Hypercortisolemia decreases dexamethasone half-life in rabbit.

The pharmacokinetics of dexamethasone have been found to be related to endogenous hypothalamic-pituitary-adrenal (HPA) axis activity. Lower plasma dexamethasone levels in psychiatric patients (especially depressed) who are dexamethasone suppression test (DST) nonsuppressors have previously been reported. Since DST nonsuppression is one measure of HPA axis hyperactivity and is usually associated with relatively increased plasma cortisol levels and lower post dose plasma dexamethasone levels, we hypothesized that hypercortisolemia can induce a more rapid disappearance of dexamethasone from plasma. We therefore studied the kinetics of dexamethasone in rabbits before and after a period of sustained hypercortisolemia produced by administration of IM hydrocortisone acetate, a slowly absorbed salt of cortisol. Mean dexamethasone half-life decreased significantly from baseline of 1.92 h on day zero in seven rabbits to 1.17 h on experimental day 17 of induced hypercortisolemia (P < 0.001), while there was no significant change in saline treated controls (n = 3). Dexamethasone half-life had returned to the baseline levels when retested 88 days later on experimental day 105. The results indicate that pronounced hypercortisolemia decreases dexamethasone half-life in rabbits, and support the concept that increased circulating cortisol levels induce hepatic enzymes that metabolize dexamethasone. Thus, the lower postdexamethasone plasma dexamethasone levels and decreased dexamethasone half-life in DST nonsuppressors may in part reflect the effect of prior or coincident hypercortisolemia.

Lithium isotopes: differential effects on renal function and histology.

OBJECTIVES: Reduction in renal concentrating ability has been reported in patients undergoing chronic lithium treatment. Prior work has demonstrated differences in physiological effects of the stable lithium isotopes, 6Li and 7Li. Here, we measured the degree of polyuria, polydipsia and kidney histological changes induced in rats by equimolar amounts of 6LiCl, 7LiCl and the commercially available mixture of both isotopes. METHODS: Rats were given 1.0 mEq/kg of either 6LiCl, 7LiCl or 'nLiCl' (isotope mixture, 93% 7LiCl) by subcutaneous injection twice daily for up to 49 days. Twenty-four-hour urine volume and water intake were measured daily. Kidneys from rats treated for 7 days with 1.5 mEq/kg 6LiCl, 7LiCl and vehicle were examined under light microscopy and histopathologic changes graded on a 4-point scale of severity. RESULTS: All rats showed loss in renal concentrating ability manifested by increasing urine volume and water intake. Peak effects occurred after 9-13 days treatment, then declined to stable levels at two to three times pre-treatment level. Mean peak effect was significantly greater for 6LiCl than for 7LiCl. Chronic effects of 6LiCl (weeks 3-7 of treatment) on polyuria and polydipsia were persistently higher than that of 7LiCl. nLiCl effect was intermediate. Kidneys from rats treated for 7 days with 6LiCl showed more frequently severe lesions in renal tubules than did 7LiCl-treated rats. CONCLUSIONS: Our current data and prior studies suggest that elimination or reduction of 6Li from pharmaceutical preparations may merit further evaluation as a possibly less potentially nephrotoxic form of lithium treatment.

Psychomotor performance and monoamine function in bipolar and unipolar affective disorders.

BACKGROUND: Affective disorders are associated with prominent psychomotor abnormalities that may be related to changes in arousal or motivation due to altered catecholamine function. METHODS: We investigated relationships between performance on psychomotor tests of motor speed (reaction time and tapping speed) and visual tracking (trail making and dot placement) and catecholamine system function including cerebrospinal fluid (CSF) or urinary concentrations of catecholamines or their metabolites. Subjects were medicine-free inpatients with unipolar depression or with manic, depressive, or mixed episodes of bipolar disorder, and healthy controls matched by gender and stratified by age. RESULTS: Unipolar and bipolar depressed patients were impaired in motor speed, dexterity, and visual tracking, whereas manic and mixed patients did not differ from controls. Tapping speed correlated positively with CSF 3-methoxy-4-hydroxyphenylglycol in healthy controls and with CSF homovanillic acid in bipolar depressed subjects. Increased catecholamine function correlated with slowing in all other measures for patients with bipolar disorder. Relationships between catecholamines and psychomotor function were weaker in unipolar depressed subjects. Psychomotor function was related to severity of depression in bipolar, but not in unipolar, patients. CONCLUSIONS: These data suggest that catecholamine systems are associated with increased arousal and psychomotor impairment in patients with bipolar disorder. Similar behavioral changes have different neurotransmitter relationships in unipolar disorder.

