Aerobic Exercise, Resistance Training and Mortality

The research support for regular exercise to be associated with reduced risk of death is growing.  However, there is limited research that focuses on effects of aerobic versus strengthen (resistance) training.  Additionally, there is limited data comparing mortality in those with and without a general medical condition. 

Schoenborn and Stommel recently published a study addressing these issues in teh American Journal of Preventive Medicine.  They examined a large sample of U.S. adults and assessed whether they met  the 2008 USDHHS Activity Guidelines for Americans:

• 150 minutes per week of moderate intensity aerobic activity
• OR 75 minutes per week of high intensity aerobic activity
• Encourage two days per week of weight training of 7 large muscle groups

The study examined exercise levels and mortality by linking data from the 1997-2004 National Health Interview Survey and death registry data from 1997-2006.  Mortality examined in groups with no chronic medical conditions compared to those with one or more medical conditions including: diabetes, hypertension, vascular problems, lung disease (asthma/bronchitis), one or more functional limitations (any difficulty walking, climbing steps, standing, sitting, stooping, reaching, grasping, or lifting/pulling or pushing large objects).

This study was informative because it looked at the effect of aerobic versus strength versus both aerobic and strength on mortality.  Additionally, it examined the effect of exercise on mortality in four age categories: 18 and younger, 18 to 44 years of age, 45 to 64 years of age and 65 and older age groups.

>The key findings from the study were:

• Strength training alone was not associated with decrease mortality risk
• Aerobic exercise was linked to reduced mortality risk aerobic exercise with over 150 minutes per week somewhat better than less than 150 minutes per week ( although going above 300 minutes per week did not correlate with additional mortality reduction)
• Among those meeting aerobic exercise guidelines, adding strengthening showed a trend for correlation with an additional beneficial  mortality effect
• Older adults  with one or more chronic conditions appeared to have the strongest association between exercise and lower mortality risk

The chart below summarizes the magnitude of association between exercise levels and lower mortality rates in those in the 45 to 64 age category and those aged 65 and older with one or more medical conditions.  To aid in interpretation of the numbers the SMR for those 65 and older with one medical condition meeting both aerobic and strengthening exercise guidelines was .52.  This means during follow up they were 48% (1-SMR) less likely to die than those not meeting exercise guidelines for either aerobic or strengthening types.

This study is a correlational study and not a prospective controlled trial so the data need to be interpreted cautiously.  It may be that individuals with chronic medical conditions die not because they don't exercise but because their illness is so severe they are unable to exercise.  Nevertheless, this study adds to our knowledge of the relative correlation of aerobic and resistance training and mortality.  Additionally, it suggests that exercise may have a significant beneficial role in older adults who have one or more medical conditions.

Figure by author adapted from data provided in manuscript.

Schoenborn, C., & Stommel, M. (2011). Adherence to the 2008 Adult Physical Activity Guidelines and Mortality Risk American Journal of Preventive Medicine, 40 (5), 514-521 DOI: 10.1016/j.amepre.2010.12.029

Ethical Challenges in Neuroscience

Dr. Nuala Kenny presented the December 2010 Warren Frontiers in Neuroscience lecture at Laureate Psychiatric Hospital and Clinic in Tulsa, Oklahoma.  Dr. Kenny is a physician trained in pediatrics with a long interest in ethics.  She formed the Department of Bioethics at Dalhousie University in Nova Scotia, Canada.  Her presentation was titled: “Brain, Mind and the Moral: Challenges of Neuroethics”.  Several scientific publications cited in her presentation are referenced at the end of this commentary.  The following are my lecture notes:

Ethics in neuroscience or neuroethics is an important topic given the explosion in basic science as well as clinical research in neuroscience.  The neuroethics field has grown over the last decade.  Despite the development of neuroethics there is no widely accepted definition of the term.

Oklahoma is an appropriate location for a presentation on this topic.  One might say that ethics in neuroscience got started “On the wrong hoof” in Oklahoma.  Dr. Lewis “Jolly” West, the University of Oklahoma chair of Psychiatry in the 1960s performed research funded by the CIA in their portfolio of LSD research and mind control.  Dr. West famously performed an experiment on an elephant where a large bolus of LSD resulted in the collapse of the animal, seizures and death.  Not a great starting point.

Modern bioethics grew in the 1960s based on technological advances in medicine (dialysis, mechanical ventilation, transplantation) and research.  The key initial areas included issues of consent, competence, determining the risk-benefit ratio of treatments and research protocols, and the issue of justice.  Out of this work came the four key principles of medical ethics 1.) autonomy, 2.) beneficence- doing the most good, 3.) non-malfeasance—limiting risk of harm and 4.) justice.  Although these principles are helpful in addressing ethical review on an individual case basis, they do not aid in more global discussion of ethics such as that necessary in neuroscience.

