Serum insulin like growth factor-1 is associated with working memory, executive function and selective attention in a sample of healthy, fit older adults

The present study examined the association between serum insulin like growth factor-1 (IGF-1) concentrations and cognitive function in a sample of healthy, fit older adults (age: 70.8±9.3 years, body mass index (BMI): 27.3±5.7). Participants reported to the laboratory and basic anthropometric data were collected, followed by a fasted blood draw to quantify serum IGF-1. Participants then underwent cognitive testing that included the Mini-Mental Status Exam (MMSE), Trail Making Test A and B, Ruff's 2 and 7 test of selective attention and Letter Number Sequencing. Results showed the participants were generally cognitively intact (MMSE 27.6±1.8). Significant partial correlations (controlled for age, gender and years of education) emerged between serum IGF-1 concentrations and the total (r=0.381, P=0.030) and longest trial (r=0.455, P=0.011) on Letter Number Sequencing. Similar partial correlations yielded significant relationships between serum IGF-1 and Ruff's Automatic Detection Errors (r=−0.495, P=0.006), Controlled Speed Errors (r=−0.598, P=0.002) and errors made on the Trial Making Test part B (r=−0.466, P=0.010). These findings suggest that fasting levels of serum IGF-1 are related to higher levels of cognitive performance in healthy older adults, including working memory, selective attention and executive function. Further work is needed to more clearly determine possible mechanisms.

Research highlights▶Significant relationship between serum IGF-1 and working memory described in a population of healthy older adults. ▶Significant relationship described for errors made on test of selective attention and serum IGF-1. ▶Significant relationship descried for errors made on a test of executive function and serum IGF-1.