Biology of depression

Acute modafinil exposure reduces daytime sleepiness in abstinent methamphetamine-dependent volunteers

The purpose of this study was to evaluate the effects of acute, oral modafinil (200 mg) exposure on daytime sleepiness in methamphetamine (Meth)-dependent individuals. Eighteen Meth-dependent subjects were enrolled in a 7-d inpatient study and were administered placebo or modafinil on day 6 and the counter-condition on day 7 (randomized) of the protocol. Subjects completed several subjective daily assessments (such as the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, Beck Depression Inventory and visual analogue scale) throughout the protocol as well as objective assessments on days 5-7, when the Multiple Sleep Latency Test was performed. The results of the current study suggest that short-term abstinence from Meth is associated with increased daytime sleepiness and that a single dose of 200 mg modafinil reduces daytime somnolence in this population. In addition, a positive correlation was found between subjective reporting of the likelihood of taking a nap and craving and desire for Meth, as well as the likelihood of using Meth and whether Meth would make the participant feel better. The results of this study should be considered when investigating candidate medications for Meth-dependence, especially in those individuals who attribute their Meth use to overcoming deficits resulting from sleep abnormalities.

Reproductive and metabolic abnormalities associated with bipolar disorder and its treatment

Women with mood disorders, especially bipolar disorder (BD), have been shown to have high rates of reproductive and metabolic dysfunction. The available data on the functional, anatomic, and clinical neuroendocrine abnormalities in women with BD suggest a two-tiered relationship with mood pathology. First, many of the medications commonly used in the treatment of BD can have deleterious effects on blood levels of reproductive hormones and consequently on the hypothalamic-pituitary-gonadal (HPG) axis and reproductive function. Studies that have specifically addressed the association between psychotropic medications and menstrual abnormalities, polycystic ovary syndrome, and overall reproductive endocrine function in women with BD have found high rates of HPG irregularities in women with BD. Second, there is evidence of reproductive dysfunction in women with BD prior to treatment. In addition, many of the psychotropic medications used in the treatment of BD are associated with weight gain, insulin resistance, and dyslipidemia. These metabolic side effects further compound the neuroendocrine system dysregulation in women with BD. Current understanding of the reproductive and metabolic function in women with BD points to vulnerability, which in turn increases the risk of later-life cardiovascular disease and diabetes, among other morbidities, for women with BD.

Alpha lipoic acid: a novel treatment for depression

Insulin resistance has been associated with people diagnosed with depression. Conversely, it has also been documented that diabetics have an increased risk of depression. Evidence suggests that insulin activity plays a role in serotonergic activity by increasing the influx of tryptophan into the brain. This increased influx of tryptophan has been shown to result in an increase in serotonin synthesis. In accordance with the serotonin theory of depression, it may be possible to treat depression by increasing insulin activity. The antioxidant alpha lipoic acid has been shown to increase insulin sensitivity and is used to treat people with diabetes. Therefore, the nutrient alpha lipoic acid should be clinically tested as an adjunct treatment for depression.

Rapid and sensitive determination of catecholamines and the metabolite 3-methoxy-4-hydroxyphen-ethyleneglycol using HPLC following novel extraction procedures

In the present study assays were improved for the determination of free catecholamines and 3-methoxy-4-hydroxyphenethyleneglycol (MHPG), the major metabolite of peripheral and central noradrenaline. The compounds were extracted by a fluid phase extraction: a diphenyl boric acid method for the purification of catecholamines and an ethyl acetate extraction for MHPG were used, respectively. High-performance liquid chromatography with electrochemical detection was employed for quantitative analysis. In previous studies, significant differences between plasma concentrations of these substances in normal volunteers and hospital patients were demonstrated. Therefore, we established valid reference values for a hospital population. Blood and urine samples of 59 patients without disorders and medication affecting catecholamine synthesis and metabolism or the activity of the sympatho-adrenal system were collected and analyzed for free and total (free plus conjugated) MHPG, noradrenaline (NA), adrenaline (A) and dopamine (DA); total MHPG was assayed after enzymatic hydrolysis of conjugates. Our data clearly demonstrate that these methods are sensitive, specific, rapid, and can easily be standardized. The intra- and inter-assay precision were high (CV 2.6-5.3% and 4.3-6.9% for plasma, CV 3.8-4.9% and 5.1-8.2% for urine, respectively). For plasma, the mean concentrations +/- SD were determined to be 20.82+/-4.70 pmol/ml for free MHPG, 68.43+/-16.21 pmol/ml for total MHPG, 2.11+/-0.24 pmol/ml for NA and 0.31+/-0.08 pmol/ml for A. For 24h-urine the mean concentrations +/-SD were determined to be 0.44+/-0.13 mmol/24h for free MHPG, 8.79+/-2.13 mmol/24h for total MHPG, 169.8+/-58.25 nmol/24h for NA, 62.19+/-21.79 nmol/24h for A and 757.2+/-382.6 nmol/24h for DA. In summary, these novel and rapid methods can clearly be employed in a routine clinical setting.

Enhancing central and peripheral insulin activity as a strategy for the treatment of endogenous depression--an adjuvant role for chromium picolinate?

Depression is often associated with insulin resistance, owing to cortisol overproduction; conversely, many studies suggest that diabetics are at increased risk for depression. Recent evidence indicates that insulin is transported through the blood-brain barrier and influences brain function via widely distributed insulin receptors on neurons. These receptors are particularly dense on catecholaminergic synaptic terminals, and, while effects are variable dependent on brain region, several studies indicate that insulin promotes central catecholaminergic activity, perhaps by inhibiting synaptic re-uptake of norepinephrine. Additionally, it is well known that insulin enhances serotonergic activity in increasing blood-brain barrier transport of tryptophan. Since impaired monoaminergic activity in key brain pathways is believed to play an etiological role in depression, techniques which promote effective insulin activity, both centrally and peripherally, may be therapeutically beneficial in this disorder. This may rationalize anecdotal reports of improved mood in clinical depressives and diabetics receiving the insulin-sensitizing nutrient chromium picolinate. This nutrient, perhaps in conjunction with other insulin-sensitizing measures such as low-fat diet and aerobic exercise training (already shown to be beneficial in depression), should be tested as an adjuvant for the treatment and secondary prevention of depression.