A 2002 conference sponsored by the Dana Foundation in California set out an agenda to “Map the Field” of ethics in neuroscience and identified four key areas of importance—these areas are reviewed with some comments on interval neuroscience research developments:

Therapeutic interventions

• Screening has developed that allows the diagnosis of clinical neuroscience disorders where no treatment is available—how do we wisely use this technology?
• fMRI may be able to identify children and adolescents  at high-risk for developing conditions such as schizophrenia—how should this information be used and discloses
• Treatments such as deep brain stimulation in Parkinson’s disease can dramatically reduce the motor symptoms of the condition, but may result in more disinhibited behavior and reduced decision-making ability.  How do we assess risk-benefit ratios in these types of interventions

Social policy

• Advance imaging techniques provide a wealth of information about the brain and brain function.  Imaging is commonly combined with genetic information for more powerful experiments.  Imaging technology is now available to combine two types of imaging at once (see combined MRI/PET image above). What are the key neuroethical issues involved in these more powerful imaging technologies?
• Cognitive enhancement drug research is underway the can improve concentration, memory and alertness in normal individuals.  What should be the limitations in the use of these drugs—are we devaluing normal human imperfections that define use?

Public education

• Science education is hard and neuroethics education equally hard—How do we best inform the general public on these issues?
• The media have significant power in shaping what the public knows in developing brain science and the ethical implications.  The media loves neuroscience and brain research breakthrough.  Does the media have an interest in a thoughtful discussion of the neuroethics involved in this research?

Implications of neuroscience in self, agency and moral responsibility

• Neuroscience stimulates thoughtful re-analysis of key ethical issues such as the self, agency (authenticity) and moral responsibility.  There is a strong element of neuroreductionism in some neuroscience research, i.e. “ I am what my neurons and synapses are doing”.  We need to be careful about this approach and the tendency for mind-brain dualistic thinking
• Neuroscience is focusing on how the brain makes ethical and moral decisions.  This reversal challenges ethicists to stay up-to-date on functional MRI and other brain imaging research advances in decision making, variability in processing ethical information, lying and cognitive control in psychopathological behavior.

Brain Posts Comment:  This presentation does highlight some of the key ethical challenges for basic and clinical neuroscientists.   There will need to be emphasis on public education in neuroethics and continuing study and discussion of neuroethical implications as imaging technology is more widely implemented.  You can learn more about the topic of neuroethics at this Dana Foundation website.

Image of combined PET and MRI scans from unrestricted public domain image by author Mco44.  

West LJ, Pierce CM, & Thomas WD (1962). Lysergic Acid Diethylamide: Its Effects on a Male Asiatic Elephant. Science (New York, N.Y.), 138 (3545), 1100-3 PMID: 17772968

Leentjens AF, Visser-Vandewalle V, Temel Y, & Verhey FR (2004). [Manipulation of mental competence: an ethical problem in case of electrical stimulation of the subthalamic nucleus for severe Parkinson's disease] Nederlands tijdschrift voor geneeskunde, 148 (28), 1394-8 PMID: 15291423


Young L, & Saxe R (2009). An FMRI investigation of spontaneous mental state inference for moral judgment. Journal of cognitive neuroscience, 21 (7), 1396-405 PMID: 18823250


Tairyan K, & Illes J (2009). Imaging genetics and the power of combined technologies: a perspective from neuroethics. Neuroscience, 164 (1), 7-15 PMID: 19409220

Seeking Depression Information on the Internet

The internet has grown as a source of health information for both clinicians and their patients.  Patients with mental disorders may be particularly drawn to using the internet for information due to the stigma associated with these disorders.  This makes it important for health educators to understand the demographic pattern of searches for health information including depression and other mental disorders.  A recent research study of those seeking information about depression provides some insight into the volume and pattern of web searches for "depression".  Fu et al conducted an interesting study that examined the number and pattern of internet searches for depression.  The authors used the following design in their study:

• Query for all AOL users web searches between March and May 2006
• Keyword depression with exclusion of obvious confounders, i.e. "great depression"
• Limited to U.S. AOL users
• Review of database of 21 million web queries.

The key results from their study included:

• 3 of every 1000 internet searches sought depression-related information
• 1.16 million search for "depression" estimated per month in the U.S.
• The most common search areas related to depression were 1. general information 28%, 2. identification/managment 18%, 3. pharmaceutical company depression website 11%, 4. depression-related psychiatric comorbidities, i.e. anxiety disorder or bipolar disorder 7%, 5. female and pregnancy-related depression 5%, 6. teen depression 5%, 7. suicide 0.6%.

This study probably underestimates the volume of internet searches related to depression as some individual likely type in the name of a depression drug or other more specific information in their query.

The authors note the volume of public searches for depression should stimulate high-quality education for the disorder.  Health educators with high-quality, evidence-based information should also work to keep their information at the top of search engine queries.  There is a significant amount of misinformation about depression and mental disorders on the internet.  There needs to be an effort to make sure individuals searching "depression" get to sites that provide them the information they need to help them make good decisions about their symptoms and disorders.

Here are some of the web sites that I feel provide high-quality evidence-based information for the general public:

National Institute of Mental Health
Mayo Clinic
WebMD
Google Health
Drugs.com
National Association of Cognitive-Behavioral Therapists

If you have personal experience with sites that you would like to recommend, feel free to post your recommendations in the comments section.

Pricky Pear from Enchanted Rock State Natural Area in Texas courtesy of Yates Photography.

Fu KW, Wong PW, & Yip PS (2010). What do internet users seek to know about depression from web searches? A descriptive study of 21 million web queries. The Journal of clinical psychiatry, 71 (9), 1246-7 PMID: 20923627