Legendary singer Tony Bennett, who died on July 21 in New York at age 96, had a history of health issues over the years, culminating in his seven-year battle with Alzheimer’s disease.

Although no cause of death was indicated in the announcement of Bennett’s passing, his publicist, Sylvia Weiner, mentioned his 2016 Alzheimer’s diagnosis.

The Alzheimer’s Association, with which Bennett partnered to raise awareness and funds for the disease, also released a public statement.

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“The Alzheimer’s Association joins the world in mourning the loss of Tony Bennett, a great friend and champion of the cause,” said Joanne Pike, president and CEO of the Alzheimer’s Association in Chicago, Illinois, in the statement. 

“For decades, Tony inspired the world with his music and, after being diagnosed with Alzheimer’s disease, he continued to use that powerful voice to make a very real difference in inspiring action and change.”

Several neurology experts shared with Fox News Digital the key points people should know about late-stage Alzheimer’s — and its potentially fatal complications.

Alzheimer’s: Most common form of dementia

Alzheimer’s disease is a cognitive disorder that causes damaging proteins to build up in the brain, according to the Mayo Clinic.

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Around 6.5 million people 65 and older are living with Alzheimer’s in the U.S., with the disease comprising up to 70% of all dementia cases.

Over time, the disease causes brain shrinkage and kills brain cells, resulting in a gradual cognitive decline. 

There is currently no cure for Alzheimer’s, although a new drug called Leqembi, which works to remove plaque from the brain, recently received FDA approval.

Early signs of Alzheimer’s include episodes of short-term memory loss. It eventually leads to memory loss and an inability to function.

There is currently no cure for Alzheimer’s, although a new drug called Leqembi, which works to remove plaque from the brain, recently received FDA approval.

“The drug has been shown to slow down disease progression in the early stages of the disease,” Dongxu Sun, PhD, an Alzheimer’s research expert in San Francisco, told Fox News Digital. 

“Leqembi, like all other plaque-removing drugs, can lead to side effects such as brain swelling and bleeding because it removes plaques through enhancing neuroinflammation.”

Late-stage Alzheimer’s disease

During the advanced stages of Alzheimer’s, patients experience severe cognitive decline, according to Dr. Rehan Aziz, a geriatric psychiatrist at Jersey Shore University Medical Center in Neptune, New Jersey and associate professor of psychiatry and neurology at Hackensack Meridian School of Medicine.

During late-stage Alzheimer’s, patients experience severe cognitive decline. (iStock)

“In this stage, individuals may lose the ability to recognize familiar people, including family members and friends,” he told Fox News Digital. 

“They may have difficulty communicating their needs.”

People with late-stage disease often need help with routine activities like getting dressed, eating and cutting food, showering, combing their hair or brushing their teeth, using the toilet and even walking, the doctor said.

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They may also experience behavioral and psychological changes.

“Individuals can develop a number of psychological symptoms, including apathy, depression, difficulty sleeping at night and aggression,” Aziz said.

These patients often require 24-hour care, either at home with the appropriate services or in a skilled nursing facility, the doctor said.

Over time, the disease causes brain shrinkage and kills brain cells, resulting in a gradual cognitive decline.  (iStock)

“Caregivers have high rates of depression, as well as increased chances of becoming physically sick,” he warned. 

“It is important that caregivers take care of themselves and seek support.”

Aziz often refers caregivers to Alzheimer’s support groups as well as to mental health clinicians if needed, he said.

When does Alzheimer’s become fatal?

Unlike cancer or Lou Gehrig’s disease, Alzheimer’s disease is not a direct cause of death, according to Dr. Arif Dalvi, director of the Memory Disorders Center at St. Mary’s Medical Center in West Palm Beach, Florida.

“However, as the disease state progresses, the patient’s ability to take care of themselves, even with help, declines considerably,” he told Fox News Digital. 

“This general deconditioning leads to complications that are directly responsible for death.”

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The average life expectancy for someone with Alzheimer’s disease is around 8-10 years, according to the Alzheimer’s Society. Longevity is shorter for those who are diagnosed in their 80s or 90s.

“Based on a person’s health condition and lifestyle, some patients decline quickly and succumb to the disease within a few years — while others can live for many years after diagnosis,” said Sun of San Francisco. 

Typical cause of death for Alzheimer’s patients

In addition to causing memory loss, Alzheimer’s also leads to a decline of the immune system, the cardiovascular system and others, said Sun.

“These declines can lead to the development of fatal complications like aspiration pneumonia, stroke or heart disease,” he explained.

Patients with late-stage Alzheimer’s often require 24-hour care, either at home with the appropriate services or in a skilled nursing facility. (iStock)

Dalvi commonly sees Alzheimer’s patients succumb to infections, which can be fatal.

“A combination of disease progression, general debility from aging and decline in hygiene due to an inability to take care of themselves leads to susceptibility to infections,” he explained.

“Pneumonia is the most common, although urinary tract infections also are seen fairly often,” he continued. “In the debilitated person, this can lead to sepsis and death.”

“Some patients decline quickly and succumb to the disease within a few years, while others can live for many years after diagnosis.”

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Other potential causes of death include malnutrition as a result of not eating or having trouble eating, accidentally inhaling foods or liquids or falls/accidents caused by weakness or wandering.

That’s according to Dr. Jasdeep S. Hundal, a board-certified clinical neuropsychologist and associate professor of psychiatry and neurology at the Hackensack Meridian School of Medicine in New Jersey.

Caring for people with late-stage Alzheimer’s

Maintaining adequate nutrition and hydration is extremely important for those with advanced dementia, Dalvi, said, as it supports general well-being and immune function. 

Because patients with Alzheimer’s can forget to eat, the doctor said their weight should be monitored on a regular basis.

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“Feeding should be supervised, as difficulties with swallowing can lead to aspiration pneumonia,” he warned. 

“Minimizing unnecessary medications and regular medication review is also important.”

Additionally, he emphasized the need to minimize fall risk. 

“It is also important to take care of the emotional needs of the caregivers and family during the late stage of the condition,” Dalvi added.