The whole-brain N-acetylaspartate correlates with education in normal adults

N-acetylaspartate (NAA) is an index of neuronal integrity. We hypothesized that in healthy subjects its whole brain concentration (WBNAA) may be related to formal educational attainment, a common proxy for cognitive reserve. To test this hypothesis, 97 middle aged to elderly subjects (51–89 years old, 38% women) underwent brain magnetic resonance imaging and non-localizing proton spectroscopy. Their WBNAA was obtained by dividing their whole-head NAA amount by the brain volume. Intracranial volume and fractional brain volume, a metric of brain atrophy, were also determined. Each subject's educational attainment was the sum of his/her years of formal education. In the entire group higher education was associated with larger intracranial volume. The relationship between WBNAA and education was observed only in younger (51–70 years old) participants. In this group, education explained 21% of the variance in WBNAA. More WBNAA was related to more years of formal education in adults and younger elders. Prospective studies can determine whether this relationship reflects a true advantage from years of training versus innate characteristics predisposing a subject to higher achievements later in life. We propose that late-life WBNAA may be more affected by other factors acting at midlife and later.