The couch potato lifestyle common in the US may have consequences later, in the form of deficits in memory, executive functioning (including planning and execution) and processing speed.
At the 2015 Alzheimer’s Association International Conference, researcher Kristine Yaffe and colleagues reported that low levels of physical activity and high rates of television viewing in young adulthood may reduce cognitive capabilities in midlife.
The Centers for Disease Control report that less than 50% of adults aged 18–64 get the recommended minimum of physical activity each week. The guidelines recommend at least 150 minutes of moderate intensity aerobic activity (such as walking briskly) and two or more days of muscle-strengthening activities that work all major muscle groups.
Yaffe says that physical activity can protect against cognitive decline or dementia later on.
Participants in the long-term study who reported burning fewer than 300 calories per 50-minute session three times per week during two-thirds of their followup visits had worse cognition at year 25 than those participants who were more active. Those who watched more than four hours of television per day also had reduced cognition in midlife.
Yaffe stresses that exercising regularly is not just important in keeping weight down and protecting the heart, but also in protecting the brain. Regular physical activity may even prevent illnesses such as Alzheimer’s disease.
People with disorders on the schizophrenia spectrum often suffer cognition problems that affect skills such as the processing of information about people and social situations (social cognition) and the execution of plans (executive function). At the 2015 meeting of the Society for Biological Psychiatry, researcher Larry J. Siever reported that the drug guanfacine improved these types of thinking in people with disorders on the schizophrenic spectrum compared to placebo. Participants were enrolled in a 7.5-week training program to improve cognition.
Exercise isn’t just good for the body—new research suggests it can improve cognition and normalize brain activity.
At the 2015 meeting of the American Academy of Child and Adolescent Psychiatry, researcher Benjamin I. Goldstein reported that 20 minutes of vigorous exercise on a bike improved cognition and decreased hyperactivity in the medial prefrontal cortex in adolescents with and without bipolar disorder.
At the same meeting, researcher Danella M. Hafeman reported that offspring of parents with bipolar disorder who exercised more had lower levels of anxiety.
A plenary address by James J. Hudziak also suggested that exercise, practicing music, and mindfulness training all lead to improvements in brain function and should be an integral part of treatment for children at high risk for bipolar disorder and could be beneficial for all children.
Editor’s Note: Recognizing and responding to mood symptoms is key to the prevention and treatment of bipolar disorder in children and adolescents at high risk for the illness. For these young people, exercise, a nutritious diet, good sleep habits, and family psychoeducation about bipolar disorder symptoms may be a good place to start. Joining our Child Network may also be helpful.
Many people with bipolar disorder suffer cognitive difficulties, and these may progress as a function of the number of mood episodes they experience. At the 2015 meeting of the International Society for Bipolar Disorders, researcher Eduard Vieta described the importance of directly prescribing diet, exercise, good sleep hygiene, smoking avoidance, and cognitive exercises designed to maintain cognitive reserves in people with bipolar disorder. Vieta stressed that one of the most important approaches to maintaining cognition is to help patients achieve and maintain remission. He also noted that those patients with lithium levels of .6meq/l or greater did not see cognitive deterioration.
Some treatments for bipolar disorder can contribute to cognition problems. Topiramate and benzodiazepines can impair cognition, as can atypical antipsychotic drugs and certain antidepressants that block the neurotransmitter acetylcholine. Avoiding these treatments and those with sedative side effects may also be helpful.
Vieta listed a series of drugs with some promise for improving cognition. (These did not include treatments for dementia, which include memantine and a group of drugs that increase acetylcholine by inhibiting its breakdown.)
This editor (Robert M. Post) has taken the liberty of giving a letter grade (A to D) to each drug on Vieta’s list on the basis of the strength of the data supporting its efficacy, its safety and tolerability, and its overall usefulness for patients with bipolar disorder. These recommendations, like other material in the BNN, are subjective and likely to change as more systematic studies on these treatments are published.
