Prenatal gyrification pattern affects age at onset in frontotemporal dementia

Abstract

The paracingulate sulcus is a tertiary sulcus formed during the third trimester. In healthy individuals paracingulate sulcation is more prevalent in the left hemisphere. The anterior cingulate and paracingulate gyri are focal points of neurodegeneration in behavioral variant frontotemporal dementia (bvFTD). This study aims to determine the prevalence and impact of paracingulate sulcation in bvFTD. Structural magnetic resonance images of individuals with bvFTD (n = 105, mean age 66.9 years), Alzheimer's disease (n = 92, 73.3), and healthy controls (n = 110, 62.4) were evaluated using standard protocol for hemispheric paracingulate sulcal presence. No difference in left hemisphere paracingulate sulcal frequency was observed between groups; 0.72, 0.79, and 0.70, respectively, in the bvFTD, Alzheimer's disease, and healthy control groups, (P = 0.3). A significant impact of right (but not left) hemispheric paracingulate sulcation on age at disease onset was identified in bvFTD (mean 60.4 years where absent vs. 63.8 where present [P = 0.04, Cohen's d = 0.42]). This relationship was not observed in Alzheimer's disease. These findings demonstrate a relationship between prenatal neuronal development and the expression of a neurodegenerative disease providing a gross morphological example of brain reserve.

Keywords: behavioral variant frontotemporal dementia; cingulate; paracingulate; sulcation.

Figure 1

Cingulate and paracingulate sulci identification and measurement. A 62-year-old male with probable bvFTD displays a leftward pattern of paracingulate asymmetry (“double/single”). (A) Sagittal slice (left) of the left hemisphere 3 mm left of the midsagittal line displaying a prominent left PCS (red) and CS (green). (B) Sagittal slice (left) of the right hemisphere 3 mm right of the midsagittal line displaying an CS (green) with absence of a rightPCS.

Figure 2

Age at symptom onset by right hemisphere PCS presence in bvFTD. Black dots represent study individuals. Black lines represent group mean age at symptom onset.