Impaired melatonin secretion in patients with Wernicke-Korsakoff syndrome

Melatonin (MT) undergoes circadian changes in response to external light conditions and has been implicated in the control of other circadian hormone variations. Alcohol inhibits MT secretion in healthy subjects. The purpose of the present investigation was to elucidate whether patients with Wernicke-Korsakoff syndrome (WKS) also have impaired MT secretion after a period of prolonged alcohol abstention. If so, it would be of interest to find out whether this affects cortisol rhythmicity.

Seven patients with WKS and 8 healthy controls were included in the study. Venous blood was sampled every 2nd h between 18.00 and 08.00 hours, and urine collected between 22.00 and 07.00 hours.

Department of Internal Medicine, Endocrinology Section, Södersjukhuset, Stockholm.

Peak serum MT values during the night, total nocturnal MT secretion (estimated by MT incremental areas), and urinary excretion of MT were determined in each participant. Serum cortisol levels were determined in the patients at 18.00, 02.00 and 08.00 hours.

Patients with WKS had a markedly reduced nocturnal secretion of MT compared to healthy volunteers (MT incremental areas 0.33 +/- 0.21 vs. 1.60 +/- 0.29 nmol L-1 h-1, mean +/- SEM; P < 0.005). Amongst the patients, the serum cortisol level was higher in the morning than in the afternoon (331 +/- 46 vs. 240 +/- 52 nmol L-1; P < 0.01), and showed a nadir during the night (138 +/- 45 nmol L-1) as in normal individuals.

Patients with WKS have markedly reduced nocturnal secretion of MT. The exact mechanism behind this finding has to be further elucidated. However, it is of interest to note that despite the lack of clearcut circadian MT changes. WKS patients retain normal cortisol secretion, thus suggesting that MT rhythm may not be obligatory for the proper control of circadian cortisol rhythmicity.