The impact of brain size on pilot performance varies with aviation training and years of education

Abstract

Previous studies have consistently reported age-related changes in cognitive abilities and brain structure. Previous studies also suggest compensatory roles for specialized training, skill, and years of education in the age-related decline of cognitive function. The Stanford/VA Aviation Study examines the influence of specialized training and skill level (expertise) on age-related changes in cognition and brain structure. This preliminary report examines the effect of aviation expertise, years of education, age, and brain size on flight simulator performance in pilots aged 45-68 years. Fifty-one pilots were studied with structural magnetic resonance imaging, flight simulator, and processing speed tasks. There were significant main effects of age (p < .01) and expertise (p < .01), but not of whole brain size (p > .1) or education (p > .1), on flight simulator performance. However, even though age and brain size were correlated (r = -0.41), age differences in flight simulator performance were not explained by brain size. Both aviation expertise and education were involved in an interaction with brain size in predicting flight simulator performance (p < .05). These results point to the importance of examining measures of expertise and their interactions to assess age-related cognitive changes.

Fig. 1

A theoretical construct depicting the influence of expert training and skill (aviation expertise) along with age and total intracranial volume (TIV) -adjusted whole brain volume on flight simulator performance in pilots.

Fig. 2

Scatter plots of (a) flight summary score with age, (b) whole brain volume with age, and (c) flight summary score with whole brain volume. Whole brain volume is total intracranial volume (TIV) -adjusted. All points on the graph are divided into the three aviation expertise levels (see legend). Correlations are provided on each graph. ¹Note, the distribution of whole brain size is concentrated toward larger brain volume; however, there is no correlation between brain size and expertise. VFR = rated for flying under visual flight rules only; IFR = rated for flying under instrument flight rules; CFII = certified flight instructor; ATP = rated for flying air-transport planes.

Fig. 3

Relationship between flight simulator performance and whole brain volume: Scatter plot according to aviation expertise rating. Trend lines are shown for each aviation rating group as per the parameters estimated by the general linear model: Predicted flight simulator summary Z-score = 2.022 + 0.001*(whole brain volume) + 0.260*(rating) + 0.004*(whole brain volume)*(rating) −0.034*(average age for each rating group) where Rating of −1, 0, and 1 represents VFR, IFR, and CFII/ATP, respectively. Whole brain volume is residualized on TIV. VFR = rated for flying under visual flight rules only; IFR = rated for flying under instrument flight rules; CFII = certified flight instructor; ATP = rated for flying air-transport planes.