Insulin Tolerance Test: human growth hormone response and insulin resistance in primary unipolar depressed, bipolar depressed and control subjects

Abstract

SynopsisPreliminary data from the National Institute of Mental Health – Clinical Research Branch Collaborative Program on the Psychobiology of Depression dealing with the human growth hormone (hGH) response to the Insulin Tolerance Test (ITT) during the pre-treatment (drug-free) period of the study are presented in this paper. Data are reported for 54 unipolar depressed, 21 bipolar depressed, and 40 normal control subjects, who represent approximately 50% of the final subject sample to be studied. In this population the unipolar depressed subjects showed a significantly greater resistance to insulin-induced hypoglycaemia than bipolar and control subjects. After applying the inclusion/exclusion criteria necessary to interpret hGH responses accurately, the data from only 54 subjects were acceptable. Mean peak hGH concentrations were not significantly different among the three groups. There was, however, a significant difference in the distributions of the hGH peak response, with the bipolar depressed population demonstrating greater variability in response than unipolar and control populations. These findings are discussed as they relate to previous reports and theoretical considerations.

Psychological symptoms and insulin sensitivity in adolescents

“…Our findings parallel a series of studies in the adult literature that have found links between depressive disorders or severity of depressive symptoms and decreased insulin sensitivity in women and men (3, 6–8, 11). Despite meal‐level sex differences in depressive symptoms and insulin resistance, the observed relationship between depression and insulin was not significantly different among adolescent boys and girls.…”

“…Overweight youth have decreased insulin sensitivity compared to their non‐overweight counterparts, placing them at heightened risk for negative health consequences including type 2 diabetes (2). However, evidence from adult studies suggests that psychological factors may also affect insulin sensitivity (3–11). In overweight and non‐overweight adults, sub‐clinical and clinical threshold depressive symptoms are correlates of, and potential risk factors for, the development of decreased insulin sensitivity (3, 6–10), type 2 diabetes (5, 12, 13), and other aspects of the metabolic syndrome (4, 11).…”

“…However, evidence from adult studies suggests that psychological factors may also affect insulin sensitivity (3–11). In overweight and non‐overweight adults, sub‐clinical and clinical threshold depressive symptoms are correlates of, and potential risk factors for, the development of decreased insulin sensitivity (3, 6–10), type 2 diabetes (5, 12, 13), and other aspects of the metabolic syndrome (4, 11). The degree of psychosocial stress and anxiety symptoms in a large community sample of women also has been shown to be significantly related to measures of insulin sensitivity, even after accounting for body mass index (4).…”

Investigations with the Specific μ-Opiate Receptor Agonist Fentanyl in Depressive Patients: Growth Hormone, Prolactin, Cortisol, Noradrenaline and Euphoric Responses

“…Data from subjects in whom base line GH plasma concentrations exceeded 5 ng/ml were excluded from evaluation according to Catt [1970] and Koslow et al [1982], Maximum PRL responses and maximum GH responses were compared using Student's t test for unpaired data or Mann-Whitney U test, if appropriate. NA, cortisol and VAS responses of patients and controls were compared at indicated time points by Student's t test for unpaired data or Mann-Whitney U test, respectively.…”

Biological Alterations in Depression

“…The correlation between depressive symptoms and metabolic syndrome is slightly higher in monozygotic twins than dizygotic twins, suggesting that genetics play a critical role in both disorders (McCaffery et al, 2003). Resistance to insulin, which is a risk factor for developing metabolic syndrome, is a common occurrence in depressed patients (Koslow et al, 1982;Okamura et al, 2000;Winokur et al, 1988), which suggests that insulin links depression with metabolic syndrome. Insulin exerts dosedependent effects on food intake and energy regulation.…”