The relationship between anxiety and the level of peripheral vasomotor activity; an experimental study

Drug Addiction and Habit Formation—An Attempted Integration

In view of the promise attached to the recent attempts to integrate learning and personality theory (Eysenck, 1957), and the suggestion that drug addiction might be a learned response, it would appear profitable to consider the relevance of this integration to a better understanding of addiction, a suggestion reinforced by two recent papers by Partridge (1959a, b). On the basis of a clinical survey of addiction he came to the conclusion that the extent and severity of addiction was dependent on “… the extent to which the particular personality can tolerate them (i.e. the symptoms, such as anxiety, which would arise without the drug) … patients with a low tolerance of discomforts and frustrations are those more likely to be addicts, just as they are more likely to turn to drugs in the first place … the development of addiction, in fact, depends much on the personality … the form of addiction depends more on the circumstances and opportunities with which the particular personality has been confronted.” Such considerations and conclusions can be conceptualized within and predicted from the theoretical framework to be proposed later in the present review.

Atypical antipsychotics cause an acute increase in cutaneous hand blood flow in patients with schizophrenia and schizoaffective disorder

OBJECTIVE

Clinical studies suggest resting thermoregulatory cutaneous vasomotor tone could be increased in schizophrenia, resulting in reduced hand blood flow. In animal models, atypical antipsychotics including clozapine potently inhibit sympathetic neural outflow to the thermoregulatory cutaneous vascular beds. We have now determined whether antipsychotic medication administration is associated with an acute increase in hand blood flow in patients with schizophrenia and schizoaffective disorder, and whether this increase correlates with clinical status.

METHOD

Hand temperature was measured with an infrared camera in 12 patients with chronic schizophrenia or schizoaffective disorder 30 min prior to, then 30 and 60 min following medication. Clinical status was assessed via the Brief Psychiatric Rating Scale (BPRS). Results were compared using regression and repeated measures analysis of variance.

RESULTS

A robust and significant increase in hand temperature (p < 0.001) was observed following antipsychotic administration. The mean increase after 60 min was 4.1 ± 2.4°C. This increase was significantly associated with colder hand temperature prior to medication (p < 0.05; suggestive of increased resting vasoconstriction) and with more severe psychiatric symptoms (p < 0.05).

CONCLUSIONS

Atypical antipsychotics were associated with increased hand blood flow, consistent with inhibition of thermoregulatory sympathetic outflow to the cutaneous vascular bed in patients with schizophrenia and schizoaffective disorder. This increase correlated with symptom severity. Hand temperature increase following antipsychotic medication may therefore be a simple and informative physiological marker of disease activity and potential response in patients with schizophreniform disorders. Given that antipsychotics also inhibit sympathetic outflow to brown adipose tissue, which normally converts energy to heat, future studies should examine whether antipsychotic-induced hand temperature increase is associated with antipsychotic-induced weight gain.

Clozapine and olanzapine, but not haloperidol, reverse cold-induced and lipopolysaccharide-induced cutaneous vasoconstriction

RATIONALE

Reduction of body temperature is used as predictor of psychotropic drug action. The cutaneous circulation functions as a heat-loss component of temperature regulation. Clozapine and olanzapine reverse hyperthermia and sympathetically-mediated cutaneous vasoconstriction induced by MDMA (3,4-methylenedioxymethamphetamine, ecstasy), suggesting that these drugs might reverse other forms of sympathetically mediated cutaneous vasoconstriction.

OBJECTIVES

Clozapine and olanzapine were compared with haloperidol with respect to their ability to reverse cold-induced and LPS (lipopolysaccharide)-induced cutaneous vasoconstriction in rabbits.

METHODS

Cutaneous blood flow was measured in conscious rabbits by Doppler ultrasonic flow probe implanted around the central ear artery, and body temperature was measured telemetrically. After control observations, animals were transferred from 26 to 10 degrees C, or LPS (0.5 microLg/kg IV) was administered. After 30 min, clozapine, olanzapine or haloperidol was administered and ear pinna blood flow and body temperature were measured for another 30 min.

RESULTS

Clozapine, in a dose responsive manner (1, 2.5 and 5 mg/kg IV), substantially reversed cold-induced ear pinna vasoconstriction and reduced body temperature. Clozapine (1 mg/kg IV) reversed LPS-induced cutaneous vasoconstriction and reduced the LPS-induced rise in body temperature. Olanzapine had generally similar effects. Haloperidol (1 mg/kg IV in cold experiments and 0.2 mg/kg IV in LPS experiments) did not reverse ear pinna vasoconstriction, or affect body temperature.

