Neurological Constellations: SDAM. The curious case of missing personal memory

How many types of memory do you think there are? Give it a guess.

Growing up I thought there were two:

• Facts you've memorized (sematic memory)

• Things you've learned to do (procedural memory)

It turns out there's actually 2 major categories, at least 7 basic types, and on top of that each type isn't isolated. For example, there's a crossover memory type called Source Memory, which is where you can remember not just a fact but also where/how/when you learned it to begin with - because these memory systems aren't entirely discretized.

But all of that is way too much detail already. What I want to talk about here is one specific type of memory, and what not having it looks like. Episodic or autobiographical memory could be considered "personal experienced" - so being able to put yourself in your own shoes during your 10th birthday, or being able to remember the narrative of a movie you watched.

In both of those examples (the birthday and the movie) you can almost re-live the experience when using episodic memory. Without it you have to rely on semantic memory, or facts about what happened. For example on your nephew's 10th birthday:

• The birthday cake was next to the pool.

• Uncle Bob had had too much drink.

• He was trying to cut the cake, but lost his balance and stumbled forward.

• He fell face first onto the cake.

• While saving himself from hitting the floor, he forgot about the pool, and fell in.

• No one cared about the lost cake, because the whole scene was too funny to be grumpy about.

There isn't much narrative to that story is there? Instead of describing a meaningfully personal scene, it's just structured facts without experiential context. That's SDAM in a nutshell. Here's a richer episodic description of the same event told through the lens of someone who actually has those episodic memories and can re-experience an event:

It was the middle of the day, in the mid-July Florida heat. We'd gathered for Tim's 10th birthday, Nan had made a point of getting him a red racing car cake because he was going through a phase of being obsessed with racing cars. My brother Bob had, not unusually, had been at the Coors, and was already making a fool of himself just by how loud he was being. To be fair he was trying to play games with my niece and nephew, so for once no one really minded. Unfortunately, when it was time to cut the cake, my nephew insisted that Bob do it... I tried to intervene, the cake was by the pool, the floor was slippery, and he was already wobbly enough. But telling him he couldn't do something while in that state was a pretty lost cause.

So I just handed him the knife and begged him to be careful. It didn't take long for shit to hit the fan, while walking towards the cake he hit a pool noodle - not exactly what I'd called a barrier to mobility - and that was enough to send him careening towards the cake.

Somehow he remember he had the knife in-hand, and did this hilarious dance of keeping it as far from his body and face as he could. That also meant he had to hope of catching his balance. One foot was now left on the ground, and he'd reach a 45 degree angle (and the cake-table) at about the same time. I wish I'd gotten a photo of the look on his face. In under half a second he both hit the cake with his face, and twisted his body to try and avoid it... putting him even more off balance. There was only one way this was going to end.

literally every single part of that racing car cake ended up in the pool, as a layer of icing on the water. And every single family member burst out laughing simultaneously, as though they had been holding their collective breath for fear that things may have ended in injury. Trading that $20 cake for a million dollar memory was absolutely worth it.

See the difference? There are technically facts littered throughout the story of Bob's Cake Disaster, but it's all much more personal, much more narrative, and much more real.

What this all means for someone with SDAM is that they life without a narrative history. It's tough to form meaningful emotional bonds when by the following day your recollection of an event might be boiled down "Bob got drunk and fell in the pool". By the day after that it might just be "Bob fell in the pool", and other people will have to remind you how and why he fell in. The event exists as nothing but a cold fact in your semantic memory.

As a consequence, people and your relations to them also exist almost entirely as facts.

How often do random facts you learned about in middle school, high school, university (or any other time in your life) just pop into your head? Do you suddenly remember the Pythagorean Theorem and what it's used for, or that the assassination of Archduke Ferdinand was the what triggered World War 1? Probably not. And for someone with SDAM, who has personal-relationships exist primarily as facts, said "facts" don't pop into their heads.

This makes maintaining relationships particularly challenging: most people engage in something called social rehearsal, the unconscious strengthening of bonds through shared recollections ("Remember when we...?"). For those with SDAM, these spontaneous reminiscences don't happen naturally. What others do automatically, we must implement consciously and methodically - setting calendar reminders to check in with friends, keeping relationship journals, or creating structured social routines that don't rely on episodic memory triggers.

This makes maintaining relationships (personal, familial, professional and otherwise) tricky, as just like with facts if you don't actively go looking for them for some reason they are easily forgotten or ignored. Until that relationship fades away.

My personal experience with this is that I don't remember my own wedding, beyond what the photos on wall can tell me about the day; I can't remember playing in back garden as a kid; and I can name (and nothing more) maybe 2 or 3 people I was friends with in school.

As a side-project I'm writing a story that tries to portray the experience of living this way, but it's tricky explaining the lack of something you've never experienced yourself. The closest I've gotten so far is this: for every conversation you have, you're furiously taking down notes about everything that's going on. But as soon as the conversation ends, you become your notes... then some dickhead tears you into tiny pieces and drops you on the ground. Somehow in your torn-up state you have to pull yourself back together, but there's so much that went into that conversation that the most you can manage to identify about your own fragments are a few simple distinct facts - and so those are the pieces of you that you pull together before the rest of you is swept up in the wind.

I've come up with a couple of coping mechanisms for living with SDAM, including the challenge of living without a narrative self-identity, but each one of those deserves its own post. One approach that's been particularly powerful involves creating "value tokens" - physical objects that serve as tangible anchors for my core values and identity when memory alone can't maintain that continuity. For example, I wear an eye-covered ring as a reminder to try and listen to all the voices, perspectives, and drives that exist simultaneously in my head.

For now I hope that that gives a glimpse into this fascinating neurological condition. Thanks for reading, and remember: do mind me, because everyone is worth listening to.