A 5mg dose of the antidepressant vortioxetine (Brintellix) was previously reported to have positive cognitive effects in elderly depressed patients. In a 2014 article in the International Journal of Neuropsychopharmacology, researcher Roger S. McIntyre et al. presented data from FOCUS, a study of cognition in depressed patients. The eight-week double-blind study included 18- to 65-year-olds (who were not selected for having cognitive problems per se).
McIntyre and colleagues used two tests of cognition, the Digit Symbol Substitution Test (DSST), which measures attention, psychomotor speed, and executive function, and the Rey Auditory Verbal Learning Test (RAVLT), which measures memory and acute and delayed recall. The researchers found that both the 195 patients taking 10mg/day of vortioxetine and the 207 patients taking 20mg/day of vortioxetine had better performance on both tests than the 196 patients who received placebo.
Response rates (meaning a patient achieved a 50% improvement on a scale of depression) were 47.7% on 10mg of vortioxetine, and 58.8% on 20mg of vortioxetine, compared to 29.4% on placebo. Remission rates were 29.5% on 10mg of vortioxetine and 38.2% on 20mg of vortioxetine versus 17% on placebo. McIntyre suggested that the drug worked both directly and indirectly, improving depression in some, but also improving cognition even in those whose depression did not improve.
The mechanism that could account for vortioxetine’s cognitive effects has not yet been identified. Like other selective serotonin reuptake inhibitor (SSRI) antidepressants, vortioxetine is a potent blocker of serotonin (5HT) reuptake, which it does by inhibiting the serotonin transporter (5HT-T). Unlike other SSRIs, vortioxetine is also a blocker of 5HT3 and 5HT7 receptors, an agonist at 5HT1A and 5HT1B and a partial agonist at 5HT1D receptors. It could be considered a polymodal 5HT active drug in contrast to the more selectively active 5HT-T–inhibiting SSRIs.
Transcranial direct current stimulation (tDCS) shows promise for a range of problems. In new research presented at the 2014 meeting of the Society of Biological Psychiatry, it was reported to be effective for improving cognition in bipolar disorder, alleviating depression, and reducing hallucinations.
How TDCS Works
At the meeting, researcher Marom Bikson discussed tDCS technology. The treatment can be delivered with a 12-volt battery. The anode directs current inward and is excitatory, while the cathode directs current outward and is inhibitory. The dendrites at the top of neurons under the anode are hyperpolarized by the tDCS, leading to relative depolarization of the cell soma, thus increasing excitation. TDCS, unlike repetitive transcranial magnetic stimulation (rTMS), which causes cells to fire, is only neuromodulatory, inducing minor changes in membrane polarization.
TDCS Improved Cognition in Bipolar Disorder
At the 2014 meeting of the American Psychiatric Association, Roberto Delle Chiaie et al. reported that two mA tDCS for 20 minutes for 15 days (anode over the left prefrontal cortex and cathode over the right cerebellum) improved immediate and delayed recall, trail making with a pointer, and motor coordination in 17 euthymic bipolar patients. This very promising result deserves further study and replication.
Antidepressant Effects of TDCS
At the 2014 meeting of the Society of Biological Psychiatry, Collen Loo reported that tDCS had positive effects in depressed patients compared to sham treatment. This complements a 2013 article by Brunoni et al. in JAMA Psychiatry that tDCS plus the selective serotonin reuptake inhibitor (SSRI) antidepressant sertraline (Zoloft) was more effective than either treatment alone.
TDCS for Treatment-Resistant Hallucinations
Jerome Brunelin et al. reported at the meeting that tDCS had positive effects in patients with schizophrenia who had hallucinations that resisted treatment. The positive electrode (anode) was placed over the left prefrontal cortex and the negative electrode (cathode) over the left temperoparietal area, where hallucinations are thought to originate. Stimulation was at two mA for 20 minutes, five days per week for two weeks. Effects lasted as long as 30 days and were associated with reduced functional connectivity of these brain regions.
Low frequency (1Hz) rTMS, which decreases neural activity, also improves refractory hallucinations when applied over the temperoparietal area, which is important for language. Placing the cathode over this area in tDCS is also inhibitory, so comparisons of rTMS with tDCS for suppressing hallucinations would be of great interest and importance.