Direct comparison of two widely used activity recorders.

Wrist actigraphy is increasingly used to track circadian rest-activity cycles and to identify states of wakefulness and sleep, yet the measurement characteristics of activity recorders have never been compared. Two widely used recorders are compared here: the MotionLogger from Ambulatory Monitoring, Inc (AM) and the Gaehwiler (G). They were worn together on the same wrist for periods averaging 41.5 hours by five members of a research team. Activity counts were stored every half-minute. Pairwise comparisons between recorders of each type showed both types to be reliable. Each also validly detected circadian rest/activity cycles. Both types suffered, however, from insensitivity. For the lower 75% of activity levels, the variance of data from the G was indeed so small as to be essentially uninformative. Since these levels include over 95% of all nocturnal data, the G must be less sensitive than the AM to small nocturnal movements, including those signifying arousal. An additional difference is that data from the AM but not the G were distributed in biphasic fashion. Biphasic activity levels are consistent with the common assumption that activity/wakefulness and rest/sleep are distinct neurobehavioral states. As the use of actigraphy increases, the important differences found here between two leading instruments point to an urgent need for standards by which activity recorders can be compared. Aspects of instrument design that could be quantitatively rated are reliability, validity, ruggedness and artifact rejection.

Risks and benefits of selective serotonin reuptake inhibitors in the treatment of depression.

Depression is a common, life-disrupting, potentially lethal illness that can affect both sexes and all ages. Its peak onset is in the early adult years. It is more common than hypertension in primary care practice. Recent studies show that fewer than 1 in 20 depressed patients are correctly diagnosed and adequately treated. Depression periodically destroys the productivity of those with the condition, and depressed patients have a worse quality of life than patients with debilitating, chronic conditions such as arthritis, hypertension, diabetes mellitus and back pain. Suicide occurs in as many as 15% of patients with depression, especially those with recurrent episodes and hospitalisations, and may even occur in those with in subsyndromal depression. Suicide is one of the leading causes of death, and individuals who complete suicide have usually experienced mood disorders, mainly depression. Current data support a decreased frequency of suicidal ideation with all antidepressants, including selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs). Modern pharmacotherapy is the cornerstone for effective treatment of depression. As they are well tolerated, even in the presence of comorbid medical illness, and easier to manage, SSRIs enhance compliance. A fully adequate antidepressant dosage is suitable for patients of all ages and can be used by non-psychiatrist physicians for the treatment of the acute episode, as well as the frequent recurrences that often require long term maintenance antidepressant medication. SSRIs have fewer drug interactions than older antidepressants, and even the SSRI inhibition of hepatic cytochrome P450 enzymes has proven only very infrequently to be of clinical importance. SSRIs also effectively treat anxious depression, dysthymia and atypical depression. Fluoxetine may provide more rapid onset of therapeutic effect because it can be started at closer to its usual full therapeutic dosage than other SSRIs or older antidepressants. SSRIs, in particular fluoxetine, are more suitable for use as long-term maintenance therapy in these chronic relapsing diseases. These factors and the high efficacy rate, increased safety in overdose, reduced incidence of adverse effects (mostly decreasing with time) and superiority in ease of maintaining patients in adequate treatment plans provides fluoxetine with an overall superior therapeutic profile.

Classically conditioned changes in plasma cortisol levels induced by dexamethasone in healthy men.

