Blood sugar and the brain in learning and behavioral disorders

The brain needs a steady supply of glucose to work normally. Disorders of blood sugar regulation, whether hypoglycemia or insulin resistance (precursor to type 2 diabetes), deprives the brains cells of the fuel to produce the energy they need to function. Research just published in the journal Diabetologia examines the cognitive impairments present in adolescents when insulin resistance and overweight have progressed to type 2 diabetes.

"Central nervous system abnormalities, including cognitive and brain impairments, have been documented in adults with type 2 diabetes...Assessing adolescents with type 2 diabetes will allow the evaluation of whether diabetes per se may adversely affect brain function and structure years before clinically significant vascular disease develops."

The authors compared two groups of overweight adolescents, one with and the other without type 2 diabetes. The depredations of insulin resistance on the brain were stunning:

"Adolescents with type 2 diabetes performed consistently worse in all cognitive domains assessed, with the difference reaching statistical significance for estimated intellectual functioning, verbal memory and psychomotor efficiency...[and] executive function, reading and spelling. MRI-based automated brain structural analyses revealed both reduced white matter volume and enlarged cerebrospinal fluid space in the whole brain and the frontal lobe in particular... In addition, assessments using diffusion tensor imaging revealed reduced white and grey matter microstructural integrity."

The authors conclusion places both clinicians and parents on the alert:

"These abnormalities are not likely to result from education or socioeconomic bias and may result from a combination of subtle vascular changes, glucose and lipid metabolism abnormalities and subtle differences in adiposity in the absence of clinically significant vascular disease."

On the hypoglycemic pole of glucose regulation we can appreciate earlier fascinating research published Pediatric Research documenting an impaired neurotransmitter response to falling blood sugar in children with ADD (the catecholamines epinephrine and norepinephrine attenuate the drop in blood sugar).

"Eating simple sugars has been suggested as having adverse behavioral and cognitive effects in children with attention deficit disorder (ADD)...metabolic, hormonal, and cognitive responses to a standard oral glucose load (1.75 g/kg) were compared in 17 children with ADD and 11 control children."

Their data showed a significant difference between ADD and control children:

"The late glucose fall stimulated a rise in plasma epinephrine that was nearly 50% lower in ADD than in control children. Plasma norepinephrine levels were also lower in ADD than in control children..."

The authors' conclusion indicates the need for conscientious blood sugar management through dietary and other measures:

"These data suggest that children with ADD have a general impairment of sympathetic activation involving adrenomedullary as well as well as central catecholamine regulation [of blood sugar]."

Similar phenomena are presented in a paper published in the Journal of the American Academy of Child & Adolescent Psychiatry describing abnormalities of brain metabolism in girls with ADHD:

"This study assesses the effect of attention-deficit hyperactivity disorder (ADHD) and gender on cerebral glucose metabolism (CMRglu), using positron emission tomography and 18F-fluorodeoxyglucose."

An interesting gender difference emerged from the data:

"However, the global CMRglu in ADHD girls was 15.0% lower than in normal girls, while global CMRglu in ADHD boys was not different than in normal boys. Furthermore, global CMRglu in ADHD girls was 19.6% lower than in ADHD boys and was not different between normal girls and normal boys."

Gender differences that must be respected are pronounced here and throughout medicine and biology:

"The greater brain metabolism abnormalities in females than males strongly stress that more attention be given to the study of girls with ADHD."

Addressing the dysfunctions in blood sugar dysregulation associated with disorders of learning and behavior requires understanding that deleterious eating conducts can manifest as a form of self-medication. A paper recently published in Current Psychiatry Reports brings attention to this:

"In the past decade, we have become increasingly aware of strong associations between overweight/obesity and symptoms of attention-deficit/hyperactivity disorder (ADHD) in children, adolescents, and adults."

The need to satisfy imperious physiological urges on a cellular level when an individuals genetic needs are not being met can overwhelm all advice and intention to acquire more wholesome and sustainable habits:

"It is also proposed—based on the compelling evidence that foods high in fat, sugar, and salt are as addictive as some drugs of abuse—that excessive food consumption could be a form of self-medication. This view conforms with the well-established evidence that drug use and abuse are substantially higher among those with ADHD than among the general population."

True remediation demands a functional medicine approach to resolve the underlying cellular and metabolic needs that are not being met so they can be supported in a physiological and sustainable manner to restore normal function.A paper published in the Journal of Nutrition, Health & Aging brings us back to the fundamental importance of glucose regulation for the brain.

"The regulation of glycaemia (thanks to the ingestion of food with a low glycaemic index ensuring a low insulin level) improves the quality and duration of intellectual performance, if only because at rest the brain consumes more than 50% of dietary carbohydrates, approximately 80% of which are used only for energy purpose. In infants, adults and aged, as well as in diabetes, poorer glycaemic control is associated with lower performances, for instance on tests of memory. At all ages, and more specifically in aged people, some cognitive functions appear sensitive to short term variations in glucose availability."