a. Demographic data
At TP1, a total of 60 participants were enrolled with 20 participants for each of the three groups, i.e., C+, C- and HC groups. At TP2, due to attrition from loss to follow-up, new cancer, new memory problems, refusal and death, the cohort consisted of 10 participants for the C+ group, 12 participants for the C- group, and 13 participants for HC group [9]. There were no significant differences among the groups in age (p = 0.75), education (p = 0.80) or race (p = 0.37) (Table 1). More detailed clinical and demographic information for this cohort has been reported [9]. In the C+ group, 80% of survivors had Stage II breast cancer. The C- group consisted of 50% survivors in stage 0, 33% survivors in stage I and 17 % survivors in stage II. In the C+ group, 90% of survivors had treatment with non-trastuzumab regimen and 10% of survivors with trastuzumab regimen (Table 1).
b. Gyrification results
There were no significant gyrification differences at TP1 between C+ versus C-, C+ versus HC, and C- versus HC (p > 0.05, Bonferroni corrected).
Within the C+ group, gyrification was significantly increased in 6 regions and decreased in 2 regions longitudinally over the 2-year study interval (p < 0.05, Bonferroni corrected) (Table 2). The brain regions with increased surface gyrification in the C+ group included the following (Bonferroni corrected): left pars opercularis gyrus (p < 0.001), right superior temporal gyrus (p < 0.001), right middle temporal gyrus (p < 0.001), right precuneus gyrus (p < 0.001), right paracentral gyrus (p < 0.001) and right fusiform gyrus (p = 0.004) (Fig. 1). The brain regions with decreased surface gyrification in the C+ group included the following (Bonferroni corrected): left superior parietal gyrus (p = 0.030) and left cuneus gyrus (p = 0.030).
Within the C- group, brain surface gyrification was significantly decreased in 7 regions (p < 0.05, Bonferroni corrected) and no regions showed increased gyrification. Decreased surface gyrification within the C- group was noted in left fusiform gyrus (p < 0.001), left lingual gyrus (p < 0.001), left isthmus cingulate gyrus (p < 0.001), left supramarginal gyrus (p = 0.001), right lateral orbitofrontal gyrus (p = 0.006), right inferior temporal gyrus (p = 0.001) and right caudal middle frontal gyrus (p < 0.001) (Fig. 2).
In the HC group, brain surface gyrification was significantly decreased in 9 regions (p < 0.05, Bonferroni corrected) and no regions showed increased gyrification longitudinally. Decreased brain surface gyrification was noted in the following regions: left superior frontal gyrus (p < 0.001), left postcentral gyrus (p < 0.001), left precuneus gyrus (p < 0.001), left paracentral gyrus (p < 0.001), left caudal anterior cingulate gyrus (p < 0.001), left transverse temporal gyrus (p < 0.001), right superior frontal gyrus (p < 0.001), right caudal middle frontal gyrus (p < 0.001) and right supramarginal gyrus (p < 0.001) (Fig. 3).
There was no significant gyrification difference noted in group-by-time interaction analysis (p > 0.05, Bonferroni corrected).
c. NP testing scores
The detailed results of the NIH Toolbox cognition battery testing scores have been reported in our prior study of cortical thickness in the same cohort [9]. Briefly, the C+ group showed significantly decreased total composite score (p = 0.01), fluid composite score (p = 0.03) and picture vocabulary score (p = 0.04) across the 2-year interval. No significant changes in NP scores were noted in C- and HC group at a threshold of p values at 0.05.
d. Correlation between gyrification and NP scores
The correlation analysis was performed between the significant gyrification alterations within each group over time and the 3 NP composite scores. A significant negative correlation was noted between longitudinal changes in the crystallized composite scores and right paracentral gyrification values in the C+ group (p = 0.01, R = -0.76). No significant correlations were noted in the C- or the HC group (Fig. 4).