What caused strange change in behavior?

Posted: August 18, 2014

A middle-aged woman who had been a regular customer at a neighborhood store started behaving strangely.

At first, the changes were subtle. But over the course of a month, the store owner noticed that when the woman came in every morning to buy her usual drink and newspaper, she seemed more withdrawn and preoccupied. It also became apparent she was neglecting her personal hygiene.

Finally, one morning, the customer arrived completely confused. She began screaming and the shop owner called 911. She was taken to the emergency room.

The ER doctor ordered a full battery of tests.

A CT scan of her head showed no troubling signs.

But blood and urine tests showed she was dehydrated and had some sort of bacterial infection. Her doctors believed her strange behavior and confusion may have resulted from her urinary tract infection. It is not clear why bacteria coursing through the bloodstream causes a change in mental status, but it is quite common.

Because the woman was behaving so erratically, however, her doctors also asked a psychiatrist to evaluate her.

The patient could not say what day, month, or year it was and could not recall the name of the hospital. Her husband told the psychiatrist the patient had been treated for depression and psychosis but had run out of her medication.

For at least a month, the patient had not been sleeping or eating well, her husband said.

The staff was able to contact the psychiatrist who had treated the patient before. He confirmed that she had been diagnosed with depression and listed the medications that had been prescribed.

Given this history, the doctors decided the main cause of her confusion was probably due to a psychiatric condition rather than the urinary tract infection and dehydration. She was admitted to the psychiatric ward and treated for depression and psychosis. The medical team remained involved, consulting about her medical management (intravenous medications and fluids).

By the fourth day, she was thinking more clearly. When the patient's husband and their children came to visit, however, she was overheard arguing loudly with them.

At one point, she shouted, "I don't want that man here!" She also denied knowing her children. The staff responded and security escorted the family out of the hospital.


When her family spoke to her on the phone, she sounded like her old self. But when they visited her in the hospital, they told the social workers that she was "like a different person."

Given the hostility, her husband was unwilling to take her home.

After the patient had been in the hospital for a week, her husband came again to visit. As he was about to leave, he began crying and told the nurse he was worried his wife was getting worse.

"She doesn't even know me," he said.

The social workers and psychiatrists met, wondering whether they had missed something. More laboratory tests were ordered and a brain MRI was done.

All of the results came back normal.

A family meeting was scheduled. In addition to the patient, her husband and children, several social workers, nurses, house staff, and the consulting psychiatrist would attend.

The patient agreed that it would be a good idea to meet and discuss a plan for her return home and psychiatric treatment as an outpatient. But as soon as her husband arrived, the patient balked.

"What's he doing here?" she asked.

"I'm your husband, remember?"

"No you're not. You look like him but you are NOT him." Her husband pulled out wedding photographs and snapshots of their children.

"You look like him, but you do not seem like him," the patient said. "The children look exactly like mine but I am sure you are not my husband. Why are you pretending to be him?"

At that moment, the diagnosis revealed itself.

The patient had Capgras syndrome, a rare psychiatric diagnosis believed to have some as-yet unidentified neurobiological basis.

Something in the brain creates a disconnect so people physically recognize someone they know but cannot recall any emotional ties.

As a result, patients believe family members are imposters.

The woman was transferred to a longer-term psychiatric unit for treatment with antidepressants and antipsychotic medications. Within several weeks, her symptoms resolved and she was able to return to her family.

Karen Mechanic is a psychiatrist at Fox Chase Cancer Center.

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