Repetitive transcranial magnetic stimulation (rTMS) may improve working memory in patients with schizophrenia, according to a small study published by Zafiris J. Daskalakis and colleagues in Biological Psychiatry in 2013. Patients with schizophrenia received either 20 Hz rTMS over the left and right prefrontal cortex or a sham treatment, and the rTMS improved working memory on a particular task, the n-back task, wherein patients are asked to recall whether a stimulus they’re currently viewing is the same as the previous one they viewed, or one they viewed several times back. Twenty sessions of rTMS over a period of 4 weeks brought memory back to the levels seen in normal controls.
Editor’s Note: Since many patients with bipolar disorder also have deficits in prefrontal-based memory and performance even when euthymic, it will be important to see if rTMS would also be helpful in these patients. RTMS at 20 Hz increases neuronal activity as measured by PET scan of the prefrontal cortex and other regions of the brain, and this lasts for at least 48 hours after each treatment.
Since many patients with schizophrenia and bipolar disorder show deficits in prefrontal activity at baseline, the normalization of these alterations could relate to the memory improvement. This proposition could be tested relatively easily.
At the 2012 meeting of the American Academy of Child and Adolescent Psychiatry (AACAP), Carrie E. Bearden presented data from a study that predicted conversion to psychosis in at-risk youth (those who have prodromal symptoms or a particular genetic mutation that leads to psychosis) by observing white matter abnormalities.
Bearden found that the degree of white matter abnormality seen during magnetic resonance imaging (MRI) was proportional to the degree of cognitive deficit in patients who subsequently developed a first episode of psychosis. The white matter abnormalities were seen particularly in the superior longitudinal fasciculus (SLF) and were associated with increased severity of symptomatology. The overall degree of white matter alteration was also significantly related to clinical outcome 15 months later.
Editor’s Note: The SLF is a major neuronal conduit between prefrontal cortical systems, which are responsible for cognition and planning, and the parietal cortex, which is responsible for spatial abilities. Disruption of this fiber track has been related to difficulties in social cognition and “theory of mind” concepts, like inferring what others might be thinking.
At a symposium on new research on juvenile bipolar disorder at the meeting of the American Academy of Child and Adolescent Psychiatry (AACAP) in 2010, Ronna Fried from Massachusetts General Hospital reviewed executive function deficits that occur in children with bipolar disorder. These include difficulties in planning, working memory, response inhibition, emotional control, initiative, self-regulation, and the ability to shift focus when required.
Fried and her research group found that comorbid ADHD occurred in 69% of bipolar I children compared with 16% of controls. (ADHD involves many of the same executive function difficulties that occur in bipolar disorder—poor attention and difficulties with learning and memory.) Executive function deficits were observed in 45% of bipolar I patients compared with 17% of controls. Children with bipolar disorder who had executive function deficits had lower IQs, more difficulty reading, lower social functioning, decreased occupational functioning on long-term followup, and overall poor outcome of their illness.
Editor’s Note: These data emphasize the importance of cognitive remediation techniques in those who have major executive function deficits. Dr. Fried emphasized that rehabilitation works, and indicated its use is important for these children in order to moderate the otherwise more severe course of illness they may experience compared with those without executive function deficits.