Researchers have made strides in understanding why Alzheimer’s disease progresses to dementia in some people, but not in others. A study from teams in Belgium and the UK sheds light on the role of brain immune cells. Their findings, published in Nature Medicine, indicate a significant role of microglia in the disease’s progression.

Role of Brain Immune Cells

Alzheimer’s disease involves the accumulation of proteins like amyloid plaques and tau tangles. Yet, these changes do not guarantee the onset of dementia. The study examined brain tissue from various adults, focusing on microglia, which serve as the brain’s immune defense. It was observed that microglia react differently as Alzheimer’s unfolds.

Initially, microglia enter an inflammatory state linked to amyloid plaques. These plaques consist of protein clusters that can interfere with cell function. As the disease advances, microglia transition into a different state that correlates with tau buildup and brain damage.

The study suggests this shift in microglial states could play a pivotal role in determining whether Alzheimer’s brain changes culminate in dementia.

Dr. Steve Allder, a consultant neurologist, commented on the significance of investigating immune responses in the brain alongside traditional focuses on amyloid plaque removal. Enhancing protective immune mechanisms may help delay or prevent Alzheimer’s symptoms.

Variations in Alzheimer’s Resilience

Not all individuals with Alzheimer’s pathology exhibit similar outcomes. Some older adults with amyloid plaques do not develop dementia, bypassing the later immune response stage linked to disease progression. Meanwhile, cognitively healthy centenarians sometimes engage in this immune response without significant tau buildup.

This implies that resilience might depend not only on the absence of disease features but also on the brain’s adaptive responses. Professor Mark Fiers, the study’s corresponding author, emphasized that understanding these resistance mechanisms could guide future prevention strategies.

Future Alzheimer’s treatments may benefit from these findings by targeting microglial states and pathways like TREM2 to enhance brain resilience rather than exclusively focusing on reducing plaques. Niels Plath, Muna Therapeutics’ chief scientific officer, expressed enthusiasm about exploring new therapeutic avenues based on these insights.