Yesterday we took a deep dive into what rumination actually is. It is one of the symptoms of depression among other mental illnesses.
We defined rumination as a form of perserverative cognition that focuses on negative content, generally past and present, and results in emotional distress. It’s getting stuck thinking about everything that led to and resulted from a negative experience. It is strongly linked to both depression and anxiety. 
What can the link be between rumination, depression and problems with cognitive functions?
Rumination is thought to absorb a lot of the brainpower available to the person, leaving him or her with less cognitive resources to pay attention and to remember things. When the energy is used to go over and over your thoughts, you’ll have more trouble to bring the attention to the task at hand.
This influences the episodic memory and the working memory. The episodic memory is the recollection of the specific events that happened to you and working memory is the things you remember in the moment to process other information. An example would be when you try to calculate (8 + 14 + 30) /2 = ?, you’ll need to remember the 8 in the first place.
As a result people with depression can experience cognitive problems as lack of concentration, difficulties with understanding, processing and responding to information.
I can tell you that that is very much the case, as it can take me ages sometimes to type up a post. I need to go over and over the information, to hold on to it long enough to process it and to see some kind of connection. On days when I feel better, that whole process goes a lot faster and is less draining for me. And sometimes it leads to shorter posts, like this one.
To break your rumination pattern you would need to redirect your thought process towards something that makes you feel better (like think happy thoughts!) but rumination doesn’t ease this redirection and people get stuck. This can take away your desire to be drawn towards doing something fun or nice for you or someone else.
Rumination can lead to anger and irritability, both symptoms of depression. Rumination is a coping strategy people use to use to help to regulate their emotions. It is just not a very good one. While thinking about when someone (or a situation) did you wrong, due to rumination you keep on thinking that and you become more angry.
Therapy can help you to redirect the thought processes you are stuck in or to digest the past so the rumination won’t be that necessary anymore.