The effect of depressive disease on the pathology of Alzheimer`s disease

Alzheimer`s disease (AD) is a progressive degenerative disease characterized by cerebral pathology and behavioral symptoms. The brain pathology of AD causes several damaging changes in the brain, including extracellular accumulations of beta-amyloid in amyloid plaques. Furthermore, AD is characterized by deficits in cognitive functions accompanied by behavioral and emotional disorders.

In AD, immune activation of microglia cells occurs, which affects in diverse ways the pathogenesis of the disease and is associated with its worsening.

Major depressive disorder (MDD) is a neuropsychiatric disorder with numerous contributing factors – genetic and environmental – that significantly affect the physical and mental health of those who suffer from it.

There are two primary relationships between AD and MDD: In both, chronic stress is a risk factor and immune activation transpires.

The research I conducted was based on the aforementioned relationship between the diseases. I investigated the effect of depressive disease on the behavioral pathogenesis of Alzheimer`s disease through a series of behavioral tests on four groups of mice: wildtype mice (WT) control, WT stress (WT mice exposed to chronic stress to induce depression), transgenic mice (TG) control (transgenic mice for AD) and TG stress.

In this study, we saw that exposure to stress triggered a depressive phenotype and caused injury and escalation of the injury to Alzheimer`s mice, and in particular aggravated the impairment of behaviors dependent on the prefrontal lobe, which is associated with the early stages of AD. In contrast, hippocampus-dependent behaviors were not affected by exposure to stress.