Early life functional advantage coupled with accelerated aging: The case for antagonistic pleiotropy in Huntington's disease

Abstract

Recent findings suggest that neurodevelopment plays a critical role in Huntington's Disease (HD) pathogenesis. This review integrates data from human studies of children and young adults at risk for HD (the Kids-HD study) with the theory of antagonistic pleiotropy (AP), which posits that genes promoting early-life advantages may confer late-life risks. Longitudinal imaging of gene-expanded (GE) children and adolescents shows that mHTT is associated with larger cortical volumes, enhanced surface morphology, and superior cognitive performance—decades before clinical onset. However, this early benefit is paired with accelerated striatal decline, suggesting that mHTT drives an early “ability” that transitions into a “liability.” Vertex-wise analyses reveal cortical enlargement in regions with dense glutamatergic projections to the striatum, implicating excitotoxicity as a mechanism linking development to degeneration. This pleiotropic pattern parallels evolutionary models, where genes like HTT may have an evolutionary trade-off where genes supporting growth and reproduction are favored over those that serve long-term somatic maintenance, leaving cells with diminished repair capacity and resulting in an accelerated aging process. Altogether, these findings support a novel framework in which mHTT accelerates both brain maturation and neurodegeneration, offering new insights into HD biology and therapeutic targets.

Plain language summary

Although Huntington's Disease (HD) is conceptualized as a progressive degenerative brain disease, many studies have shown that the beginnings of the disease may occur during brain development. The gene that causes HD is known to be important in helping to shape brain development. This article reviews findings from human studies of children at risk for HD and discusses how the gene may be driving the development of a superior brain early in life that is built in such a way in which it is then vulnerable to accelerated aging later in life. This is termed “antagonistic pleiotropy” in which a gene can create both advantage and disadvantage. This process is also discussed in the context of evolutionary biology where antagonistic pleiotropy is a leading theory of both human brain evolution as well as aging.