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Biomedical subjects

R W Lam

Publications and source records attributed to R W Lam.

At least 55 records · Page 3Linked to original sources
PubMed1997

Gender differences in the heritability of seasonal mood change.

The study estimated gender differences in the magnitude of genetic and environmental influence in seasonal mood change. The self-report Seasonal Pattern Assessment Questionnaire (SPAQ) was completed by 339 volunteer reared-together twinpairs (187 monozygotic pairs, 152 dizygotic pairs) and analysed using biometric genetic models. The SPAQ yields a global seasonality score (GSS) which is an index of change in sleep patterns, social activities, mood, weight, appetite, and energy level. The GSS was significantly heritable among males and females, estimated to account for 69% and 45% of the total variance, respectively. For the individual symptoms, changes in sleep patterns, social activities, mood, appetite, and energy levels were accounted for primarily by additive genetic effects in both males (median, 45.5%) and females (median, 30.5%). For both sexes, weight changes were not heritable. Sex-by-genotype analyses suggested that the genetic factors influencing female seasonality may not be the same as those influencing male seasonality.

Adolescent↗
PubMed1997

Effects of chronic lithium treatment on retinal electrophysiologic function.

Some hypotheses suggest that lithium produces its therapeutic effect by reducing sensitivity to light at the level of the retina. In humans, acute administration of lithium is associated with a reduction in retinal light sensitivity. To determine whether similar retinal light sensitivity changes occur with chronic use, we studied 24 euthymic bipolar patients on chronic lithium treatment and 21 age- and sex-matched normal comparison subjects using electroretinography (ERG) and electro-oculography (EOG). No significant differences were found in ERG b-wave amplitudes or implicit times, or in EOG ratios, between the two groups. We conclude that chronic lithium use is not associated with differences in retinal light sensitivity when bipolar patients are compared to normal comparison subjects, and that there is no evidence for retinal toxicity with long-term lithium treatment.

Adult↗
PubMed1997

Atypical depressive symptoms in seasonal and non-seasonal mood disorders.

The authors examined the rates of atypical depression and prevalence of specific atypical symptoms in patients with seasonal versus non-seasonal depression. Fifty-three patients with seasonal affective disorder (SAD) were compared to 54 patients with non-seasonal major depressive disorder (MDD) using the atypical depression diagnostic scale (ADDS). SAD patients scored significantly higher than non-seasonal MDD patients in hyperphagia and hypersomnia, and significantly lower in interpersonal sensitivity and other rejection avoidance. There was no difference in the rate of ADDS diagnosis of atypical depression. Differences between atypical depression and SAD suggest that they are separate subtypes of depression with an overlapping symptom picture.

Adolescent↗
PubMed1997

Sumatriptan-induced growth hormone release in patients with major depression, mania, and normal controls.

The purpose of this study was to assess serotonergic function in patients with major depression or mania using sumatriptan, a novel 5-HT1D receptor agonist, as a pharmacological probe in a neuroendocrine challenge paradigm. We studied 18 drug free patients (10 with acute unipolar major depression and 8 with acute mania) who met DSM-IV criteria, and healthy controls. Subjects presented for testing after an overnight fast. After obtaining a blood sample for baseline growth hormone (GH) levels, sumatriptan (6 mg) was given subcutaneously, and further blood samples were collected at half hour intervals for 2 hours. The results showed that GH responses to sumatriptan were blunted in depressed patients but not in manics, compared to healthy controls. There were no differences in basal GH levels between the 3 groups. The results of this study provide further support for the role of serotonergic system in pathophysiology of major depression, but not in mania.

Adult↗
PubMed1997

Effects of divalproex sodium on 5-HT1A receptor function in healthy human males: hypothermic, hormonal, and behavioral responses to ipsapirone.

