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.

Note: This information is from research and should not be the basis for changing your medication. Everyone is different and people respond to different treatment plans.

1. Statistics on Prevalence of Bipolar Disorder

Bipolar disorder is thought to affect between 1% - 1.6% of people in their lifetime. Or is it? It really depends on your criteria and where you do the studies. New data put international lifetime bipolar numbers at:

• 0.6% for bipolar I
• 0.4% for bipolar II
• 1.4% for subthreshold bipolar (some bipolar symptoms but doesn't rise to the level of the disorder)

You'll note this is a lot less than in the US where lifetime prevalence was found to be 4.4%.

Of particular interest is that 75% of people with bipolar disorder had additional disorders, predominantly anxiety disorders.

And perhaps most upsetting is that while 1-in-4 people with bipolar disorder reported a suicide attempt, the majority of people did not have regular contact with mental health professionals underscoring the need for both illness diagnosis and treatment.

2. How often is Bipolar Diagnosis Mistaken for Depression?

Depression is a major feature of bipolar and particularly in the case of bipolar type II, depression may be so prevalent that the bipolar component of the illness is missed altogether and the person is incorrectly diagnosed as having unipolar (non-bipolar) depression. This is a big problem as those with depression tend to be treated with antidepressants and this can worsen bipolar symptoms both in the long and short term.

Some people feel this is due to the stringent diagnostic criteria used to diagnose bipolar disorder and feel the current criteria miss too many cases of bipolar disorder.

To test this, a group screened 5635 people with major depressive disorder for bipolar depression and amazingly, 16% were found to have bipolar using the current diagnostic criteria. Even more amazingly, 47% met a proposed looser set of bipolar diagnostic criteria.

The more we understand about depression and bipolar disorder the more it seems that bipolar and depression exist on a spectrum and are not really "polar" at all.

3. Predictor of Bipolar Treatment Success

One of the major (if not the biggest) predictors of treatment success is the number of bipolar episodes experienced before treatment. In short, the fewer number of episodes you have had, the better your chance of successful treatment. This is why I'm always harping on getting help as early as possible -it improves your chance of success.

In one study, patients experiencing their first episode of mania had twice the chance of successfully responding to olanzapine (Zyprexa) than those who had experienced 1-5 episodes of mania.

The chance of relapse into depression or mania was reduced by 40% - 60% for those who had 1-10 episodes compared to those who had more than 10. Looking at the numbers, it appears this relationship holds truer for mania than for depression.

4. Antimanic Treatment Efficacy - Drugs Compared

There is little known about how drugs compare to each other when treating illness because study is put into ensuring a drug works before coming onto the market, not on how it stacks up to existing drugs (there's no monetary incentive for that type of study).

However, this year two studies were conducted that attempted to compare various antipsychotics, anticonvulsants (antiepileptics) and mood stabilizers in treating mania.

The first study ranked the drugs in the following order in terms of effectiveness:

• Tamoxifen (Soltamox, Nolvadex)
• Haloperidol (Haldol)
• Carbamazepine, valproate and second-generation antipsychotics

The second study attempted to rate medications on antimanic efficacy and tolerability and ranked the drugs in this order:

• Haloperidol, risperidone (Risperdal), and olanzapine
• Lithium, quetiapine (Seroquel), aripiprazole (Abilify), and carbamazepine (Tegretol)
• Lamotrigine (Lamictal), topiramate (Topamax) and gabapentin (Neurontin) (no better than placebos)

Please look at the full study information before even considering basing a decision on this data - there are many limitations.

5. Are Two Antidepressants Better Than One?

It is common in clinical practice to add a medication to an existing antidepressant treatment and often this second medication is an antidepressant. However, research does not support the use of this practice and a further study came out this year with similar negative results.

Patients were given an antidepressant plus another antidepressant or a placebo and their progress was tracked. In 12 weeks and again at 7 months, those with two antidepressants did not do better than those with an antidepressant plus a placebo. In fact, in one case they were doing worse due to the increased incidence of side effects.

The rest of the top ten things we learned about mental illness will be discussed next week.

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