Saturday, November 19, 2016

Chronic Conditions and Major Depression

When I was training (many years ago) in Psychiatry, all of the textbooks used to have long lists of medical conditions that could "cause" depression. The idea was that such lists would serve as a reminder that physical causes should be considered when assessing patients. For example, if there was a reason to suspect hypothyroidism, then that patient's thyroid should be checked. However, in current times this way of thinking - that depression would be distinguished as being "caused" by a physical OR a psychological cause seems very simplistic. Certainly, there are physical mechanisms that could link some chronic conditions to depression, but every chronic condition can have psychological and social implications too. Depression likely arises as a result of the multiple contributing causes in every case, not a different single cause in different cases. We recently conducted an analysis of national survey data to look at patterns of association between major depressive episodes and various chronic medical conditions. The meta-analysis (published here) uncovered three previously undescribed patterns of association. First, we found that most conditions are more strongly associated with depression in younger people. This effect was most prominent for high blood pressure and cancer. I believe that this probably indicates that developing such a condition is more stressful and threatening for a younger than older person. This is of course mere speculation. This was not a universal pattern. Migraine was an exception: the strength of association increased with age, especially in men. Second, especially for conditions predominantly affecting older age groups (arthritis, diabetes, back pain, cataracts, effects of stroke and heart disease) an epidemiological occurrence called confounding (by age) was evident. Because depression prevalence diminishes with age, and because these conditions affect older people, statistical adjustments were needed to see the true association. Finally, a surprising result was that thryoid disease, long considered the "classical" physical cause of depression, was only weakly associated with depression, and only in women. Epilepsy, had a unique pattern than didn't depend on age or sex. 

Wednesday, October 12, 2016

Major Depression is More Common in More Northerly Latitudes in Canada

Major depression is thought to be more common in the winter than the summer months in Canada (e.g. follow this link), and changing circadian patterns are believed to have a role in this. It has sometimes been suspected that there would be a north-south latitude gradient as well. However, the small number of studies that have looked at this have failed to find an association, see Partonen et al. and Grimaldi et al.  Using data from many large scale Canadian surveys, were able to examine this association with a much larger sample size than was previously possible. These surveys included a measure of past year major depressive episodes called the Composite International Diagnostic Interview, Short Form and by linking to postal code files we were able to determine the approximate latitude of each respondent. A small gradient was found, with more northerly latitudes having a higher prevalence. A link to be the abstract is available here. It is possible that the etiology of such depression is related to factors such as sunlight exposure or shifting circadian patterns with more northerly latitudes. Of course, the difference could also be due to social determinants. Additional studies will be needed to determine this, but with adjustment for many potential determinants (age, sex, marital status, income, education) the association persisted. These results may contain clues to understanding the causes of depression more clearly, but they certainly also have implications for planning health services in more northerly places.

Tuesday, July 19, 2016

Major depression is more prevalent in urban areas of Canada

Understanding how depression prevalence varies by person, place and time variables can help to plan for services and also generate hypotheses for future research. With respect to planning services an important question is whether there is more depression in urban or rural areas. The evidence so far has been mixed, with a few studies finding an association and others not. A recent analysis of data from a series of Canadian Community Health Surveys was able to incorporate a larger number of observations than any previous study and to settle the issue. The answer is that depression prevalence is about 20% higher in urban areas. This is not a large difference. Some risk factors such as childhood adversities are associated with an approximate doubling (100% increase) in prevalence. Indeed the modest effect of urban living probably explains the previously inconsistent literature. Analyses of individual surveys probably lacked power to detect it. However, from the point of view of planning services, a 18% difference is not trivial. Why would the prevalence be higher in urban areas? There are many possible explanations. One is that the environment there may convey a higher risk of becoming depressed (aka a higher incidence of depression), however, a longer duration of depressive episodes or lower mortality (e.g. due to suicide) in urban areas could also explain it. Finally, migration of depressed people from rural to rural areas is another possible reason for the difference. This work has been published in the Canadian Journal of Psychiatry, a link to the abstract is available here.

Tuesday, March 29, 2016

Stigma is perceived as often by people with depression as by people with schizophrenia

A 2012 mental health survey conducted in Canada (called the Canadian Community Health Survey-Mental Health or CCHS-MH) included a brief interview module designed to assess perceived stigma among those accessing mental health services. The module was called the Mental Health Experiences Scale, developed by Dr. Heather Stuart, at Queens University. The CCHS was a large survey, with a sample size of > 25,000 respondents. It employed a sophisticated sampling design to ensure representation of the national household population. However, the stigma scale was only administered to a subset (an estimated 8% of the population) who reported accessing mental health services in the preceding year. However, the questions in the scale asked about perceived stigma from any source, not just health professionals. About one in four of these respondents reported encountering stigma. The survey also included measures of mental health status, such as perceived mental health, a distress scale, self-reported diagnosis and a structured diagnostic interview. People with diagnoses were more likely to report stigmatization (irrespective of whether the diagnoses were from the diagnostic interview or from a health professional). Surprisingly, the frequency of perceived stigma was almost as high in people with mood and anxiety disorders as among people with Schizophrenia. Similar to previous studies, the perception of stigma was found to be lower in older respondents, over the age of 55. It is often assumed that stigma results from labelling, or that labelling is an essential component of the process of stigmatization. In this regard, an interesting finding was that people who reported receiving no diagnosis still often reported stigmatization, especially if they had symptoms suggestive of a diagnosable disorder (e.g. high distress, pronounced depressive symptoms). This suggests that stigma can occur directly as a result of manifestations of mental health difficulties, without the need for a diagnostic label. The paper is available here