Hypothermic and hormonal responses to a challenge with a selective 5-HT1A receptor agonist ipsapirone are considered to provide an index of 5-HT1A receptor function in humans. To examine the effects of divalproex sodium (DVP) on 5-HT1A receptor function in humans, we measured the hypothermic, adrenocorticotropic hormone (ACTH) cortisol, and behavioral responses to ipsapirone in 10 healthy male volunteers. After obtaining a blood sample for baseline hormone levels and measuring body temperature, a single dose of 0.3 mg/kg of ipsapirone was given orally to all the subjects and further bloods and temperature reading were obtained at regular intervals for three hours. The ipsapirone challenge tests were repeated after the subjects had been treated with DVP (1000 mg/day) for one week. The results showed that the hypothermia induced by ipsapirone was significantly attenuated by the DVP treatment, whereas the ACTH/cortisol release and the behavioral responses following ipsapirone challenges were not altered. Our findings suggest that DVP may enhance 5-HT neurotransmission in humans via a subsensitization of 5-HT1A autoreceptors but does not appear to affect postsynaptic 5-HT1A receptors.

Adrenocorticotropic Hormone↗
PubMed1997

The relationship between seasonal mood change and personality: more apparent than real?

A number of recent research reports have reported significant relationships between seasonal mood change (seasonality) and personality. However, some of the results are difficult to interpret because of inherent methodological problems, the most important of which is the use of samples drawn from the southern as opposed to the northern hemisphere, where the phenomenon of seasonality may be quite different. The present study examined the relationship between personality and seasonality in a sample from the northern hemisphere (minimum latitude = 49 degrees N). A total of 297 adults drawn from the general population (112 male and 185 female subjects) completed the Seasonal Pattern Assessment Questionnaire, and the results obtained confirmed most of the previously reported relationships and showed that these are reliable across (i) different hemispheres, (ii) different measures of personality and (iii) clinical and general population samples. However, the impact of the relationship seems to be more apparent than real, with personality accounting for just under 15% of the total variance.

Adolescent↗
PubMed1997

Seasonality of symptoms in women with late luteal phase dysphoric disorder.

OBJECTIVE: Both late luteal phase dysphoric disorder (LLPDD) and seasonal affective disorder are cyclical disorders often manifested by "atypical" depressive features. The goal of this study was to determine whether patients with LLPDD demonstrate substantial seasonal variation in symptoms. METHOD: Consecutive female patients attending a subspecialty clinic in a university teaching hospital were assessed by means of DSM-III-R criteria. All subjects completed the Seasonal Pattern Assessment Questionnaire, modified to include items on the seasonality of premenstrual symptoms. The results were compared with those of a group of female nonclinical subjects (N = 50). RESULTS: One hundred patients met the DSM-III-R criteria for LLPDD. Compared to the nonclinical group, the LLPDD patients had a significantly higher mean global seasonality score (an index of seasonality of mood and vegetative symptoms) and a significantly higher rate of seasonal affective disorder (38% versus 8%) as determined by Seasonal Pattern Assessment Questionnaire criteria. Twenty-five percent of the LLPDD group rated their seasonal variation in premenstrual symptoms as marked or severe, while 30% considered seasonal changes in overall symptoms to be a marked or severe problem. CONCLUSIONS: These results suggest that patients with LLPDD have substantial seasonal patterns in mood and premenstrual symptoms. These seasonal patterns have implications for the clinical assessment and treatment of LLPDD. For example, light therapy may be beneficial for women with seasonal worsening of LLPDD.

Adult↗
PubMed1997

L-tryptophan augmentation of light therapy in patients with seasonal affective disorder.