CONCLUSIONS

Both clozapine and olanzapine, but not haloperidol, reverse physiologically induced cutaneous sympathetic vasomotor discharge. Because of the close link between psychological function and sympathetic regulation of cutaneous blood flow, similar neuropharmacological mechanisms might underly the cutaneous vasodilating action and the psychotropic actions of atypical antipsychotic drugs.

CRF1-receptor antagonist CP-154526 reduces alerting-related cutaneous vasoconstriction in conscious rabbits

Cutaneous vasoconstrictor responses elicited by salient stimuli in conscious rabbits may be a sensitive physiological index of emotional arousal/anxiety. Ear-pinna blood flow was measured by preimplanted laser Doppler probes, and animals were exposed to situations involving different types of potentially salient stimuli before and after i.v. administration of CP-154526 (15 mg/kg) or diazepam (4 mg/kg). At rest, ear-pinna blood flow was stable (coefficient of varition=11+/-2) and remained at high level 93+/-13% of test time. Exposure to novel environment elicited flow fluctuations (coefficient of variation=79+/-8) and reduced amount of time spent at high level to 25+/-6%. Defined unconditioned stimuli caused rapid falls in ear-pinna flow, with nociceptive stimulation producing more vigorous and consistent effects (flow response index 0.66+/-0.02) compared with non-nociceptive (flow response index 0.49+/-0.04). CP-154526 slightly raised mean arterial pressure (from 81+/-2 to 93+/-3 mmHg), increased heart rate (from 198+/-1 to 220+/-4 beats/min) and produced a mild vasoconstriction in the ear-pinna bed (flow fell from 46+/-10 to 25+/-6 cm/s). CP-154526 substantially reduced cutaneous vasoconstrictor responses elicited by the exposure to novel environment and by defined non-nociceptive stimuli, with flow-response index fall from 0.53+/-0.10 to 0.17+/-0.09 and from 0.47+/-0.04 to 0.24+/-0.04, respectively, without affecting responses to nociceptive stimuli. Diazepam reduced only vasoconstrictor responses elicited by the exposure to novel environment, with flow-response index fall from 0.40+/-0.12 to 0.27+/-0.07. Sensitivity of rapid changes in rabbit ear-pinna blood flow to anxiolytic drugs supports the idea that increased cutaneous vascular tone reflects enhanced arousal in rabbits.

Raphe region mediates changes in cutaneous vascular tone elicited by stimulation of amygdala and hypothalamus in rabbits

Raphe pallidus/parapyramidal neurons control cutaneous vasoconstriction induced by noxious stimuli. To determine whether they mediate forebrain-induced cutaneous vasoconstriction, we assessed changes in ear pinna blood flow elicited by electrical stimulation of amygdala and hypothalamus before and after injection of muscimol into the raphe/parapyramidal region. We compared ear flow with simultaneously recorded mesenteric flow. Experiments were performed in rabbits anesthetized with urethane (1.25-1.5 g/kg), paralysed and mechanically ventilated. Amygdala stimulation reduced skin conductance from 0.32+/-0.06 to 0.10+/-0.02 cm/s per mmHg (P<0.05, n=9), without effect on mesenteric conductance. Hypothalamic stimulation caused vasoconstriction in both cutaneous and mesenteric beds (conductances fell from 0.27+/-0.05 to 0.05+/-0.02 cm/s per mmHg and from 0.27+/-0.06 to 0.14+/-0.04 cm/s per mmHg (P<0.05, n=9), respectively). Muscimol microinjection (5 nmol in 100 nl) to raphe/parapyramidal region eliminated amygdala- and hypothalamus-induced skin vasoconstriction (pre-stimulus conductance 0.42+/-0.13 and 0.41+/-0.11 cm/s per mmHg, post-stimulus 0.41+/-0.12 and 0.39+/-0.10 cm/s per mmHg, respectively), but not hypothalamically-induced mesenteric vasoconstriction (pre-stimulus 0.29+/-0.06, post-stimulus 0.16+/-0.03 cm/s per mmHg, P<0.05, n=8). The latter was strongly attenuated by bilateral injection of muscimol to the rostral ventrolateral medulla. Data suggest that descending hypothalamo-spinal and amygdala-spinal pathways constricting the cutaneous vascular bed relay in the raphe/parapyramidal area. A relay in the rostral ventrolateral medulla contributes substantially to mesenteric vasoconstriction elicited from the hypothalamus.

