Low levels of vitamin D levels are common, particularly in older adults and in African Americans and Hispanics. Unfortunately, low vitamin D is associated with decline in two types of cognitive functioning: episodic memory (memories of autobiographical events) and executive function (reasoning, problem-solving, planning, etc.).
A recent study with a particularly diverse group of participants, over half of whom were African American or Hispanic, found that over a period of about 5 years, episodic memory and executive function declined faster in older adults with low levels of vitamin D.
Average vitamin D levels for the entire group of 382 adults were below national standards. Levels of 25-hydroxy vitamin D should be between 20 and 50 nanograms per milliliter of blood. The average fell just below this, at 19.2 ng/mL. Over a quarter of participants had vitamin D deficiency, with levels below 12 ng/mL, and another 35.1% had vitamin D insufficiency, with levels between 12 and 20 ng/mL.
African Americans and Hispanics had lower levels of vitamin D (17.9 ng/mL and 17.2 ng/mL, respectively) than whites (21.7 ng/mL). Average vitamin D levels were lower in participants with dementia compared with those who had mild cognitive impairment or normal cognitive function.
Vitamin D levels can depend on factors such as dairy intake, sun exposure, and exercise. It has not been determined whether taking vitamin D supplements could slow down cognitive decline, but vitamin D supplementation has several benefits. Compared to placebo, supplementation with vitamin D increases response to antidepressants. A high percentage of children with major psychiatric disorders are vitamin D deficient, and it is also estimated that about 40% of adults in the US have a vitamin D deficiency.
The study by researcher Joshua W. Miller and colleagues was published in the journal JAMA Neurology in September.
Many patients with bipolar disorder experience cognitive deficits that impede their recovery and that persist during times of wellness. In a double-blind placebo-controlled study by K. N. Roy Chengappa et al. published in the Journal of Clinical Psychiatry in 2013, the herb Withania somnifera (WSE, commonly called ashwagandha and sold under the name Sensoril) was significantly better than placebo at improving patients’ performance on three different cognitive tasks.
In the eight-week study, 53 patients took either 500 mg of WSE or placebo in addition to their regular medications.
The herb, which has traditionally been used in Ayurvedic medicine in India as an aid to resisting stress and disease, improved performance on digit span backwards (a test of short-term memory in which the subject must repeat a sequence of numbers backwards), Flanker neutral (a test of response time in which a subject must repress their instinct to give an incorrect response), and the Penn Emotional Acuity Test (which requires subjects to correctly identify facial emotions depicted in photographs).
Mood and anxiety levels were not different for the group taking WSE and the group taking placebo.
The researchers hope to continue their investigation of WSE with larger and longer-term studies that will explore the effects of different doses of WSE.
Severe malnutrition in the first year of life even when corrected for the rest of a person’s life leaves a legacy of permanent cognitive deficits, marked deficits in attention, and increases in depression, conduct disorders, and medical disorders compared to carefully matched controls. Jamina Galler, a researcher at Harvard Medical School, gave a plenary talk at the 2013 meeting of the American Academy of Child and Adolescent Psychiatry on the long-term effects of even short-term childhood malnutrition, including marasmus (calorie deficiency) and kwashiorkor (protein deficiency).
Galler’s studies followed three generations of people born in Barbados and observed the consequences of prior malnutrition, which was completely eliminated in Barbados by 1980. The consequences of malnutrition in the first year of life not only affected the first (G1) generation, but subsequently their offspring in the G2 generation who also suffered an excess of attention-deficit hyperactivity disorder, low IQ, and low annual income into adulthood. That is, the early malnutrition had transgenerational effects.
Malnutrition is a huge problem worldwide and is especially bad in sub-Saharan Africa and some parts of Asia. Globally, malnutrition accounts for 50% of the deaths of children under age five. However, even in the US hunger is a problem for one in four children, or about 16 million individuals, and the long-term consequences of hunger remain to be further studied.
Studies in animals indicate that early malnutrition has epigenetic effects that can be passed on to four future generations before they are reversed. Epigenetic effects refer to environmental factors that cannot change the sequence of DNA, but change how easily it is transcribed by adding or taking away acetyl and methyl groups on DNA and histones, the structures around which DNA is wound. Malnutrition (defined as 6–8% casein, a type of protein, in the diet instead of the normal 25%) in rodents affects cognitive abilities and blood pressure and can lead to diabetes, obesity, and other metabolic abnormalities. The next generation is also affected because a previously malnourished mother huddles too much with her offspring, and they become obese as a result of these poor parenting skills. The second generation also exhibits epigenetic changes in the prefrontal cortex (such as too few glucocorticoid receptors due to methylation of the glucocorticoid promoter) and fewer neurons in the hippocampus.
Editor’s Note: Other data indicate similar long-lasting epigenetic and transgenerational effects of other types of childhood adversity, such as verbal, physical, or sexual abuse. These findings in humans are also paralleled by findings in animals, and give strong credence to the idea that the environment can have long-lasting effects on neurobiology and behavior via epigenetic effects that can be superimposed on whatever genetic effects are inherited.
Data from this editor (Robert Post) and colleagues on verbal abuse in childhood is striking; this supposedly less severe form of abuse is still associated with a more difficult course of bipolar disorder and an increase in medical comorbidities. Thus, the experience of early abuse, even just verbal abuse, appears to have long-lasting consequences for psychiatric and medical health into adulthood.
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.