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How can certain diseases and conditions involving the brain change our sense of ‘self’?

When someone doesn't believe their own limb is actually theirs or doesn't believe they are even alive, it can greatly affect their psychological sense of self.

Generally speaking, most people have a pretty solid sense or awareness of “self.” But how does that change when one suffers from certain brain conditions, such as Alzheimer’s disease, Cotard’s syndrome and body integrity identity disorder (BIID), which is a psychological condition that leaves a patient believing a body part isn’t actually theirs?

Science journalist Anil Ananthaswamy examined this concept for his new book, The Man Who Wasn’t There. Ananthaswamy talked with Fresh Air’s Terry Gross about the book and some of what he’s seen that seem to defy what we’d think was “normal” for people and their sense of self.

Ultimately, he explained to Gross that our sense of self isn’t so simple. It is layered and consists of a narrative, bodily and spiritual aspect.

“What it comes down to is this sense we have of being someone or something to which things are happening. It’s there when we wake up in the morning, it kind of disappears when we go to sleep, it reappears in our dreams, and it’s also this sense we have of being an entity that spans time.”

For most of us, when someone asks us who we are, we respond with a narrative approach and share about what we do, how we identify ourselves (a father, a daughter, a wife), and we might share about things that happened in the past or that we hope to happen in the future. But this isn’t the case for some people.

For someone with Cotard’s syndrome, which is a condition that leads people to believe they are actually dead or don’t really exist, that question would get a totally different response. Ananthaswamy described it this way:

It is a complete conviction that they have that they don’t exist. … It’s very, very paradoxical. It poses a great philosophical challenge to people who are trying to understand what it means to say “I exist” or “I don’t exist.” It also makes you wonder about all the other things that we are certain about, like you and I probably are very certain that we exist, well, these people are just as certain that they don’t. So it makes you question about perceptions that arise in the brain and somehow, in this case, the delusion is so complete and so convincing that you really cannot shake their conviction that they are dead.

He says that as far as the brain is concerned with Cotard’s, the part of the brain responsible for internal awareness is compromised, as well as the part of the brain that manages rational thoughts.

For those with BIID, they literally believe that a body part is not theirs, which can be a psychologically debilitating condition. Ananthaswamy talked to Gross about a particular case of man with BIID who ended up having his leg amputated.

I talked to him a few times before the operation trying to find out what it was really that he was suffering from and he really felt like this leg, part of his leg, was not his, it was really something he didn’t want. He would try a whole range of things to make it seem as if he didn’t have it. He would fold his leg and pretend it wasn’t there, he would push it to one side, it really seemed to ruin his life. I remember asking him once, “So what does it exactly feel like?” He says, “It feels like my soul doesn’t extend into that part of my leg.” …

Ananthaswamy pointed out that on the other end of the spectrum, those who have amputations and end up experiencing the sense of phantom limbs give us a more well-rounded understanding that the brain’s perception of our bodies and what’s actually physically there can end up being two different things.

Alzheimer’s disease, on the other hand, really affects our narrative self, the one that can share stories and identify as having certain roles in life.

So because short-term memory formation is impaired, it becomes harder and harder for a person with Alzheimer’s to start having new memories, and once you stop having or forming new memories, these memories don’t get incorporated into your narrative. So, in some sense, your narrative stops forming. As the disease progresses it starts eating away at the existing narrative. It starts basically destroying a whole range of memories that go toward constituting the person that you are. …

Any disease or disorder that affects the sense of self can be debilitating and hard to live with. The ongoing pursuit to understanding more about these conditions is the only way we might be able to relieve some of the struggle that comes with it.

Photo: Flickr user Eugenio Siri

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