OBJECTIVE: Up to one-third of patients with seasonal affective disorder (SAD) do not have a full response to light therapy. Given the evidence for serotonergic dysregulation in SAD, we examined the possible role of l-tryptophan as an augmentation strategy for nonresponders and partial responders to light therapy. METHOD: Eligible drug-free patients meeting DSM-IV criteria for SAD were treated for 2 weeks using a standard morning light therapy regimen (10,000 lux cool-white fluorescent light for 30 minutes). Partial and nonresponders were treated for 2 weeks with open-label l-tryptophan (1 g 3 times daily) while light therapy was continued. Ratings at baseline and follow-up included the 29-item Structured Interview Guide for the Hamilton Depression Rating Scale, SAD version (SIGH-SAD) and the Clinical Global Impression (CGI) scale. RESULTS: Sixteen patients began the l-tryptophan augmentation phase. Two patients discontinued medications within 3 days because of side effects. In the 14 patients completing treatment, the addition of l-tryptophan resulted in significant reduction of mean depression scores. Nine of 14 patients (64%) showed very good clinical responses to combined treatment and minimal side effects. CONCLUSION: This open-label study suggests that l-tryptophan may be an effective augmentation strategy for those patients with SAD who show limited or poor response to bright ligh therapy. Further placebo-controlled studies are warranted to demonstrate efficacy.

Adult↗
PubMed1996

Major depression, minor depression, and double depression: are they distinct clinical entities?

The clinical concept of "double depression," i.e., the superimposition of a major depressive disorder in a patient with dysthymic disorder, implies that there are at least some differences between dysthymia, major depression, and double depression. However, the relationship between these two syndromes remains unclear. The present study uses genetic methodology to explore any possible relationship between minor depression, double depression, and major depression. From 1988-1990, all consecutive unrelated inpatients and outpatients (index cases) presenting to a university-based mood disorders service had detailed family histories taken, using modification of the "family history method." Diagnoses for index cases and their first-degree relatives were made according to Research Diagnostic Criteria. For all index cases with a diagnosis of minor or intermittent depression, and minor/intermittent depression plus either single or recurrent depression ("double depression"), morbidity risks for mood disorders were calculated for first-degree relatives (parents, siblings, and children) using the maximum likelihood approach. Results showed no significant differences in morbidity risk calculations to first-degree relatives of index cases with minor/intermittent depression, major depression, or double depression. The data from this genetic perspective suggest that single depression, recurrent depression, minor depression, and double depression are indistinguishable.

Depression↗
PubMed1996

Role of serotonin3 receptors in prolactin release induced by electroconvulsive therapy: a study with ondansetron.

The effect of pretreatment with odansetron on prolactin (PRL) release induced by electroconvulsive therapy (ECT) was examined in 16 depressive patients in a double-blind, placebo-controlled crossover study. Ten patients were pretreated with 4 mg and the other six with 8 mg of ondansetron. The order of administration of study medication (ondansetron and placebo) was counterbalanced. The failure of ondansetron to attenuate ECT-induced PRL release suggested that serotonin3 receptors are not involved in mediating this response.

Adult↗
PubMed1996

Effects of rapid tryptophan depletion in patients with seasonal affective disorder in remission after light therapy.

BACKGROUND: Previous studies show that rapid tryptophan depletion reverses the effects of therapy with serotonergic, but not noradrenergic, antidepressant drugs in patients with remitted nonseasonal depression. The objective of this study was to investigate the effects of rapid tryptophan depletion in patients with seasonal affective disorder (SAD) that was in clinical remission after light therapy. METHODS: Patients who met DSM-III-R criteria for recurrent major depressive episodes, seasonal (winter) pattern (equivalent to SAD), were treated with a standard course of light therapy. Ten patients with SAD in clinical remission after light therapy underwent rapid tryptophan depletion in a placebo-controlled, double-blind crossover study. Behavioral ratings and plasma tryptophan levels were obtained before and after rapid tryptophan depletion. RESULTS: Plasma total and free tryptophan levels were significantly reduced to 20% of normal levels by the rapid tryptophan depletion. The depletion session resulted in significant increases in depression scores compared with the sham control session. Six of 10 patients had a clinically significant relapse of their depression following the tryptophan depletion session. CONCLUSIONS: Rapid tryptophan depletion appears to reverse the antidepressant effect of bright light therapy in patients with SAD. This suggests that the therapeutic effects of bright light in SAD may involve a serotonergic mechanism.

