This study proposes using accumulated neurotoxicity, defined as the time integral of A{beta} oligomer concentration, as a biomarker for neuronal aging. A relationship between biological age and accumulated neurotoxicity is proposed. Numerical analysis guided the development of a new analytical solution linking the biological and calendar ages of neurons. The effects of A{beta} monomer and oligomer half-lives - key indicators of proteolytic efficiency - on biological age are examined. Both constant and age-dependent (exponentially increasing) half-life scenarios are considered. The findings indicate that increasing the half-life of A{beta} monomers and oligomers with age accelerates biological aging. Reducing A{beta} monomer production is shown to slow biological aging, with a linear relationship established between these two quantities. Additionally, biological age is found to depend linearly on the half-deposition time of A{beta} oligomers into senile plaques.