It’s Not Always Dementia. Here’s What to Know

Your aging parent is suddenly acting more confused, distracted, forgetful, and moody. You brace yourself for the feared diagnosis: Is it dementia, or worse … Alzheimer’s?

Maybe. But most seniors showing these symptoms “out of the blue” are likely experiencing a far different ailment: delirium, commonly caused by an infection.

Each year, thousands of cases are misdiagnosed as dementia.

“Delirium (officially called acute toxic metabolic encephalopathy) can mimic many of the same symptoms as a dementia. The key difference is rapidity of symptom development” says Dr. Christian Camargo, a neurologist who specializes in the cognitive side (e.g., memory, language, problem-solving, decision-making, perception) of human brain health and illness at the University of Miami Health System.

According to Dr. Camargo, delirium can be characterized by symptoms including:

  • Confusion
  • Inattention
  • Unusual sleepiness
  • Sudden mood changes
  • Inability to concentrate
  • Hallucinations, abnormal thoughts or beliefs.

There are two major differences between dementia onset and delirium symptoms: How fast or slow the onset occurs, and how long it continues or worsens.

“Delirium symptoms can appear suddenly,” adds Dr. Camargo. “They might surface over hours or a few days. If it was a dementia due to a condition such as Alzheimer’s Disease or Lewy Body Disease, such symptoms would start slowly and become chronic and progressive, advancing over time.”

Why would an infection cause this?

The human body only has a certain amount of resources, says Dr. Camargo. As we age, our bodies have fewer tools to fight illness. If we take resources away from one part of the body, it is harder to compensate and perform normally in the other parts, including in our brains.

“When faced by an infection, our bodies send disease-fighting and metabolic resources to where the problem is. We’re sending out the available troops to fight in another land,” he says. “Younger adults are resilient. We may become tired. But as we get older, we have fewer resources to begin with. The brain can become starved, and delirium can result.”

Even changes in body temperature can affect how our brains function, he adds. It stands to basic logic.

“When we’re 75 or 80, we aren’t able to go run a marathon or even a 5K, as easily as we did when we were 40. The body has less reserves of everything and power to draw from. The same goes for any type of infection or injury we might face.”

When you add the fact that different causes of delirium may also disrupt chemical activity of the brain, release toxic substances into the bloodstream, and alter electrolyte levels in the body, it becomes clear that a less resilient brain falls victim to delirium.

This is precisely why, adding to the diagnostic confusion, one of the major risk factors for delirium is in fact an underlying dementia. “While having an underlying dementia and being older are the greatest risk factors for delirium, not everyone who has delirium has dementia,” says Dr. Camargo.

Ensuring an accurate diagnosis

With the number of people with dementia expected to increase over the next 30 years, comprehensive and accurate screening has become more important than ever. Dr. Camargo advises any family to ask questions of their providers. Ensure screening is more than a set of one-day neurological tests.

“The only way to accurately diagnose a progressive disorder is to make progressive assessments,” he shares. “Multiple evaluations over time help us to see what is causing the cognitive symptoms. It takes studying the small things, and truly engaging with the patient.”

The University of Miami Memory Disorders Center (UM-MDC), where Dr. Camargo practices, is one of 13 memory disorder clinics partly supported by the State of Florida Department of Elder Affairs, Alzheimer’s Disease Initiative (ADI). The program uses a collaborative team of experts from the Department of Psychiatry & Behavioral Sciences Center on Aging and the Department of Neurology.

“At least a handful of patients a day at emergency rooms across the country and world may be misdiagnosed,” he says. “Doctors are doing their best but are not often trained in the subtleties. They are seeing the patients at only one point in time.”

For these patients, as well as those with memory issues outside of the context of delirium, “If your loved one is experiencing memory problems, they may benefit from seeing a memory specialist such as a cognitive neurologist to evaluate potential causes.”

If it is indeed a delirium, he says, that in itself is its own serious condition. The cause of the delirium – whether it is an infection, medication, electrolyte imbalance, or otherwise – needs to be diagnosed and treated appropriately and quickly.

Learn more about treatments for Alzheimer’s disease and dementia.


John Senall is a contributing writer for UMiami Health News.