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Biomedical subjects

A J Cleare

Publications and source records attributed to A J Cleare.

43 records · Page 3Linked to original sources
PubMed1995

Contrasting neuroendocrine responses in depression and chronic fatigue syndrome.

Hypothalamic-pituitary-adrenal (HPA) axis and central 5-HT function were compared in chronic fatigue syndrome (CFS), depression and healthy states. 10 patients with CFS and 15 patients with major depression were matched for age, weight, sex and menstrual cycle with 25 healthy controls. Baseline-circulating cortisol levels were highest in the depressed, lowest in the CFS and intermediate between the two in the control group (P = 0.01). Prolactin responses to the selective 5-HT-releasing agent d-fenfluramine were lowest in the depressed, highest in the CFS and intermediate between both in the healthy group (P = 0.01). Matched pair analysis confirmed higher prolactin responses in CFS patients than controls (P = 0.05) and lower responses in depressed patients than controls (P = 0.003). There were strong inverse correlations between prolactin and cortisol responses and baseline cortisol values. These data confirm that depression is associated with hypercotisolaemia and reduced central 5-HT neurotransmission and suggest that CFS may be associated with hypocortisolaemia and increased 5-HT function. The opposing responses in CFS and depression may be related to reversed patterns of behavioural dysfunction seen in these conditions. These findings attest to biological distinctions between these disorders.

Adult↗
PubMed1995

The effect of tryptophan depletion and enhancement on subjective and behavioural aggression in normal male subjects.

In order to investigate the link between aggression and 5-HT, we looked at effects of changes in plasma tryptophan on healthy male subjects. Twenty-four with high trait aggression (H) and 24 with low (L) drank an amino acid mixture with (T+) or without (T-) tryptophan. These caused plasma tryptophan enhancement and depletion, respectively, at 4.5 h. Group H subjects given T- became more angry, aggressive, annoyed, hostile and quarrelsome on subjective measures, whereas those given T+ responded in the opposite way. On a behavioural measure of aggression, group H subjects responded more aggressively after T- than T+. In contrast, there was no consistent effect on subjective or behavioural aggression in group L subjects. Feelings of well-being in group H were decreased by T- and increased by T+. In group L, T+ reduced feelings of well-being, possibly due to the sedative effect of tryptophan in this group, which correlated positively with plasma tryptophan concentration. Changes in plasma tryptophan are probably followed by changes in central 5-HT turnover. We conclude that, in those with pre-existing aggressive traits, acute falls in central 5-HT can cause increased subjective and objective aggression, while rises can have the opposite effect. The absence of changes in a low aggressive group suggests that the primary effect may be on impulsivity, possibly mediated by 5-HT1a receptors, expressing underlying aggressive traits. The findings on mood changes provide support for earlier reports of a lowering of mood with tryptophan depletion.

Adult↗
PubMed1995

Neuroendocrine evidence for an association between hypothyroidism, reduced central 5-HT activity and depression.

OBJECTIVE: The incidence of depression in those with hypothyroidism is increased compared to healthy populations, though the mechanism for this is unclear. We tested the hypothesis that central 5-HT activity is reduced in hypothyroidism, and that this subsequently lowers the threshold for developing depression. PATIENTS: Twenty subjects entered the study: 10 drug free hypothyroid patients and 10 age, sex, weight and menstrual cycle matched controls. MEASUREMENTS: Patients were diagnosed as being depressed using DSM-IIIR criteria and rated using the Hamilton Rating Scale for Depression (HAM-D) and Beck Depression Inventory (BDI). Cortisol and prolactin responses to dexfenfluramine, a centrally acting 5-HT releasing agent, were used as an index of central 5-HT responsivity. RESULTS: Both cortisol and PRL responses were reduced in the hypothyroid group relative to the controls. Peak cortisol responses were inversely correlated to TSH levels. Four of the 10 patients were clinically depressed. Depressed patients had higher TSH levels than their non-depressed counterparts, and TSH levels were positively correlated with HAM-D and BDI scores. CONCLUSIONS: These findings support animal work suggesting that hypothyroidism reduces central 5-HT activity. They also suggest a threshold effect in that higher TSH levels predicted both lower 5-HT mediated endocrine responses and the presence of clinical depression.

Adult↗