Different linkage of depression to hypercortisolism early versus late after stroke. A 3-year longitudinal study

BACKGROUND AND PURPOSE

Using the dexamethasone suppression test, we studied the suppressibility of the cortisol axis and its clinical determinants at various time points after stroke. A major aim was to examine the dexamethasone test as a diagnostic tool for the diagnosis of major depression in stroke patients.

METHODS

The dexamethasone suppression test, major depression, functional ability, and disorientation were assessed in a cohort of 70 patients with acute stroke and after 3 months (n = 63) and 3 years (n = 43).

RESULTS

Early after stroke, 24% of the patients were nonsuppressors, with about the same proportion at 3 months (22%) and 3 years (21%). None of the controls (17 healthy elderly volunteers) were nonsuppressors. High cortisol levels early after stroke were significantly associated with functional impairment (r = 0.35; p = 0.003) and disorientation (r = 0.27; p = 0.03). Three years after stroke, high postdexamethasone cortisol levels were significantly associated with major depression (r = 0.57; p < 0.001). The sensitivity of the dexamethasone test was 70% and the specificity 97%. In a longitudinal analysis of the long-term survivors (n = 42), postdexamethasone cortisol values at 3 months predicted major depression at 3 years.

CONCLUSIONS

Hypercortisolism is associated with major depression late (3 years) but not early (0-3 months) after stroke. Patients with hypercortisolism 3 months after stroke are at risk of major depression later in the course and warrant careful follow-up from a psychiatric viewpoint.

Biochemical correlate of depression in children

The degree of depression in 88 abandoned children was analysed through a depression rating scale adapted to prepubertal children. The items were grouped into three dimensions: sociological-relational, psychological and biological. In 46 children from this sample it was dosed plasmatic cortisol and the urinary excretion of catecholamine, VMA, HVA and 5-HIAA. When analysing the principal components, the sociological and psychological dimensions were the most important ones in the sample, followed by age and catecholamine variables. The group of male depressed children presented a higher level of catecholamine urinary excretion and a lower peak of plasmatic cortisol than the non-depressed group. The variable age, in both sexes, was correlated with the biochemical variable catecholamine. Biochemical alterations are present in depressed children but it is difficult to show a correlation of dependence between them and the phenomenological aspects of depression.

Stressor-induced anhedonia in the mesocorticolimbic system

It has been suggested that uncontrollable stressors induce motivational changes in animals which are reminiscent of reward alteration in human depression. Although there is considerable support for this position, most animal models of depression do not adequately address this issue. The present review suggests that stressor-induced reductions in the rewarding value of electrical brain stimulation (ICSS) from the mesocorticolimbic system may simulate the anhedonia of human depression. The magnitude, severity and the site of these stressor-induced reward alterations within the mesocorticolimbic system vary with the strain of animal employed. The anhedonic effects of stressors are attenuated by treatments which influence mesocorticolimbic DA turnover, including systemic antidepressant and intraventricular neuropeptide administration. Although the diverse symptom profile of depression should be addressed by consideration of the constellation of behavioral disturbances induced by stressors, considerable emphasis should be devoted to an assessment of reward loss in depression. The implications of these data to the stressor depression topography and the potential role of mesocorticolimbic DA in depression and anhedonia are discussed.

CSF monoamine metabolites and somatostatin in Alzheimer's disease and major depression

Decreased cerebrospinal fluid (CSF), somatostatinlike immunoreactivity (SLI) and alterations in the CSF monamine metabolites 3-methoxy-4-hydroxyphenylethylglycol (MHPG), 5-hydroxyindoleacetic acid (5-HIAA), and homovanillic acid (HVA) have been reported in patients with probable Alzheimer's disease (AD) and in patients with major depression. In this study, we found CSF SLI to be significantly lower in a large group of AD patients (n = 60) and in a group of age-matched patients with major depression (n = 18) as compared with normal controls (n = 12). Mean CSF, MHPG, 5-HIAA, and HVA levels were not significantly different among diagnostic groups. Within a group of "depressed" AD patients, CSF levels of 5-HIAA showed a significant positive correlation (p = 0.03) with CSF SLI; a similar relationship was found within the group of patients with major depression. Further exploration of the relationship between the somatostatin and serotonin systems may provide clues as to how neuropeptides interact with monoamine neurotransmitters and what role they have in depression.

Some basic aspects of reversible inhibitors of monoamine oxidase-A

A novel class of antidepressants is emerging with considerable therapeutic potential: reversible inhibitors of monoamine oxidase type A (RIMA). Moclobemide (Aurorix) is a representative RIMA. It is a fully and rapidly reversible inhibitor of MAO-A with a correspondingly intermediate duration of action in vivo. It is free of hepatotoxicity and produces a much weaker potentiation of the tyramine pressor effect than the classical irreversible MAO inhibitors. Interaction of MAO inhibitors and monoamine reuptake inhibitors with tyramine is discussed on the basis of experiments in conscious rats. The issue of tyramine content of foods and beverages has been reinvestigated and its relevance for treatment with RIMA antidepressants is discussed. Recently observed antihypoxic (neuroprotective) effects of moclobemide suggest new indications for this compound.