Secretory pattern of vasopressin in plasma and cerebrospinal fluid of patients with dementia and of two control groups

Skelleftea Hospital, Sweden.

Since the description of its antidiuretic effect in 1913, a variety of functions have been attributed to vasopressin, one of the most controversial throughout the years probably being its effect on memory processes. In an attempt to study the actual secretory rhythm of vasopressin in humans with demonstrated impaired memory, the plasma and cerebrospinal fluid levels of the peptide have been examined during 24 h in a group of patients with dementia, and their values compared with two healthy control groups of young and elderly volunteers. Patients with dementia had higher circulating levels of vasopressin in plasma than the healthy participants and the differences were statistically significant when compared with the healthy elderly (p = 0.003). This difference is not age-related because both groups were in the same age range. A possible explanation could be the higher plasma osmolality measured in the patients with dementia, despite the fact that their levels were within the normal ranges. The different results could not be attributed to changes in electrolytes or blood pressure because these parameters were similar in all groups (p = NS). But more interesting, perhaps, is the secretory pattern found in all three groups. The pattern is biphasic, with two significant peaks: at 16.00 h (p = 0.032) and at night (p = 0.002). This pattern was similar in all cases and in all groups. The total nocturnal secretion of vasopressin is higher than the diurnal secretion (p = 0.02) only in the plasma because the cerebrospinal fluid values were higher during the day.(ABSTRACT TRUNCATED AT 250 WORDS)

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