Diabetes Tied to Poor Impulse Control

Patients with newly diagnosed Type 2 diabetes were significantly more likely to show poor impulse control in psychological testing than healthy people....

In the standard Go/NoGo test of impulse control, newly diagnosed diabetics made about 50% more errors of commission than normal controls, regardless of whether they were overweight.

The differences were not attributable to cognitive impairment, the researchers concluded, because diabetic patients performed as well as controls on the Wisconsin Card Sorting Test of executive function.

"Our results showed that middle-aged, newly diagnosed, and medication-free patients with Type 2 diabetes have a particular neuropsychological deficit in inhibitory control of impulsive response, which is an independent effect of diabetes apart from being overweight," Yasuhiko Iwamoto, MD, of Tokyo Women's Medical University in Japan, and colleagues wrote.

They suggested the findings could help explain why diabetic patients find it difficult to make the recommended lifestyle adjustments such as avoiding high-fat foods and maintaining daily exercise.

The researchers explained that decision-making about daily activities relies on brain functions in different cerebral regions, mixing predictions of future rewards and punishments, inhibition of impulsive responses, and executive functions.

Overeating, they explained, occurs when the prospect of immediate reward overwhelms inhibitions that derive from awareness of negative consequences. "In such conditions, rapid reward prediction or impulsive response to environmental stimuli prevails over the preparations by executive function," Iwamoto and colleagues asserted.

Earlier studies had indicated that reward predictions by overweight individuals tend to be higher than those of normal weight people, and their impulse control was generally lower. Consequently, the Japanese researchers sought to test diabetic patients for performance on psychological tests that measure these functions.

The Go/NoGo test for impulse control involved showing participants one of two letters, N or H, with instructions to press a button when they saw the N but not H. Pressing the button in response to H was an error of commission, and failing to press it when shown the N was an error of omission. The test also measured reaction times, including slowed responses that sometimes followed errors.

Prediction of future rewards was evaluated with so-called reversal and extinction tasks.

In the former, participants won points for correctly switching images on a computer screen that randomly replaced each other. The extinction task was structured the same way, except that participants stopped winning points for executing the reversal after nine correct responses; at that point, they received points for not responding to the stimulus.

As on a TV game show, correct responses were signaled with a pleasant chime sound, whereas errors were announced with a buzzer. Participants were also assessed for clinical depression and for standard laboratory measures of glycemia and insulin resistance. A total of 27 newly diagnosed Type 2 diabetic patients and 27 non-diabetic controls participated. All participants in both groups were men, and none of the diabetic patients were taking medications for diabetes. The diabetic group included 16 who were overweight (mean BMI 29.8). There were 11 overweight controls (mean BMI 27.6).

Response inhibition in the Go/NoGo test was significantly decreased in the diabetic patients, the researchers reported. In a combined measure of commission and omission errors, labeled d', diabetic patients had a mean value of 2.55 compared with 3.22 for controls (P=0.001).

The difference was most pronounced for errors of commission, with a mean of 10 for patients versus about 6 for controls (P=0.002).

The researchers found a significant interaction between Go/NoGo performance and glycated hemoglobin levels, with an r2 value of 0.287 for d' versus HbA1c (P=0.024). Scores did not differ significantly by weight, although there was a trend toward reduced impulse control in overweight participants. Diabetes did not affect reaction times, overall or after errors, but weight did affect them, with faster reaction times in overweight participants.

Iwamoto and colleagues also found that diabetes status did not affect scores on the reversal and extinction tests. Overweight participants made about 40% more errors on the extinction test compared with normal-weight individuals (P=0.029) but not on the reversal test.

Achievement scores on the Wisconsin Card Sorting Test were similar in all patient groups stratified by weight and diabetes status.

So-called perseverative errors (involving continuous repetition of a response) appeared more common in normal-weight diabetic participants, but rates of these errors varied widely among individuals and the group difference was not statistically significant.

"Our study included only newly diagnosed patients with Type 2 diabetes, suggesting the possibility that the neuropsychological deficits in response inhibition may contribute to the behavioral problems leading to chronic lifestyle-related diseases, such as Type 2 diabetes," they wrote.

However, they acknowledged that the causal arrow could point in the other direction -- that "metabolic changes with diabetes affect brain functions and cause neuropsychological deficits."

Indeed, the researchers observed, some earlier studies have found that metabolic improvements in diabetic patients lead to improved cognitive performance.

"Further longitudinal studies will be useful to detect progression or improvement of neuropsychological deficits associated with metabolic change," Iwamoto and colleagues wrote.

They also recommended more studies into the potential causal role of impulsivity in development of Type 2 diabetes. If confirmed, psychobehavioral interventions aimed at improving impulse control could be beneficial in preventing or treating the disease

Out-of-Control Sugar Cravings

Q: I am a type 2 diabetic. I do well with meals, but I crave something sweet (like cookies, cake, candy) constantly, and most times I lose the battle to resist. How can I get rid of this craving once and for all?

— Jacqueline, Kansas

A: Despite popular beliefs about how blood sugar levels relate to craving, there is very little if any evidence indicating this to be true. Food cravings are largely a psychological phenomenon that relates to old habits and learning. The most likely reason that we see cravings in folks like you who have developed type 2 diabetes may simply be that the history of eating patterns that contributed to the development of the diabetes is persisting. Here's the good news: As is the case with all learned behavior, cravings can be "unlearned."

Cravings can arise in several ways. If you have used food to reward yourself, make yourself feel better when stressed or upset, or celebrate certain special events, depending on how frequently you do this, those foods can become associated with any of the above examples. When you feel these emotions, or are in the situations associated with that food, that association triggers thoughts about the food — in other words, a craving. The problem is that over a lifetime, the number of subtle triggers that become solidly paired with these foods grows. So it’s sometimes impossible to put your finger on the cause of the craving, which leads people to assume it’s being triggered by some internal physiological need (which is probably not the case).

The good news is that there is a simple answer: Stop pairing consumption of the craved food with the craving. Of course, even simple answers are not always easy. Fighting cravings can be tough. They are powerful and very real. So here are a few tips to get you started:

Delay. Wait 10 to 20 minutes (or as long as you can) before giving into the craving. In the best-case scenario, often the craving will subside in that time period, and you will not eat the food at all. However, even at those times when you aren’t able to fully fight off the craving, the time delay helps reduce its power.

Distract. Just thinking about the craved food during the delay can maintain the power of the craving. By distracting yourself and trying not to think about the craved food, you will ensure that the craving weakens.

Avoid. Finding alternatives to your most difficult-to-control foods that are equally satisfying and consuming these in moderation in a planned way (not in response to a craving) allows you to not feel deprived while controlling consumption of the food. Alternatively, some people seem to do well consuming a small amount of the actual craved food at planned times, but recent evidence suggests that this may in fact prolong the removal of the cravings.

Remember, you can take control of cravings.