Autonomic instability during relaxation in panic disorder

The ability to relax was assessed in 14 patients with panic disorder (PD) and 15 non-anxious control subjects for 10 min. Before and after relaxation, subjects performed a standardized activating task of talking continuously for 4 min. The fractional decline in reported anxiety, tension, and alertness between the first talking period and the relaxation minimum did not differ between groups, although absolute levels of anxiety and tension were higher for PD patients. The fractional decline in skin conductance between the first talking period and the last minute of relaxation was less for PD patients than control subjects, while their increase in skin temperature was greater. Skin conductance showed a linear decline over the logarithm of relaxation time, the slope of which was less steep for PD patients. Goodness of fit of skin conductance over log time was also significantly poorer for PD patients. Heart rate levels or slopes did not differ between groups. Autonomic differences between PD and control subjects were largely due to six patients who reported having panic attacks during the test and higher pretest anxiety levels. In conclusion, indicators of relaxation were inconsistent. Skin conductance suggested autonomic instability during quiet sitting in patients who panic or who are prone to panic.

Cardiac vagal tone in generalised anxiety disorder

The aim of the present study was twofold: firstly, to determine cardiac vagal tone in subjects with generalised anxiety disorder directly, using an invasive pharmacological method; and secondly, to test whether the non-invasive method of measuring the amplitude of respiratory sinus arrhythmia (RSA) gives a reliable estimate of cardiac vagal tone in this form of anxiety disorder. Comparison of baseline physiological measures of anxious and control subjects revealed that cardiac vagal tone and heart rate were not different in the two groups of subjects, whereas length of the respiratory cycle and amplitude of respiratory sinus arrhythmia were reduced in the former group. Because of the higher respiratory rates of anxious subjects, the RSA method was found to underestimate cardiac vagal tone in generalised anxiety disorder.

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.

Validation of the Holtzman anxiety scale by vasomotor biofeedback

The Holtzman Inkblot Technique (HIT) and the State-Trait Anxiety Inventory were administered to 81 undergraduates who later received biofeedback training for increases in index finger skin temperature. The Holtzman anxiety measure correlated significantly with voluntary temperature increase and the High Anxiety Group, identified by the HIT, was able to achieve significant increases in digital temperature. No significant relationships were found between State-Trait Anxiety measures and either Holtzman anxiety scores or vasomotor control, nor were there significant increases in temperature among State-Trait anxiety groups. The results supported the validity of the HIT as a measure of anxiety, but failed to characterize this anxiety as either state or trait in nature.

Differential effects on test stress on the heart rates of extraverts and introverts

A mental arithmetic task was administered to 39 subjects under conditions which imposed social stress. Using the relaxed state to provide a baseline, changes in heart rate and finger blood volume pulse were recorded. The subjects were divided to obtain groups with extreme scores on Eysenck's PEN scales, and the groups were compared on the two psychophysiological measures. Contrary to Eysenck's theory of Autonomic Lability as the neurological basis of N, the high N scoring group was not differentiated from the low N group by change in level of sympathetic activity as indicated by blood volume pulse, while, on the heart-rate measure, introverts showed a large increase and extraverts considerably less: there was no overlap between groups (p less than 0.001). It was concluded that extraverts exhibit greater parasympathetic activity relative to sympathetic arousal under this stress condition.

Disturbances in the regulation of body temperature in anorexia nervosa

The regulation of body temperature was investigated in 11 patients with anorexia nervosa, initially while they were in a malnourished state and again after refeeding when they had reached a near normal weight. The results suggest that there may be a primary defect of temperature regulation in anorexia nervosa which is linked in some way with the feeding disorder characteristic of this illness.

The relationship between clinical diagnosis and anxiety, assessed by forearm blood flow and other measurements

Anxiety may be present to a greater or lesser degree in almost every psychiatric syndrome. The ability to quantify the degree of anxiety present in an individual patient has important implications for diagnosis, treatment and prognosis. Accurate clinical assessment of anxiety is by no means an easy task, although many psychiatrists believe it to be. If no other methods are used, there is no way of knowing how often an individual clinician is right or wrong. However, if several independent methods of assessing anxiety are used, more data are available, and a better overall judgment on an individual patient can be made.

REFLEX VASOMOTOR ABNORMALITIES IN THE HANDS OF MIGRAINOUS SUBJECTS

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