Mark, a 43 year-old executive, saw his doctor for his annual physical. Reviewing his laboratory tests, the doctor noted that Mark's total cholesterol level was for the first time over 200mg/dL.

As a preventative measure the doctor prescribed a statin, a class of cholesterol-lowering drugs. His cholesterol levels declined, but so did his mood. Mark was now struggling with and .

Over the years I've seen many patients like Mark, being treated by physicians with the mantra of "the lower the better" when it comes to cholesterol levels.

Although cholesterol-lowering medications might lower the risk of heart attacks or strokes our obsession with lowering cholesterol completely ignores the potential psychological consequences that may occur with low cholesterol.

A few years ago an excellent study was published in the Journal of Psychiatric Research with little from the press and essentially no reaction from my colleagues. The simple study followed nearly 4,500 US veterans for 15 years. At the end of the study the researchers found that men with low total cholesterol levels and depression were 7 times more likely to die prematurely from unnatural causes such as and accidents than the other men in the study!

For many years, scientific studies have linked low cholesterol to depression and impulsive behaviors, including suicide and violence.

A 1993 study reported, "Among men aged 70 years and older, categorically defined depression was three times more common in the group with low total plasma cholesterol...than in those with higher concentrations..."

A study of men aged 40 to 70 found that the men with long-term, low total cholesterol levels "have a higher prevalence of depressive symptoms" compared to those with higher cholesterol levels.

Women with low cholesterol levels are also vulnerable to depression. A Swedish study involving 300 healthy women, aged 31 to 65, concluded that women in the lowest cholesterol group-the bottom ten percentile-suffered from significantly more depressive symptoms than the others in the study.

The vast majority of the research leads to the same conclusion; low cholesterol leads to higher rates of depression or depressive symptoms.

For many with depression suicide is a tragic reality. As low cholesterol is linked to depression, low cholesterol is also a risk factor in suicide attempts.

University of Minnesota researchers found that people with total cholesterol levels lower than 160 mg/dL were more likely to commit suicide than those with higher cholesterol levels.

Cholesterol and blood fat levels were found to be lower, on average, among patients with bipolar disorder who had attempted suicide than bipolar patients who had not.

The results of a 2008 study of hospitalized patients suggested that low cholesterol may be associated with suicide attempts.

Suicide is not the only type of violence associated with lower cholesterol levels. Homicide and other acts of violence committed against others have been found to be associated with low cholesterol.

When Swedish researchers compared cholesterol measurements of nearly 80,000 men and women to subsequent arrests for violent , they came to the conclusion that "low cholesterol is associated with increased subsequent criminal violence."

Scientists, however, don't exactly know why low cholesterol is linked to depression, suicide, and violence. Some researchers theorize that low levels of cholesterol alter brain chemistry, suppressing the production and/or availability of serotonin or other neurotransmitters in the brain.

But what is clear and what many overlook is the fact that cholesterol plays a vital role in the human body. Foremost, it is valuable and necessary for optimal brain function as the brain is the most cholesterol-rich organ in the body.

Among its many other roles cholesterol also

ensures that cell walls function properly is converted into vitamin D is used to make and serves as a major part of the coating of nerve cells

Despite cholesterol's vital role in human health and healthy brain function, cholesterol continues to be vilified by the medical profession. With constant ads about the dangers of high cholesterol leading to heart disease, heart attacks and strokes, many millions of Americans every year are prescribed statins to lower their cholesterol.

Is it any wonder then, that the 13 marketed statins generate more prescriptions and more money in sales than any other class of prescription drugs?!

It's important to set aside this hype and to appreciate the critical role that cholesterol plays in both physical and mental health, especially its role in depression.

Low cholesterol is one of the most common factors I see in treatment refractory depression.

In stating that, I evaluate total cholesterol levels of all patients suffering from depression. I find that a total cholesterol level below 150 mg/dL is often a contributing factor to depression. Raising cholesterol levels by dietary interventions or adjusting statin for some patients may be the key to treating their depression.

I am going to end this blog with a list of references that support the link between low cholesterol and mental health. Please be sure to check out the references below.