Intranasal insulin improves memory in humans: superiority of insulin aspart.
There is compelling evidence that intranasal administration of regular human insulin (RH-I) improves memory in humans. Owing to the reduced tendency of its molecules to form hexamers, the rapid-acting insulin analog insulin aspart (ASP-I) is more rapidly absorbed than RH-I after subcutaneous administration. Since after intranasal insulin administration, ASP-I may also be expected to access the brain, we examined whether intranasal ASP-I has stronger beneficial effects on declarative memory than RH-I in humans. Acute (40 IU) and long-term (4 x 40 IU/day over 8 weeks) effects of intranasally administered ASP-I, RH-I, and placebo on declarative memory (word lists) were assessed in 36 healthy men in a between-subject design. Plasma insulin and glucose levels were not affected. After 8 weeks of treatment, however, word list recall was improved compared to placebo in both the ASP-I (p<0.01) and the RH-I groups (p<0.05). ASP-I-treated subjects performed even better than those of the RH-I-treated group (p<0.05). Our results indicate that insulin-induced memory improvement can be enhanced by using ASP-I. This finding may be especially relevant for a potential clinical administration of intranasal insulin in the treatment of memory disorders like Alzheimer's disease.
Benedict
Christian
C
Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany. benedict@kfg.uni-luebeck.de
Hallschmid
Manfred
M
Schmitz
Katrin
K
Schultes
Bernd
B
Ratter
Frank
F
Fehm
Horst L
HL
Born
Jan
J
Kern
Werner
W
D000281:Administration, Intranasal; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001786:Blood Glucose / Q000187:drug effects; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007328:Insulin / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000097:blood; D061267:Insulin Aspart; D008297:Male; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D009483:Neuropsychological Tests
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D061267:Insulin Aspart