Intermediate phenotypes identify divergent pathways to Alzheimer's disease.

Area of Science:

• Neurogenetics
• Alzheimer's Disease Research
• Cognitive Neuroscience

Background:

• Genetic studies have identified numerous loci associated with Alzheimer's disease (AD) susceptibility.
• The role of these candidate genes in influencing AD intermediate phenotypes, such as cognitive decline and neuropathologic burden, remains largely unknown.

Purpose of the Study:

• To investigate the association between specific genetic variants (SNPs) and Alzheimer's disease (AD) neuropathology and cognitive function.
• To explore how genetic factors influence intermediate phenotypes in AD.

Main Methods:

• Genotyping of 32 single nucleotide polymorphisms (SNPs) previously implicated in AD susceptibility.
• Analysis of 414 subjects with clinical evaluations and brain autopsies from the Religious Orders Study and Rush Memory and Aging Project.
• Regression analyses to assess the relationship between SNP genotypes and measures of AD neuropathology and cognitive function.

Main Results:

• A SNP in the ZNF224 gene (rs3746319) was significantly associated with both global AD neuropathology (p = 0.009) and global cognition (p = 0.002).
• A SNP in the PCK1 gene (rs8192708) was selectively associated with global cognition (p = 3.57 x 10(-4)).
• ZNF224's association with cognitive impairment was mediated by neurofibrillary tangles, while PCK1 influenced cognition largely independently of AD pathology.

Conclusions:

• Findings support the association of ZNF224 and PCK1 loci with AD.
• These results suggest that intermediate phenotypes can enhance the analysis of susceptibility loci in complex genetic disorders like AD.
• The study provides insights into the genetic underpinnings of cognitive decline and neuropathology in Alzheimer's disease.