Relationship between Insulin-Resistance Processing Speed and Specific Executive Function Profiles in Neurologically Intact Older Adults.
This study investigated the relationship between insulin-resistance and constituent components of executive function in a sample of neurologically intact older adult subjects using the homeostasis model assessment (HOMA-IR) and latent factors of working memory, cognitive control and processing speed derived from confirmatory factor analysis. Low-density lipoprotein (LDL), mean arterial pressure (MAP), along with body mass index (BMI) and white matter hypointensity (WMH) were used to control for vascular risk factors, adiposity and cerebrovascular injury. The study included 119 elderly subjects recruited from the University of California, San Francisco Memory and Aging Center. Subjects underwent neuropsychological assessment, fasting blood draw and brain magnetic resonance imaging (MRI). Partial correlations and linear regression models were used to examine the HOMA-IR-executive function relationship. Pearson correlation adjusting for age showed a significant relationship between HOMA-IR and working memory (rp = -.18; p = .047), a trend with cognitive control (rp = -.17; p = .068), and no relationship with processing speed (rp = .013; p = .892). Linear regression models adjusting for demographic factors (age, education, and gender), LDL, MAP, BMI, and WMH indicated that HOMA-IR was negatively associated with cognitive control (r = -.256; p = .026) and working memory (r = -.234; p = .054). These results suggest a greater level of peripheral insulin-resistance is associated with decreased cognitive control and working memory. After controlling for demographic factors, vascular risk, adiposity and cerebrovascular injury, HOMA-IR remained significantly associated with cognitive control, with working memory showing a trend. These findings substantiate the insulin-resistance-executive function hypothesis and suggest a complex interaction, demonstrated by the differential impact of insulin-resistance on processing speed and specific aspects of executive function.
1Memory and Aging Center,University of California,San Francisco,San Francisco,California.
Darvis T
DT
Frazier
1Memory and Aging Center,University of California,San Francisco,San Francisco,California.
Brianne M
BM
Bettcher
1Memory and Aging Center,University of California,San Francisco,San Francisco,California.
Shubir
S
Dutt
1Memory and Aging Center,University of California,San Francisco,San Francisco,California.
Nihar
N
Patel
3Department of Neurology,School of Medicine,University of California,Davis,Davis,California.
Dan
D
Mungas
4Department of Pathology and Laboratory Medicine,University of California,Davis,Davis,California.
Joshua
J
Miller
4Department of Pathology and Laboratory Medicine,University of California,Davis,Davis,California.
Ralph
R
Green
1Memory and Aging Center,University of California,San Francisco,San Francisco,California.
Joel H
JH
Kramer
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001786:Blood Glucose; D001794:Blood Pressure / Q000502:physiology; D001921:Brain / Q000502:physiology*; D056344:Executive Function / Q000502:physiology*; D005215:Fasting / Q000097:blood; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D007600:Judgment; D008077:Lipoproteins, LDL / Q000097:blood; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology
D001786:Blood Glucose; D008077:Lipoproteins, LDL
Cognitive control; Confirmatory factor analysis; Executive function; Homeostatic model assessment; Insulin-resistance; Processing speed; White matter hypointensity; Working memory