Vortioxetine (Brintellix) is a new antidepressant that has a range of effects on serotonin receptors, making it different from selective serotonin reuptake inhibitors (SSRIs), the most common type of antidepressants, which work only on the serotonin transporter. Researcher Johan Areberg et al. reported at the 2014 meeting of the American Psychiatric Association that the drug is an antagonist at receptors 5-HT3, 5-HT7, and 5-HT1D; a partial agonist at 5-HT1B; a full agonist at 5-HT1A; and an inhibitor of the 5-HT transporter. The researchers suggested that at doses of 5mg/day, vortioxetine occupies the 5-HT3 receptors and 50% of the serotonin transporter. As dosage increases to 20mg/day, vortioxetine is believed to occupy all of the serotonin targets at clinically relevant levels. Doses of 20mg/day were found to be effective in nine studies. Researcher Gennady Smagin et al. also reported that vortioxetine activates central histamine receptors.
Vortioxetine appears to be useful in patients who have previously failed to respond to antidepressants. Researcher George I. Papakostas et al. reported that in a cohort of about 500 patients who responded inadequately to previous prescriptions of selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs), the 252 taking vortioxetine improved more than the 241 taking the antidepressant agomelatine.
Editor’s Note: Vortioxetine’s superior effects are impressive, as agomelatine, which is approved for use in at least 41 countries including the UK, Canada, and Australia, but is not available in the US, has previously been shown to be more effective than a number of SSRIs in head-to-head comparisons. Agomelatine improves sleep and circadian rhythms via its dual effects as an agonist at melatonin M1 and M2 receptors and an inhibitor of 5HT2C receptors, which results in the release of norepinephrine and dopamine in the frontal cortex.
Vortioxetine may be unique among antidepressants in that it appears to improve cognition. Researcher John E. Harrison et al. reported that patients saw increases in executive function, attention, speed of processing, and memory while taking vortioxetine. This is consistent with studies in aged mice, whose cognition improves more on vortioxetine than on the SSRI fluoxetine, according to researcher Yan Li and colleagues.
Omega-3 fatty acids (especially the type known as DHA) are essential for brain development and functioning, but most people eating a modern western diet consume low amounts of these compared to omega-6 fatty acids. Omega-3s are anti-inflammatory while omega-6s are pro-inflammatory. A large UK study published in the journal PLOS One in 2013 reported that healthy 7- to 9-year-olds with lower levels of omega-3 long-chain polyunsaturated fatty acids in their blood (including DHA, DPA, and EPA) had lower reading ability and working memory, and also had more behavior problems.
The oils in fish are the best source of omega-3 fatty acids, and most of the children with poor reading ability in the study fell short of the UK nutritional guideline that recommends eating two portions of fish per week.
Girls in the study had more dramatic deficits in omega-3 levels than boys. In adults, women tend to metabolize long chain polyunsaturated fatty acids more easily than men, but this difference is driven by hormones, and because the girls in the study had not yet reached child-bearing age, they did not reflect this benefit.
Omega-3 deficits in children have been connected with attention deficit hyperactivity disorder (ADHD), and supplementation with extra omega-3 fatty acids in the diet has led to improvements in ADHD.
Choline Treatment For Pregnant Mothers And Newborns Improves Babies’ Cognition and Normalizes a Risk Factor for Schizophrenia
Deficiencies in GABA inhibition have been linked to the risk of schizophrenia (and perhaps bipolar disorder). GABA receptors are initially excitatory but switch to being inhibitory early in life. Choline derived from phosphatidylcholine or from eggs and meat in the diet is important in increasing GABA receptor development and maturity.
Ross et al. reported this year in the American Journal of Psychiatry that in a placebo-controlled study in which mothers took phosphatidylcholine in the last 2 trimesters of pregnancy (at doses of 3,600mg in the morning plus 2,700mg in the evening) and infants took 100mg/day for 12 weeks, the infants who received choline showed better neuronal inhibition than infants who did not receive choline on a P50 test of auditory evoked potential, in which the brain’s response to a series of beeps is recorded. An overactive P50 response is a sign of deficiencies in GABA inhibition.