Animal research has indicated that the activity of the hypothalamic-pituitary-adrenal axis can be influenced by classical (Pavlovian) conditioning procedures. To test the hypothesis that alterations in plasma cortisol levels can be conditioned in humans, the present study used a prospective, randomized, double-blind, placebo-controlled design in which a distinctively flavored beverage was paired with p.o. administration of dexamethasone. Twenty-five healthy men were randomly assigned to one of two groups. During the conditioning phase of the study, subjects in the experimental group received three conditioning trials (pairings of a distinctively flavored beverage with a capsule containing 5 mg dexamethasone) separated by 1 wk recovery periods. Subjects in the control group were treated identically, except that the capsule contained a placebo. During the test phase, all subjects underwent a test day (reexposure to the distinctively flavored beverage before receiving a placebo capsule) and a comparison day (no exposure to the beverage or the capsule). Plasma cortisol was assessed repetitively before and after administration of the beverage and capsule, as were possible confounding factors, including: behavioral variables, psychological distress, aversive reactions to the beverage, and expectations of treatment. After reexposure to the beverage and administration of a placebo capsule (conditioned stimuli), the experimental group had significantly higher levels of plasma cortisol than the control group, after controlling for variability in baseline levels of cortisol (F(5,60)=3.09; P=0.015) that could not be explained by differences in other study variables. No differences in cortisol levels were found on the comparison day. These results support the study hypothesis that changes in plasma cortisol levels can be classically conditioned in humans by pairing a distinctive beverage with p.o. administration of dexamethasone.

Subsensitivity of adenylyl cyclase-coupled receptors on mononuclear leukocytes from drug-free inpatients with a major depressive episode.

Previous studies have demonstrated blunted beta-adrenergic responsivity in leukocytes from depressed patients. We sought to determine if this blunted cyclic adenosine monophosphate (AMP) response is specific for beta-adrenergic receptors (homologous), or whether other adenylyl cyclase-coupled receptors are also involved (heterologous), in order to localize this effect at the level of the receptor versus the coupling protein or the transducer, adenylyl cyclase. We studied adenylyl cyclase-mediated responses in peripheral blood mononuclear cells from 95 drug-free patients with a major depressive episode and 69 healthy controls. We found a similar degree of decrease in the peak cyclic AMP response to activation of the beta-adrenergic receptor (28%) and the prostaglandin receptor (34%) in the depressed patients, which indicated heterologous desensitization. Forskolin cyclic AMP responses were not blunted. Blunting of cyclic AMP responses to isoproterenol did not appear to correlate with levels of plasma norepinephrine and epinephrine or hypothalamic-pituitary-adrenocortical function. The absence of a decrease in the peak forskolin-generated cyclic AMP response, which involves direct activation of adenylyl cyclase, suggests an abnormality at the level of the coupling protein in these adenylyl-coupled receptors in depressed patients. Future studies need to determine whether this leukocyte signal transduction defect in depression also involves brain adenylyl cyclase-coupled receptors.

Circadian rest-activity rhythms in demented and nondemented older community residents and their caregivers.

OBJECTIVE: Disruptive nocturnal behaviors (DNBs) of older people often threaten the caregiving arrangements on which their community tenure depends. Dementing disorders are especially prone to result in disrupted sleep and agitated behaviors ("sundowning"). The objective here was to develop an objective correlate of DNBs, by which their severity and effects on caregivers can be measured. DESIGN: Quantitative comparison of subjective sleep and motor activity patterns in older people and their caregivers. It was hypothesized that older people with reported DNBs would be more motorically active at night than their caregivers. SETTING: Subjects' homes. PARTICIPANTS: Twenty-five demented and 18 nondemented older day-care participants and their paired caregivers. MEASUREMENTS: Older subjects and caregivers simultaneously kept daily sleep logs and recorded wrist motor activity every .5 minute for 9 days. A novel method was devised to identify and exclude from analysis periods when the activity monitor was not being worn. Such periods were common. Activity data were analyzed by computing hourly means and by fitting cosine models by least squares. RESULTS: Demented older people were not significantly more active at night than their caregivers, though group differences varied by time of night. They were significantly less active in the daytime than were their caregivers. Nondemented older people were significantly more active at night than their caregivers and were as active by day as their caregivers. The caregivers of demented and nondemented older people had similar rest-activity patterns. The mean amplitudes of cosine models were smaller in the older adults. Acrophases (peaks) fell between 2 and 3 pm and did not differ significantly among the groups. CONCLUSIONS: As a result of increased nighttime motor activity and decreased daytime activity, rest-activity rhythms were flatter in older adults than in caregivers. This was not explained fully by age and does not necessarily imply that the output of a circadian pacemaker was low. Decreased daytime activity may have resulted from deficient physical stimulation or frailty. Frailty may also explain why nighttime activity was not more elevated in the demented older people. Increased nighttime activity is probably explained by depression, sleep-schedule disturbances, restless legs, or other sleep disorders. Judging by their shared variations of activity, caregivers interacted mainly with the demented older people at bedtime and at rising time in the morning.

