Cognitive impairments stack in a multiplicative rather than additive way. This means that in instances where conditions are combined—e.g. chronic depression combined with poverty—there is a real danger that cognitive function reaches a near-zero or severely impaired state. This is because each layer of cognitive burden doesn’t simply add to the previous one; it compounds and exacerbates the others, creating a situation where the total capacity to engage with the world, make decisions, or think clearly diminishes exponentially.

Here’s a bit more on how that works:

• Chronic Stress (from poverty, for example) taxes cognitive resources, like working memory, attention, and decision-making capacity. This reduces the ability to handle complex tasks, problem-solving, or even basic daily decisions.
• Depression already impairs cognitive function—especially in areas like memory, concentration, and executive function. It makes it hard to focus, plan, or even recognize the need for action.

When these two conditions interact, they create a vicious feedback loop where:

1. The cognitive deficits from depression make it harder to deal with the daily pressures of poverty (like managing finances, navigating bureaucracy, etc.).
2. The cognitive depletion caused by poverty (decision fatigue, chronic stress, etc.) makes depression symptoms worse, further degrading cognition.

This leads to a scenario where cognitive function can be so impaired that simple tasks—like remembering appointments or managing a household—become incredibly difficult, and executive function can be nearly nonexistent. It's not just that the cognitive load is heavy; it's that the person cannot even process or organize that load properly.

In extreme cases, the cognitive load is so overwhelming that it could be as if the person’s mental capacity is nearing a state of near-zero functioning, because each new stressor or cognitive burden doesn’t just add to the previous stress—it compounds it. So it’s not simply exhaustion—it’s a breakdown of the systems that allow thinking, decision-making, and even emotional regulation to function.