One of the significant problems people with bipolar disorder grapple with is weight gain. Many online commentators have suggested that this is due largely to the impact of certain types of medications commonly being prescribed for bipolar disorder (a class of medications called atypical antipsychotics).

However, recently published research suggests that the whole picture is a bit more complicated than laying blame on the medications alone.

First, it helps to start off by understanding America’s overall weight problem. Nearly two-thirds of all Americans are overweight (over 70% of all men and over 61% of all women), and one-third of us are considered obese (National Health and Nutrition Examination Survey). America is fat, there’s simply no easy or other way to say it. So if you’re packing a few extra pounds, you’re in the norm for America today.

Susan Simmons-Alling and Sandra Talley (2008) examined the research into the factors surrounding weight gain and bipolar disorder. They note that 35% of people with bipolar disorder are obese, the highest percentage of any psychiatric illness. They also reviewed previous research which suggested factors that may be contributing to this problem: gender, geographical location, co-existing binge-eating disorder (up to 18%), co-existing bulimia nervosa (up to 10%), higher numbers of depressive episodes, treatment with medications that cause weight gain, high carbohydrate consumption, and physical inactivity.

But research results to-date have been decidedly mixed about whether bipolar disorder (and its treatment) causes significant weight gain, or whether weight is more of a general population issue that can be magnified by the presence of bipolar disorder (and its treatment). The researchers note one study that found that 68% of people seeking treatment for bipolar disorder presented as overweight or obese (a statistic that mirrors the general population). But another study found that newly-diagnosed bipolar patients were within normal weight range, finding weight gain only occurred after diagnosis and treatment.

The researchers look at a number of possible contributing factors, including genetic and biological processes and neurotransmitter activity. Research into these areas that specifically examine weight gain in bipolar disorder simple don’t yet exist, but the authors suggested there are “similar patterns if neurochemical dysregulation between the two disorders [bipolar disorder and eating disorders] that might account for weight changes.” They also point to research that suggests that eating disorders and mood disorders may “coaggregate” in families. This begs the question, however, that if that were true, why are we not seeing a huge rise in obesity or weight problems in people taking more typical antidepressants. (While certainly weight gain may be a side effect of some antidepressants, it hasn’t garnered nearly as much attention as the weight gain experienced by people taking the newer atypical antipsychotic medications.)

When the researchers look at psychopharmalogical influences, they get to the kicker — “the pharmacological mechanisms underlying weight gain are poorly understood.” In other words, we don’t know exactly how or why these drugs may be causing weight gain in people. What they do note are possible predictors of weight gain while on the medications — gaining 4 or more pounds in the first 3 weeks of taking the medication, being younger, non-White ethnicity, having lower weight at the outset of treatment, and nonrapid cycling. Sadly, the researchers say very little else to say about the weight gain problems of many atypical antipsychotics. Given what has been published about the Zyprexa research trials in the past 2 years, I’d say this was an unfortunate choice by the authors.

They do note that metabolic syndrome has been shown to be present in up to 30% of people with bipolar disorder (metabolic syndrome is a set of health factors that increase the risk of heart disease and diabetes). What they don’t say anything about is whether this is significantly higher than the general population (it’s about 25% in the general population) and whether bipolar disorder may cause this increased risk.

Additional theories about the increased weight risk associated with bipolar disorder include a childhood history of neglect or abuse, which is reported in 36% to 49% of people with bipolar disorder. Such abuse or neglect is also highly associated with eating concerns, according to the researchers. Alcohol abuse and smoking are also singled out as possible factors, both occurring with increased prevalence within people who have bipolar disorder than those without (and both contributing to additional health concerns, such as metabolic syndrome).

Last, the authors point out that people with bipolar disorder often have lower income levels, fewer years of education and may be in poor social support situation (e.g., lack of a stable relationship). These factors may also contribute to making poorer diet choices and have worse eating habits.

The assessment the authors provided was a basic review of the literature, and as such, couldn’t come to any smoking-gun conclusions. What they found was a pretty complex picture with no obvious answers to the problem of increased weight gain in people with bipolar disorder. They do suggest strategies, however, to try and address the issue head-on, by having the physician carefully monitor the person’s health and weight, and provide dietary education as needed. The lack of a more in-depth look of the issue of the atypical antipsychotics and weight gain was disappointing. But what they did find points to the need for far more refined and focused research into this area.

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Simmons-Alling, S. & Talley, S. (2008). Bipolar Disorder and Weight Gain: A Multifactorial Assessment. J Am Psychiatr Nurses Assoc., 13, 345.

The researchers made no disclosures of any conflicts of interest in the publication of this article.