Fluoxetine tenth anniversary update: the progress continues.

This tenth anniversary review/update of fluoxetine concentrates on the past 5 years of its clinical application. The mechanism of action of fluoxetine; its metabolism; its efficacy in patients with various diagnostic subgroups of depression, patients with coincident medical disease, children and adolescents with depression, patients with eating disorders, and patients with obsessive-compulsive disorder (OCD); its long-term (maintenance) efficacy; its side effects and toxicity; and pharmacoeconomic considerations are reviewed. Pharmacotherapy is currently the only proven method for treating major depressive disorder that is applicable to all levels of severity of major depressive illness. Since its introduction 10 years ago, fluoxetine has been available to psychiatrists, primary care physicians, and other nonpsychiatric physicians as full-dose effective pharmacotherapy for patients with depression. Fluoxetine has been widely prescribed by physicians knowledgeable in pharmacology and in the treatment of depression because of its proven efficacy (ie, equal to that of tricyclic antidepressants [TCAs]), its ease of administration (with full therapeutic dosing usually starting from day 1), its generally benign side-effect profile, its remarkable safety in over-dose, and its proven effectiveness in the most common depressed patient population--anxious, agitated, depressed patients--as well as in patients with various subtypes and severities of depression. In more recent years it has also proved effective in the treatment of bulimia, an entity for which only limited or inadequate treatment options had been previously available. In OCD, fluoxetine, with its more acceptable side-effect profile and greater ease of dosing, presents a favorable alternative to previous drug therapy and is useful in treating both obsessions and compulsions. Fluoxetine is currently recognized among clinicians as efficacious in treating anxiety disorders and is being used successfully in special depressed populations such as patients with medical comorbidity, elderly patients, adolescents, and children. Rapid discontinuation or missed doses of short-half-life selective serotonin reuptake inhibitors, TCAs, and heterocyclic antidepressants are associated with withdrawal symptoms of a somatic and psychological nature, which cannot only be disruptive, but can also be suggestive of relapse or recurrence of depression. In striking contrast to these short-half-life antidepressants, fluoxetine is rarely associated with such sequelae on sudden discontinuation or missed doses. This preventive effect against withdrawal symptoms on discontinuation of fluoxetine is attributed to the unique extended half-life of this antidepressant. Current studies show that the overall increased effectiveness of fluoxetine in treating depression compensates for its higher cost, compared with older drugs, by reducing the need for physician contact because of increased compliance and less need of titration, and by reducing premature patient discontinuation, thereby yielding fewer relapses, less recurrence, and less reutilization of mental health services.

Nocturnal interactions between community elders and caregivers, as measured by cross-correlation of their motor activity.

As the U.S. population ages, families must assume increasing responsibility for the care of elderly members. Disruptive nocturnal behaviors (DNBs) of elders, such as complaining and demanding help, may result in interactions with caregivers that threaten such arrangements. This study aimed to quantify such interactions by cross-correlating motor activity that was simultaneously recorded from the elders and caregivers. Forty-four elder-caregiver pairs reporting DNBs simultaneously kept sleep logs and wore activity recorders for 6 to 8 days. Day and night activity data were analyzed separately, because circadian variations would otherwise have overshadowed the elder-caregiver covariations of interest. An autoregressive model was fitted to each day and night data segment, and the data-model differences were used to calculate a cross-correlation function. Maximum significant values of the cross-correlation functions (rmax) exceeded .300 in 10 pairs of subjects. The unprocessed motor activity of these pairs looked so similar that rmax was interpreted as a measure of the subjects' interactions. The rmax was significantly larger for nighttime activity, especially in pairs who shared the same bed. It was smaller in pairs whose elders had high depression scores and in those with Parkinson's disease or related disorders. It was not affected by the presence of dementia. Analysis of the lags corresponding to significant values of rmax showed that, in cohabiting pairs, it was mainly the elders who initiated interactions. The findings provide unique, objective evidence that the night is a time of special difficulty for many caregivers of older Americans.

