, could be distinguished not only from type A MAO isolated from human placenta, but also from type B MAO isolated from bovine liver.