I think it is depression, which affects cognitive abilities negatively.

Most of my stories are about cats, and this one is no exception.

Slightly over a year ago, I started fostering cats. I was in my last suicidal depression and my cats contributed to my survival - when I wanted to OD, I thought through the consequences and realized that the cats would die from starvation because I did not have any friends or family to check on me (I lived alone) for days and days.

Ellen, the head of the rescue agency from which I acquired the cats advised me on feeding the cats in the manner that is optimal for their health and longevity. Ellen has been running the rescue agency for two decades and close to 1K of stray cats have found homes through her, and she herself keeps several very old cats (it is amazing how long cats can live with proper care).

So she told me: grain-free high quality wet food only.

That did not ring any bell for me, but I trusted Ellen and went on buying high quality food.

Fast forward almost a year, no depression and in good spirits. One day, I ran out of high quality wet food I buy from Amazon, and I went to my local grocery store hoping to find some high end food. All the food at the local grocery store was horrible, with ingredient lists consisting of 10-20 unpronouncable names.

Then it rang a bell for me: almost 20 years ago, I and another girl, Kathy, were house-sitting for somebody and had the task of feeding their cat. Kathy said that the cat owners (who are very frugal people) were feeding the cat horrible cheap food and went to Whole Foods to buy high quality food for the poor animal. AT THAT TIME I THOUGHT THAT KATHY WAS COMPLETELY CRAZY.

So at my grocery store when I saw that there was nothing good for the cats, I remembered Kathy and even wrote a short story about her (cat feeding was not the only interesting interaction I had with Kathy).

So the ability to connect related events is a cognitive ability that goes away when you are depressed, in my experience. I really should have remembered Kathy when Ellen first told me about high quality grain-free protein food - I should have registered that no, Kathy was NOT COMPLETELY CRAZY after all. But I made no connection at all, because a depressed mind ruminates and is unable to make those connections.

Now I am not depressed and I remember all sorts of things and make connections between things easily and effortlessly.

In my personal experience, the thing that is to blame is rumination, and depression is notorious for causing rumination. Rumination is like gas in that it fills any space available to it - it can basically fill the entire brain/mind, not leaving any space either for processing new information or for making connections between new information and the contents of your long term memory. It is insidious in that it closes off opportunities for interacting with the world around us. I do not know how to best phrase it - it is basically life poisonous grey-colored smoke that fills your brain and disables your ability to think up an interesting thing to say. And it creates some sort of a vacuum bubble that removes your connection not only to the outside world, but to the contents of your own memory accumulated over the whole course of your life.

I am sorry this was so long-winded!