Relationship of 24-hour urinary free cortisol to 4-hour salivary morning and afternoon cortisol and cortisone as measured by a time-integrated oral diffusion sink.

The relationship between salivary corticosteroids integrated over 4-hour periods and urinary free cortisol collected over 24 hours was investigated in normal controls. Twenty-one normal volunteers wore "oral diffusion sink" sampling devices in their mouths for two 4-hour periods (08:00-12:00 hours and 13:00-17:00 hours) and on the same day collected a 24-hour urine specimen. Time-integrated salivary corticosteroid concentrations were determined from the sample devices and urinary free cortisol was measured. Salivary corticosteroids were not consistently higher in the morning than in the afternoon period and did not differ between men and women. Urinary free cortisol levels were higher in women. No salivary corticosteroids measure was significantly correlated with urinary free cortisol. We conclude that time-integrated salivary corticosteroids do not reflect urinary free cortisol levels in normal controls.

The potential role of excessive cortisol induced by HPA hyperfunction in the pathogenesis of depression.

Prolonged hypothalamic-pituitary-adrenocortical (HPA) axis overactivity occurs at all levels of this axis during stress in normals and some depressed patients. This can induce enlargement of the pituitary and adrenals. Various reports showed that cortisol can affect mood and behavior, and disrupt memory and recall. The integrity of the hippocampus is essential for memory function and, via the high density of its cortisol receptors, cortisol induced inhibitory feedback to the HPA axis. Animal data suggest that over time aging and stress can permanently downregulate hippocampal cell receptors, produce chronic hippocampal inflammation (astroglial), and kill cells. Cushing's syndrome patients (high cortisol) show diminished hippocampal size and verbal recall inversely related to cortisol levels. All the above is consistent with the 'cascade hypothesis' of cortisol induced hippocampal damage with resultant diminished inhibition to HPA hyperactivity in a circular manner. High cortisol is associated with altered neurotransmitter function, e.g., diminished brain serotonin synthesis, low CSF 5HIAA, and increased noradrenergic activity.

Drug-induced actions on brain neurotransmitter systems and changes in the behaviors and emotions of depressed patients.

Despite cumulative evidence that the tricyclic drugs result in significant changes in the functioning of brain serotonergic (5-HT) and nordrenergic (NE) systems, such changes have not been found to be associated with recovery from depression. Based upon evidence that the 5-HT and NE systems were associated with different emotions, it was hypothesized that changes in these systems were associated with different components of behavior in drug-responsive patients and not with changes in the "whole" disorder. Findings from this multihospital study of 104 unipolar and bipolar depressed patients showed early drug-associated reductions in anxiety and hostility in treatment responders to precede changes in motor retardation and depressed mood. Adopting this approach of looking for relationships between changes in components of major depression and changes in neurotransmitter system function, decreases in 5-HT and NE metabolite concentrations in cerebrospinal fluid (CSF) in patients treated with tricyclics, were found to be correlated with changes in specific behaviors. Results indicated the following: (1) drug-induced changes in the 5-HT system to be associated with mood aspects, notably anxiety, and depressed mood; changes in NE primarily with the psychomotor, secondarily with the mood components of the depressed state; (2) the pattern of relationships between changes in 5-HT and in mood in the unipolar was different than that in the bipolar subtype. The results indicate that in determining the relationships of biochemical changes to behavioral ones, that it is important to take into account the type of depression (bipolar or unipolar), as well as examining individually and over time those components that make up the disorder of depression. These results support evidence that tricyclics have multiple behavioral actions, that response is mediated through changes in specific behaviors and that this approach warrants further application in prospective studies of antidepressant drug mechanisms and their therapeutic actions.

Adrenomedullary function in depressed patients.