Adult↗
PubMed1996

Seasonality of symptoms in anorexia and bulimia nervosa.

OBJECTIVE: Recent research has suggested that a large proportion of patients with bulimia nervosa have seasonal (winter) worsening of mood symptoms similar to seasonal affective disorder (SAD). The objectives of this study were to determine the specificity of this finding in anorexia and bulimia nervosa, and to further delineate the seasonal mood and eating patterns in bulimia nervosa. METHOD: A modified Seasonal Pattern Assessment Questionnaire (SPAQ) was administered to consecutive female patients assessed at an Eating Disorders Clinic with DSM-III-R diagnoses of bulimia nervosa (BN, N = 60) and anorexia nervosa (AN, N = 31), and to female nonclinical comparison subjects (NC, N = 50). RESULTS: The BN group had higher global seasonality scores and more presumptive diagnoses of SAD than the other two groups; the AN patients, whether they had the restricting or binge eating/purging subtype, did not differ from the NC subjects. Thirty-two percent of the identified seasonal BN patients did not have parallel worsening of mood and eating symptoms in the same season. DISCUSSION: These results suggest that seasonality of symptoms is specific to BN and that there may be separate mechanisms for the seasonality of mood and eating symptoms in some BN patients.

Adult↗
PubMed1996

Effect of stimulus intensity on prolactin and cortisol release induced by unilateral electroconvulsive therapy.

Prolactin (PRL) plasma levels rise several fold in response to electroconvulsive therapy (ECT). There is evidence that the magnitude of ECT-induced PRL release varies as a function of electrode placement with bilateral (BL) ECT, producing a larger PRL increase than does unilateral (UL) ECT. Although there is some evidence that the amount of PRL released by ECT may also vary as a function of stimulus intensity, the effect of stimulus intensity on the amount of PRL released by UL ECT has not been studied. This is an important question because it is with UL electrode placement that large differences in clinical efficacy as a function of stimulus intensity have been documented. We studied patients undergoing a course of UL ECT as the clinically indicated treatment for their illness. Subjects received low-dose (threshold) and high-dose (three times the threshold) ECT on two consecutive treatments. The order of low- and high-dose treatments was counterbalanced. Blood samples were drawn at 15-minute intervals before and for 1 hour after the administration of ECT and assayed for PRL and cortisol levels. Our results clearly indicate that the PRL and cortisol response to UL ECT-induced PRL release varies as a function of stimulus intensity. In fact, the amount of PRL released by high-dose UL ECT was nearly three times greater than that released by threshold stimulation. These results are consistent with the hypothesis advocating that the therapeutic advantage of high-intensity over low-intensity UL ECT is the result of greater seizure generalization and spread to subcortical regions and suggest that ECT-induced PRL release has the potential to distinguish a seizure induced by a therapeutic stimulus from a seizure induced by a stimulus known to have little therapeutic effect.

Adult↗
PubMed1996

Atypical depressive symptoms and clusters in unipolar and bipolar depression.

In order to examine differences in the atypical symptoms of depression between unipolar and bipolar patients, we studied 109 depressed patients (79 unipolar and 30 bipolar subjects) diagnosed with DSM-IV criteria. Patients were assessed using the Atypical Depression Diagnostic Scale (ADDS), a semi-structured interview that rates mood reactivity and other atypical depressive symptoms. Although atypical depression was common in this sample (28% of cases with definite atypical depression), no differences were found between the unipolar and bipolar patients in either the atypical symptom profile or the prevalence of an atypical depression diagnosis. The interrelationships between the atypical symptoms were also examined using a hierarchical cluster analysis. A five-cluster solution maximized differences between groups, with results suggesting that atypical depression may be a heterogeneous diagnosis.

