Adolescent Obesity Connected to Brain Impairment
As childhood obesity has increased over the past several decades, the metabolic syndrome has also become more prevalent among children and adolescents. The metabolic syndrome consists of five measures related to obesity: elevations in fasting glucose levels or insulin resistance, a high proportion of LDL (“bad” cholesterol) to HDL (“good” cholesterol), elevated triglycerides, hypertension, and abdominal obesity or high waist circumference. A patient with three of these abnormalities would be diagnosed with the metabolic syndrome.
In adults, the metabolic syndrome has been associated with neurocognitive impairments. Researchers decided to look at adolescents with the metabolic syndrome to determine whether these brain effects are a result of long-term metabolic impairment or whether they can take place after short-term periods of poor metabolism as well. In a study published by Yau et al. in the journal Pediatrics last year, 49 adolescents with the metabolic syndrome were compared to 62 adolescents without the syndrome who had been matched for similar age, socioeconomic status, school grade, gender, and ethnicity.
The adolescents with the metabolic syndrome had lower scores on tests of math, spelling, attention, and mental flexibility, as well as a trend for lower overall intelligence. In brain measures such as hippocampal volume, amount of brain cerebrospinal fluid, and microstructural integrity in white matter tracts, the seriousness of the metabolic syndrome correlated with the level of abnormality on these measures.
Editor’s Note: It seems as though even short-term problems with metabolism can lead to brain impairments like lower cognitive performance and decreased integrity of brain structures. These effects are even seen before vascular disease and type 2 diabetes are manifest.
It is doubly important, in terms of both cardiovascular and neurobiological risks, to look out for one’s medical and psychiatric health. Reducing the abnormal components of the metabolic syndrome should produce benefits for both the cardiovascular system and the central nervous system.
Almost 40% of patients with bipolar illness in the US have the metabolic syndrome, so considerable effort will be required to improve this public health crisis.
Adolescent Brain Particularly Susceptible to Decline in IQ from Marijuana Use
A decades-long study in New Zealand suggests that people who use marijuana persistently during adolescence lose 8 IQ points by adulthood compared to their peers who never use marijuana. Quitting or reducing cannabis use after adolescence did not restore the intellectual abilities in those who used it persistently in their youth. This is the first study of its kind that controlled for differences in functioning that existed before adolescence.
Participants took part in neuropsychological testing at the age of 13, prior to any cannabis use, and then were periodically interviewed about their use of the drug (at the ages of 18, 21, 26, 32, and 38). At age 38 they underwent IQ testing again.
Although persistent cannabis users tended to have fewer years of education, the lack of education was not responsible for the difference in adult IQ.
Those participants who only began using cannabis persistently in adulthood did not see a decline in IQ, suggesting that the adolescent brain is particularly susceptible to damage from cannabis use.