In this paper from the Collaborative Depression Study (CDS)--Biological, a set of data analyses are presented which indicate that depressed states and perhaps depressed mood are associated with a greater activation of the adrenomedullary system than the sympathetic nervous system [as measured by norepinephrine (NE) and normetanephrine excretion]. For the most part this finding of predominant activation of the adrenomedullary system is seen in unipolar and not bipolar patients.

Depressive mania versus agitated depression: biogenic amine and hypothalamic-pituitary-adrenocortical function.

The existence of mixed affective states challenges the idea of specific biological abnormalities in depression and mania. We compared biogenic amines and hypothalamic-pituitary-adrenocortical (HPA) function in mixed manic (n = 8), pure manic (n = 11), agitated bipolar depressed (n = 20), and nonagitated bipolar depressed (n = 27) inpatients (Research Diagnostic Criteria). Mixed manics met Research Diagnostic Criteria for primary manic episodes and also met criteria for major depressive episodes except for duration. The norepinephrine metabolite methoxyhydroxy phenthylene glycol (MHPG) was higher in cerebrospinal fluid from mixed manic than from agitated depressed patients, consistent with differences previously reported between the overall samples of depressed and manic patients. Similarly, patients in a mixed state had higher urinary excretion of norepinephrine (NE) and elevated output of NE relative to its metabolites. HPA activity was similar in mixed manic and agitated depressed patients. These data suggest that mixed manics combine certain biological abnormalities considered to be characteristic of mania and of depression.

Current issues in the treatment of major depression.

Major depression is a common psychiatric disorder associated with considerable suffering for individuals and their families. Indeed, the Medical Outcomes Study reported that the degree of physical and social impairment and the use of health care resources among patients with diagnosable depressive disorders is comparable only to that with chronic cardiac disease. In addition, recent studies in the United States and by the Cross-National Collaborative Group suggest that the cumulative lifetime incidence of major depression is increasing, with the more recent birth cohorts at increased risk. Unfortunately, major depression remains an underdiagnosed and undertreated condition. Evidence from the National Institute of Mental Health (NIMH) Collaborative Depression Study suggests that significant numbers of depressed patients receive little or no antidepressant therapy, despite the availability of effective treatments. Data from the NIMH Collaborative Depression Study further indicate that depression is a chronic and recurrent disorder. The diagnosis and treatment of depression in the elderly remain a significant challenge. Concomitant medical illness frequently obscures the diagnosis, and as a result, large numbers of depressed elderly go untreated. Although there is evidence that pharmacotherapy generally is as effective in the elderly as in younger adults, problems with side effects and compliance may limit the usefulness of some agents. Further investigation is needed to evaluate the effectiveness of antidepressant drugs in the very old and in those with concomitant medical illness.

A primary care perspective on management of acute and long-term depression.

Major depressive disorder causing much social and physical dysfunction and risk of suicide is frequently seen in family practice, often presenting with somatic symptoms, sleep problems, or anxiety. Correct diagnosis allows prompt treatment with decreased morbidity and mortality. The new serotonin selective reuptake inhibitors (SSRIs), like fluoxetine, provide the family practitioner with antidepressants that are devoid of the unwanted and sometimes dangerous side effects of the older drugs. The SSRIs have a more benign side effect profile and are much safer in overdose. Patient education is essential regarding the medical nature of this disorder of the nervous system and its effective treatment with pharmacotherapy and need to continue full-dose maintenance therapy for 6 to 9 months after complete remission of the depressive episode to prevent relapse. Recognition of the recurrent nature of this illness is mandatory, and chronic (lifetime) full-dose prophylactic therapy is often necessary. The SSRIs assist in compliance to treatment.

Neuropsychologic effects of lithium discontinuation.

This study investigated the effects of blind lithium discontinuation and resumption on measures of cognition, creativity, and fine motor performance in 46 lithium-maintained euthymic outpatients. Scores on memory measures, tests of tapping speed, and associative productivity all improved significantly during the time off of lithium. In an effort to further explain these results, analyses were undertaken with six possible intervening variables: age, sex, lithium concentration in plasma, thyroid function, duration of lithium maintenance, and depressive symptoms. Significant group and interactive effects are reported and discussed. A multiple regression analysis suggested that lithium has a greater neuropsychologic effect in younger, less-depressed patients having higher lithium concentrations in plasma.