Higher serum insulin-like growth factor-1 is associated with better cognitive performance in persons with mild cognitive impairment.
BACKGROUND
Serum insulin-like growth factor-1 (IGF-1) is a mitogenic peptide involved in the regulation of cell proliferation, differentiation, and apoptosis in a wide variety of cells and tissues. Recent research suggests higher circulating levels of IGF-1 are associated with better cognitive performance in healthy older adults and in early stages of Alzheimer's disease, although the cognitive profile associated with elevated IGF-1 has not been examined in persons with mild cognitive impairment.


METHODS
Thirty-one participants (age: 83.71 ± 3.59 years; 58% women) with mild cognitive impairment completed neuropsychological testing and 12-hour fasting blood draw to assess serum IGF-1.


RESULTS
Partial correlations between serum IGF-1 and neuropsychological measures were conducted, adjusting for insulin, body mass index, and age. Higher IGF-1-values were associated with better global cognition (Modified Mini Mental State Exam: r = 0.39, P = 0.04) and verbal list learning (Hopkins Verbal Learning Test learning: r = 0.38, P = 0.05), Hopkins Verbal Learning Test free recall (r = 0.41, P = 0.03), and Hopkins Verbal Learning Test recognition discriminability (r = 0.46, P = 0.01). A similar trend emerged for executive function as tested by the Frontal Assessment Battery (r = 0.33, P = 0.09).


CONCLUSIONS
Results suggest higher levels of serum IGF-1 are associated with better cognitive performance in persons with mild cognitive impairment, particularly on tests of learning and memory. These findings suggest IGF-1 may be neuroprotective not only in healthy older adults, but also in adults in the earliest stages of Alzheimer's disease. Further investigation is needed to clarify the nature of this relationship, particularly prospective studies.
Department of Psychology, Kent State University, Kent, OH, USA.
Dayana
D
Calvo
John
J
Gunstad
Lindsay A
LA
Miller
Ellen
E
Glickman
Mary Beth
MB
Spitznagel
D000369:Aged, 80 and over; D060825:Cognitive Dysfunction / Q000097:blood*; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data
D007334:Insulin-Like Growth Factor I
cognitive functioning; insulin-like growth factor; mild cognitive impairment