Cognitive Dysfunction in Depression

I have Major Depressive Disorder (MDD). It's a battle I have to fight everyday. I'm proud to say I haven't lost yet. It's hard to make family and friends understand that this is a serious struggle. The symptoms commonly associated with MDD are changes in sleep, appetite and energy, combined with a lack of interest, low self-esteem and hopelessness. This gives MDD the image of an emotional attitude, something you can change or just snap out of. That's not it at all.

I like to compare MDD to the weather. It's always there, it changes, you can't control it, but with skill, you can predict it and take precautions. It's like a fog that rolls in and clouds your outlook on life. It's dark and difficult to see through. It could last anywhere from hours to months. Then, a beam of light or a gust of wind dissipates it and the world looks brighter again. So asking why can't they snap out of it is like asking why is the sky blue.

I'm hoping recent research on the symptoms of MDD will help lift the stigma. The old myth that depression is purely a mood disorder is slowly being overturned. Research has shown that patients with MDD can also suffer from cognitive dysfunction. What's that you say? It's that foggy feeling you get in your brain. You can't concentrate, you forget what you've just read and processing information, let alone doing anything is hard. It's not an excuse give up and be lazy. It's a frustrating difficulty that we have to learn to work with.

What is cognition?

Cognition is not academic skills. Academic skills include knowledge about specific subjects like math or philosophy. Cognitive skills refer to thinking and how you interact with your environment, things everyone does everyday. Cognition allows you to perceive, acquire, understand and respond to information through abilities such as attention, memory, information processing, problem-solving and organization. These abilities are essential to function in our society. Cognitive dysfunction is when these abilities are impaired.

Recent Findings

Cognitive dysfunction can have a huge impact on the quality of life. Until recently, changes in cognitive function weren’t linked to the diagnosis of MDD. Using well-developed, objective cognitive function tests, Cogstate showed that the prevalence of cognitive dysfunction is almost 50% across a group of MDD participants. Those with cognitive dysfunction have lower productivity levels compared to normals and those who were depressed but cognitively normal. These cognitive symptoms are stubborn too. They don't come and go with the fog of a depressive episode. They persist through the better times too. Researchers believe that cognitive symptoms may be more debilitating than the physical symptoms of MDD, possibly the underlying cause of disability.

Parts of the Brain Involved

Areas in the brain involved in cognition overlap and communicate with regions responsible for mood and emotion, namely the frontal-limbic circuitry and the hippocampus. The frontal part of the brain is responsible for cognition while the limbic system handles emotion and the hippocampus manages memory storage and processing. These areas communicate via neurotransmitters that I'm sure you are familiar with; serotonin, norepinephrine and dopamine. After all, these are what our medications aim to increase. A decreased level of serotonin explains the lack of motivation and will power that characterizes depression. Lower levels of norepinephrine decrease abilities to concentrate, while decreases in dopamine take away enjoyment. MDD is not just low levels of neurotransmitters, otherwise our anti-depressants would have put us all in complete remission.

Eureka!

Recent research has determined that our brains are structurally different from people who do not have MDD. Structural abnormalities are seen in the frontal-limbic and hippocampal areas of the brain. They are there at the beginning of MDD and may even precede it! This is shown by imaging studies on those experiencing their first major depressive episode, before starting treatment. After multiple episodes of depression, the volume of the hippocampus decreases. This decrease correlates with observed memory problems.

So far, research has determined the regions of the brain that are affected by MDD, but we don't know why and there are few, if any effective treatments. Tune in tomorrow to learn about what is available to help combat the cognitive symptoms of MDD. Ultimately, more research needs to be done in this area to give sufferers relief from the frustrating cognitive symptoms.
 
MDD is not just a mood disorder or an attitude that you can change. Have you ever wished you had something to show for your pain...a broken leg, a tumor or something to explain why you are the way you are? There are physical abnormalities to explain my foggy thoughts and crumby short-term memory. Unfortunately we can't all go get brain imaging done to prove it, but knowing that my issues are scientifically validated give me comfort. Even though I've known it for a while, a lot of the world doesn't. I'm not lazy, I have MDD. It's real. Take that stigma!

(P.S. I'm not a doctor or an expert, I'm just sharing what I've read that makes me say Wow!)

Sources:
cogstate.com 
Office of Mental Health 
Trivedi and Greer, 2014