Adult↗
PubMed1995

Prolactin response to buspirone challenge in the presence of dopaminergic blockade.

Buspirone-stimulated prolactin release has been employed as an indirect measure of central serotonin activity; however, it is not clear whether serotonergic or dopaminergic systems are responsible for this response. In an attempt to further elucidate the mechanism, we studied the prolactin response to buspirone in eight subjects in the presence of maximal dopaminergic receptor blockade with metoclopramide under placebo-controlled, double-blind conditions. The prolactin response to buspirone in the presence of metoclopramide was not statistically different from that to placebo under the same conditions. The demonstration of further prolactin release by a bolus of thyrotropin-releasing hormone under maximal dopaminergic receptor blockade provided evidence against potential pituitary prolactin depletion by metoclopramide. These results lend further support to a dopaminergic mechanism in buspirone-induced prolactin secretion; therefore, further caution is warranted in interpreting the results of this challenge test as a measure of serotonergic activity in the brain.

Adult↗
PubMed1995

Multicenter, placebo-controlled study of fluoxetine in seasonal affective disorder.

OBJECTIVE: The authors investigated the efficacy and safety of fluoxetine in the treatment of winter seasonal affective disorder. METHOD: Sixty-eight outpatients who met the DSM-III-R criteria for recurrent major depressive episodes, seasonal (winter) pattern, were randomly assigned to 5 weeks of treatment with fluoxetine, 20 mg/day (N = 36), or placebo (N = 32). The outcome measures included the 29-item modified Hamilton Depression Rating Scale, administered by experienced clinicians, and the self-rated Beck Depression Inventory; adverse events and safety data were also recorded. Clinical response was defined as a greater than 50% reduction in depression score between baseline and study termination. RESULTS: Both groups showed significant improvement. The fluoxetine group had lower depression scores at termination than the placebo group, but these differences did not achieve statistical significance. However, the rate of clinical response in the fluoxetine group (59%) was superior to that in the placebo group (34%). Post hoc analyses showed that the greatest fluoxetine responses were in the most markedly depressed patients and that overall response was greater for patients studied later in the season. Fluoxetine was well tolerated, and few subjects dropped out because of adverse events. CONCLUSIONS: On the basis of clinical response rate, fluoxetine appears to be an effective, well-tolerated treatment for seasonal affective disorder. Because the differences between fluoxetine and placebo in the continuous outcome measures did not reach statistical significance, further studies with larger study groups and longer treatment periods are required to conclusively demonstrate efficacy of fluoxetine for seasonal affective disorder.

Adult↗
PubMed1995

Treatment of seasonal affective disorder: a review.

OBJECTIVE: To review the status of current treatment of seasonal affective disorder (SAD). METHOD: Treatment studies of SAD published between January 1989 and March 1995 were identified using a computerized MEDLINE literature search. Additional citations were obtained from the reference sections of these articles. Studies included in this review were selected using operational methodologic criteria. RESULTS: Many studies support the efficacy of bright light therapy using a fluorescent light box. The best studied protocol is > 2500 lux white light for 2 hours per day, but newer protocols using 10,000 lux for 30 minutes have comparable response rates. Studies of light visors and other head-mounted devices also report similar response rates, but have not yet shown superiority over putative control conditions. There are fewer medication studies in SAD, but controlled studies suggest that fluoxetine, d-fenfluramine and propranolol are effective. Other treatments such as dawn simulation require further study. No studies of psychological treatments for SAD were found. Many studies had methodologic limitations, including brief treatment periods, small sample sizes, and lack of replication, that limit the generalizability of findings. CONCLUSION: There are several well-studied, effective treatments for SAD, including light therapy and medications. However, further research must be done to demonstrate sustained treatment response over time, to clarify the intensity-response relationship of light therapy, to clarify the role of light therapy and medications, and to assess combination treatments.

Humans↗