Review: Reconsideration of bipolar disorder as a developmental disorder
Reconsideration of bipolar disorder as a developmental disorder: Importance of the time of onset
Pierre Alexis Geoffroy et al, J Physiology Paris, 2013
Eight admixture studies have demonstrated three homogeneous subgroups of patients with bipolar disorder, identi?ed by their age at onset (early, intermediate and late age at onset), with two cutoff points, at 21 and 34 years.
The early onset group had more: Suicide attempts, rapid cycling, drug and alcohol abuse, psychotic symptoms, panic disorder, OCD, and a positive family history for affective disorder. Early onset illness should be recognized and treated earlier.
In Animals, Exposure to High Fat Diet During Pregnancy Can Affect Offspring’s Neurological Development
New research in non-human primates suggests that exposure to a high fat diet during pregnancy and in early development prior to weaning can increase the offspring’s propensity for anxiety later in life.
The new research echoes 2010 findings about rats. Researcher Staci D. Bilbo and colleagues reported in the journal of the Federation of American Societies for Experimental Biology that in rats, a high fat diet during pregnancy and lactation led to offspring with greater body weight, increased inflammation, and problems with anxiety and spatial learning. Switching to a standard diet after weaning did not eliminate these outcomes.
The recent research by Jacqueline R. Thompson and colleagues, published in the journal Frontiers in Endocrinology in July 2017, suggests that maternal nutrition in the primate during pregnancy and lactation can have long-lasting effects on offspring’s neurological development, altering the brain and endocrine system. These changes occurred even if the offspring began a normal diet after weaning.
65 female Japanese macaques were divided into two groups, one that received a high-fat diet and one that received a normal diet. In the offspring of mothers who ate a high-fat diet, the researchers found impaired development of neurons containing serotonin. The offspring of the high-fat diet group also showed behavioral alterations such as increased anxiety.
The high rates of obesity in the US and other developed nations make these findings particularly important. The researchers suggest that 64% of women in the US who are of reproductive age are overweight, and 35% are obese. Co-author Elinor Sullivan suggested that the findings from the study could motivate mothers to make healthy nutritional decisions, not only for themselves but for their children as well.
Adolescence is a Sensitive Period for Fear Learning
Adolescence can be a time of vulnerability to illness. Anxiety disorders increase during this period, and three-quarters of adults with anxiety disorders trace the illness back to their childhood or adolescence. The most common treatments for anxiety disorder are based on the idea of fear extinction. A certain stimulus, like a social situation or seeing a spider, provokes a fear reaction in the brain. Through gradually increasing exposure to the stimulus and extinction training, the person becomes desensitized to the stimulus. New research on rodents presented by Francis S. Lee at the 2015 meeting of the Society for Biological Psychiatry suggests that the extinction process is diminished during adolescence.
At specific stages of maturation, neural circuits related to particular abilities can become flexible. Brain and behavior become sensitive to and are increasingly shaped by experience. Studies of rodents and humans have shown that adolescence is a time when the neural circuitry for fear extinction is in flux. In mice, this period falls around their 29th day of life. Lee reported that around this time, the mice begin to exhibit resistance to extinction of fear learning.
In adolescent rodents, there is a surge of contextual fear learning and retrieval that is mediated by hyper-connectivity of the ventral hippocampus and the amygdala to the prelimbic part of the prefrontal cortex. In contrast, the pathway from the amygdala to the infralimbic cortex mediates the extinction of this type of learning. Because the prelimbic pathway for fear learning is overactive, the infralimbic pathway for extinction learning is less effective.
Adolescent mice temporarily lose their ability to retrieve memories related to cue-dependent (as opposed to context-dependent) fear learning. Remarkably, when these animals proceed into adulthood, the fear learning associated with cues returns and becomes accessible again.
This could help explain how teenagers can lose fear conditioning to cues (for example, speeding through a red light) they learned in childhood. The fear is forgotten (or becomes inaccessible) in adolescence, but then what had been learned is again “remembered” (retrieved) in adulthood. Read more
