'Memory of a Killer' Explores Alzheimer's Connection to Killing—How it Actually Affects the Brain

Alzheimer’s disease affects more than 7 million people in the United States with symptoms including memory impairment and a loss in functionality. But can Alzheimer’s disease also change someone’s mind to the point where they don’t recall committing a major crime?

Crime drama Memory of a Killer asks this chilling question in its premise: Patrick Dempsey plays a hitman who begins losing his memory and sense of self due to a diagnosis of early-onset Alzheimer’s disease. But the real science is likely more nuanced.

Alzheimer’s disease and related dementias are complicated illnesses. The causes still aren’t entirely understood.

“Alzheimer’s disease is the most common form of dementia, a clinical term for a neurological condition that impairs one’s ability to function independently," Dr. Keith Vossel, a professor of neurology at the University of California, Los Angeles, tells A&E Crime + Investigation.

Symptoms generally start with issues involving vocabulary recall and short-term memory loss in mild cases, leading to a loss of full functionality as decline progresses, Vossel says.

Similarly, a distressing aspect of Alzheimer’s disease is how slowly yet inescapably it affects sufferers once diagnosed. “Dementia is gradual and pervasive, not a convenient, selective loss of memory like television often portrays,” says licensed forensic psychologist Dr. Dana Anderson.

While Alzheimer’s disease usually occurs in individuals over the age of 65, there are early-onset cases that prove similar to the one exhibited in Dempsey’s hitman—with a big difference.

“Symptoms include language or visuo-spatial symptoms, with variable degrees of memory loss," Vossel says. "Rarely, early-onset Alzheimer’s disease presents as a behavioral variant with impulsivity and personality changes.”

But even in these exceptional cases where behavior alters due to neurological changes, Anderson concurs that, unlike the memory issues shown in Memory of a Killer, “Younger individuals may first show problems with work performance, planning or judgment rather than obvious memory loss.”

Despite Alzheimer’s disease being a heartbreaking ailment, it usually won’t negatively affect an individual’s personality or sense of judgment in earlier stages of diagnosis. However, Vossel acknowledges, “Patients with Alzheimer’s disease could conceivably get involved in illicit behavior if it involves trusting others or complicated legal scenarios—not due to changes in morality, but due to their changes in understanding of context.”

Anderson agrees with Vossel’s assessment.

“As Alzheimer’s disease or related dementias progress, some people develop personality or behavioral changes such as irritability, apathy, emotional blunting, reduced inhibition or difficulty regulating emotions,” she says. “In some cases, neurodegenerative conditions can impair judgment and impulse control, leading to behavior that appears inconsistent with prior values.” But she clarifies that behavioral changes caused by Alzheimer’s and related dementias will vary by individual, especially regarding the advancement of the illness and which brain regions it affects.

Vossel also says that, theoretically, an individual diagnosed with Alzheimer’s disease could lack recall of a crime if they already possessed a sociopathic personality. However, given the relatively small percentage of people diagnosed as sociopaths, he emphasizes that for most Alzheimer’s disease patients, “Events with high emotional salience such as witnessing or participating in a major crime would be remembered, at least the gist of the events.”

There have been several instances of people claiming not to recall crimes they committed. But “from a forensic standpoint, memory and intent are separate issues," Anderson says. "A person’s ability to remember an event afterward is different from their mental state at the time the act occurred. Remembering less later does not eliminate intent at the time of the behavior.”

As part of her job, Anderson conducts assessments on defendants who claim they suffer from a neurodegenerative disease.

“Courts approach these questions on a case-by-case basis,” she explains. “When a defendant reports memory loss related to cognitive decline, courts rely on objective evidence. This typically includes medical records, collateral information and a forensic psychological evaluation.”

Vossel says that rigorous evaluations are needed in the criminal justice system to determine culpability for someone with cognitive decline.

“Accountability in these cases requires assessment for changes in judgment, impulse control, insight and personality that could impair decision-making,” he says. However, ultimately, Vossel agrees that Alzheimer’s disease patients in the mild or early stages—as in Memory of a Killer—would be held responsible for criminal actions, especially if they understood the difference between right and wrong.

As horrible and debilitating as Alzheimer’s disease can be, even in the early-onset variety, the persistent memory loss of Dempsey’s hitman in Memory of a Killer would likely not advance as quickly in real life, and a diagnosis of early-onset Alzheimer’s disease alone wouldn’t lead to leniency in the justice system.

“Dementia can affect memory, but it doesn’t usually erase only the inconvenient parts of someone’s life,” Anderson reiterates, adding, “real cognitive decline shows up everywhere, not just around a crime.”

Though symptoms gradually affect Alzheimer’s disease patients, Vossel does admit, “Sense of culpability could be affected if an action arises from a cognitive or behavioral deficit—for example, shoplifting due to genuinely forgetting that an item had not been paid for.” Such examples are rare, however, and usually involved minor crimes rather than major ones like homicide.

Given too how organized someone would need to be to plan and follow through on a crime, it’s more fiction than fact that serves as the basis for Memory of a Killer. There is also the amount of cognitive ability it takes to plan and organize a crime, something someone with dementia may struggle with. Still, Anderson says it's an interesting premise for a show.

“Real dementia doesn’t conveniently turn a professional killer into someone who only forgets the murders,” she says.