Most, including myself, would argue that, particularly without treatment, bipolar disorder is a decrease in functioning. Untreated depression and mania disrupt every part of a life in negative ways – that’s what drives people to get treatment in the first place. But if bipolar disorder is an illness and is a decrease in functioning, why hasn’t evolution naturally selected out bipolar disorder? Why do we still see bipolar disorder today?

As I work, I battle the stigma around mental illness. It feels like often, all day, every day, it's the only thing I do. But I do it because I feel it's important. I feel it matters. I feel it changes people's lives. And one of the misconceptions I've heard multiple times recently is about bipolar and mental illness diagnosis. That by accepting a diagnosis of a mental illness this somehow removes the responsibility from the individual for their own wellness. That, somehow, a mental illness diagnosis makes the patient weak because now they are looking for someone to "save" them or "cure" them. Well nothing could be farther from the truth. Getting a mental illness diagnosis is only the first step in what a patient must do in order to recover.

I've been studying mental illness for a long time and while I knew the answer to this question, I couldn't really have told you why. This is mostly because I haven't done a lot of work on personality disorders, but I have had occasion to learn more about them recently. No, bipolar disorder is not a personality disorder, and here's why.

There's nothing new under the sun. Or so I've been told. And while nothing new may exist, we sure learn about new things all the time. People do lament that our understanding of bipolar disorder and other mental illnesses is too lacking, but each year we learn more about the human brain and mental illness. Here then are top ten things we learned this year about mental illness.

By now we know the symptoms of bipolar disorder - wild mood swings from euphoria (mania or hypomania) to depression. We know that bipolar disorder comes in lots of variants, bipolar 1, bipolar 2, cyclothmia, rapid-cycling and so forth. But when are the symptoms of bipolar disorder not bipolar disorder? Are there other illnesses that can account for bipolar symptoms? When is bipolar disorder not bipolar disorder?

We all have gut reactions to information. It's the reaction when our stomach knots or tumbles, our breathing quickens or stops, our eyes light up or look down. It's the reaction we have before realizing we're having a reaction. And gut reactions around mental illness can be powerful. The problem is, our gut reactions are so often wrong about mental illness and mental illness treatment.

I’ve written about this several times, but never said it quite this directly: No one is a diagnosis. No one fits the criteria for “bipolar” or “depression” exactly. No one is a “Patient Like You.” It’s why someone only has to have five out of eight characteristics to be diagnosed with depression. Because there is recognition within the medical community that “depression” isn’t a single thing, much as “bipolar” isn’t a single thing. Those words represent diagnoses that exist along a spectrum. In writings elsewhere I have suggested what I call a “dimensional” diagnosis. (And this is probably because I’m a computer science-y kind of gal.) Basically you have symptoms and diagnoses that exist along multiple axes. Then, depending on where the dots cluster, you essentially have a Venn diagram of diagnoses. It’s OK if you didn’t quite follow that. I know. It’s complicated. But humans are complicated creatures. I like chocolate ice cream, you like vanilla. Humans are a heterogeneous bunch. Why then, if we understand this, do we have names in the first place? Is the term “bipolar” really even useful? In short, yes, it is. And yes, we need those labels, even if they are ill-fitting.

In response to some of the comments I see here and elsewhere, here is my response to another ten myths about bipolar disorder.

Common messages spread by certain special interest groups are that “mental illness doesn’t exist” and “there is no biological evidence for mental illness.” It’s not surprising I take great exception with these claims. So do most doctors. But the brain is an extremely complex organ and refuting the above notions is hard. It’s not a two-word response. So, I’m going to attempt to give a two-part overview, in plain English, of some of the research around the biology of major depressive disorder according to a meta-analysis done in 2010 (see below).

When I discovered I was bipolar, I suddenly became scared of everything. Things that never crossed my mind started to shudder through my bones and produce endless waterfalls of tears. I was afraid of diagnosis. I was afraid of what it meant. I was afraid of psychiatrists. I was afraid of treatment. I was afraid of not getting treatment. I was afraid of what the treatment would do to me. Mental illness means being afraid.