Animal and clinical studies of vasopressin effects on learning and memory

Cognitive deficits of attention deficit disorder in childhood are poorly responsive to presently available medication. Vasopressin derivatives have been reported to enhance learning and memory in animals and in normal humans in controlled studies. This study reports on the effects of vasopressin on learning in rats and in children with learning disorders. Vasopressin treatment three times weekly for 6 weeks in rats appeared to be more effective in enhancing learning and retarding extinction than did vasopressin treatment given only at the beginning of learning and again at the start of extinction. These effects were also shown to be affected by pharmacogenetic factors, since in six inbred mouse strains some showed retarded extinction with vasopressin and others did not. In 17 children with attention and learning disorders, vasopressin derivative was given daily for 10 days and compared with 10 days of placebo treatment in a randomized, crossover, double-blind design. Story memory plus position learning were significantly improved by vasopressin derivative compared with placebo. The same trend of improvement was observed in nine Down's syndrome patients. In 15 other children with attention and learning disorders, a single dose of vasopressin derivative was compared with placebo in a randomized, crossover, double-blind design, and no benefit was found. These parallel animal and human studies suggest that repeated, but not single-dose, vasopressin treatment may benefit childhood learning disorders.