In infants with a common gene variant in the alpha 7 nicotinic receptor that makes it function less well (which also may be a risk factor for the development of schizophrenia), the choline regimen normalized the P50 test, while placebo had no effect. However, in a recent study by Cabranes et al. published in Psychiatry Research, there was no association of the alpha 7 gene variant and schizophrenia or bipolar disorder, although patients with bipolar disorder and patients with schizophrenia did perform differently on the P50 evoked potential test than controls did.
Editor’s Note: In an editorial by Judy Rapoport that accompanied the Ross et al. study, the difficulty of using the findings in clinical practice are discussed. Meck et al. showed in 1999 that choline supplementation enhanced spatial memory, and in several cases nutritional supplements can have beneficial effects on the brain. Rapoport notes the success of perinatal folate in preventing neural tube defects and the likelihood that Vitamin D supplementation can prevent some cases of schizophrenia.
However, extrapolating the choline findings of Ross et al. to clinical practice, especially given the lack of association of the alpha 7 gene variation to psychiatric illness in the study by Cabranes et al., might be premature. Instead, Rapoport recommends a good diet and prevention of infection as first steps for treatment. Choline supplementation would be roughly equivalent to three eggs a day.
In a review article in the Neuroscientist published in February of this year, Kirk I. Erickson and collaborators wrote that “[m]ajor depressive disorder is considered a risk factor for Alzheimer’s dementia and memory impairment and is associated with less BDNF and greater hippocampal atrophy, possibly through a BDNF pathway. However, exercise and effective treatment for geriatric depression increases BDNF levels, increases serotonin fibers, is associated with greater hippocampal volumes, and reduces the risk for Alzheimer’s dementia.”
Editor’s note: Not a bad set of benefits from exercise! The researchers suggest that exercise is extremely important in reversing the decreases in brain-derived neurotrophic factor (BDNF) associated with depression, helping to improve depressed mood, increasing cardiovascular fitness, and maintaining healthy cognition.
Hippocampal volume and BDNF levels in blood both decrease with age. Yet exercise increases both BDNF and the formation of new neurons (neurogenesis) in animals. New data in humans suggest that aerobic fitness is associated with the size of the hippocampus, both in both children and adults. It is not clear yet whether this increase in hippocampal volume is directly driven by increases in BDNF and/or neurogenesis. However, since a smaller hippocampus is a risk factor both for depression and for mild cognitive impairment progressing to Alzheimer’s dementia, attempting to enhance hippocampal volume in any way possible is probably a good idea.
Methods of increasing hippocampal volume include treatment with antidepressants or with lithium. In the 2012 paper Erickson and collaborators also wrote, “Anaerobic exercise enhances executive and memory function and reduces hippocampal atrophy in late adulthood, and this may be partially mediated through a BDNF pathway.”
Erickson and collaborators conducted a longitudinal study published in 2010 that quantified the amount of physical activity subjects engaged in by calculating the total number of blocks walked per week. Individuals reporting greater amounts of physical activity at the beginning of the study had, upon examination nine years later, greater gray matter volume in several parts of the brain, including the hippocampus. This effect was “dose-dependent,” meaning that only those individuals who walked at least 72 blocks per week (roughly equivalent to 1 mile per day) had significant sparing of brain tissue nine years later. The study found increased gray matter volume in the prefrontal cortex and in the temporal lobe.
After a further follow-up of four more years, greater gray matter volume with physical activity was associated with a two-fold reduced risk of cognitive impairment. The researchers concluded that “physical activity patterns earlier in life were linked to brain volume and cognitive impairment later in life.”
There are a number of important points to remember about cognitive impairment. One is that increasing hippocampal volume and preventing its decrement with aging may help prevent age-related memory loss and potentially the rapidity at which mild cognitive impairment progresses. Read more