Sunday, March 6, 2016

Adverse Childhood Events and Subsequent Health Outcomes

In this study, information gleaned from a sample assessed during childhood and then subsequently followed in an adult health survey was used to assess adverse health outcomes associated with adverse childhood events (ACEs). Some studies have suggested that many adult health outcomes are associated with ACEs. For example, cardiovascular disease may have a higher risk in people exposed to ACEs as children. However, such associations are not fully confirmed. Most such studies are based on retrospective reports of ACEs, and retrospective recall is not very reliable. It is possible, for example, that people with more adverse health outcomes during adulthood are more likely to report or remember childhood adversities. Many of these studies have used clinical samples - and ACEs may affect health care use, which could distort the associations. If such associations exist (e.g. cardiovascular disease) it is likely that they occur through complex pathways, e.g. if ACEs increase the risk of depression, this may lead to higher rates of other behaviours (e.g. dietary and lifestyle factors) that may in turn increase the risk of cardiovascular disease. For these reasons, we recently sought to link survey that collected data from the same people during childhood and adulthood in representative community samples and to look at proximate changes that occur in relation to ACEs (i.e. changes that are evident in young adulthood). We found the most convincing evidence of associations for three inter-related outcomes and ACEs:  Major depression, psychotropic medication use and smoking. The abstract is available here. This study provides some insights into the early life impact of ACEs and suggests and smoking, especially, may be a link connecting ACEs to later health difficulties.

Tuesday, February 2, 2016

The duration of depressive episodes - one of the reasons that screening may be a bad idea

Depression is common and sometimes undetected. This has led to a continued interest in screening for depression. The assumption behind screening is that there must be a lot of people who meet criteria for a depressive episode and who could be benefit from treatment, except that they have not sought treatment because they don't know that they are depressed. A screening scale such as the PHQ-9 could possibly assist with the identification of these episodes, leading to initiation of treatment and hopefully better outcomes. However, there are some unexpected drawbacks of depression screening in practice. One is that these scales produce false positives. For example, if a scale such as the PHQ-9 is roughly 80% specific, this means that 20% of people without depression will screen positive. These would need to be assessed along with other positive results, resulting in an inefficient use of resources. A related problem is that many depressive episodes are mild and self-limited. These episodes will resolve on their own. This wouldn't necessarily be a big problem for screening except that most new episodes (the ones that screening would presumably try to detect) ARE brief. This is an under-appreciated fact since in the population the average episode is about 3-4 months. However, this average is a mixture of many brief episodes and a smaller number of longer episodes - so that screening is likely to divert resources towards those with lower levels of need, or those with no treatment needs at all. This dynamic is hard to conceptualize, but I've made animation, part of a paper published in 2006, to illustrate it. In the animation the people depicted with lighter coloured shirts have brief episodes but those with darker shirts (longer episodes) predominate in the population of people with episodes because they stay longer in the population. The most effective intervention would be to help those with longer episodes recover faster through treatment as opposed to earlier detection through screening. You can see the animation here.

Wednesday, January 27, 2016

Health professionals can take the fight against stigma into their own back yards

Today is Bell Lets Talk day - in which tweets with #BellLetsTalk lead to a donation from Bell to support its stigma-fighting efforts. There is lots of support for the fight against stigma - usually targeting public stigma (negative attitudes help by the general population). Health professionals almost always have good intentions, but they are not immune from stigma. A recent study (report available here) identified 6 key ingredients of efforts to fight stigma among health professionals: (1) the anti-stigma intervention should include a personal testimony from a trained speaker who has lived experience of mental illness, (2) there should be multiple forms or points of social contact (for example, a live speaker and a video presentation, multiple speakers, etc.), (3) the program should focus on behaviour change by teaching skills that help health care providers with concrete skills to help them avoid stigmatization, (4) that the program should challenge stigmatizing myths, (5) the program facilitator should be enthusiastic and have a person-centred approach (as opposed to pathology-first) and (6) the program should emphasize recovery as a key part of its messaging. Often, health organizations and institutions plan their own anti-stigma interventions "from the ground up" but they should carefully consider these key ingredients. Programs that incorporate all of them have better outcomes. 

Tuesday, January 26, 2016

Benzodiazepine use in Canada

Benzodiazepines are sometimes used in the symptomatic management of major depression - usually targeting symptoms such as anxiety and sleep problems. Unfortunately, with any use of these medications for longer than a few weeks there can be development of tolerance, such that rebound anxiety and insomnia may occur on discontinuation, making it difficult to stop them. For this, other reasons, the prevalence of use of these drugs has been persistently high over the past several decades, as discussed in a paper by Kassam et al., available here. In the February edition of the  Canadian Journal of Psychiatry, we compare two mental health surveys conducted in Canada - one in 2002 and one in 2012. One of the positive changes over this ten year period is a decline in the frequency of benzodiazepine use in the general population, down to 1.5% whereas this was previously about 3%. While this is good news, it is possible that the use of benzodiazepines has merely been replaced to some extent by the use of sedating antipsychotics such as quetiapine, where an increase in the frequency of use was observed.

Sunday, January 24, 2016

Blended learning for Community Health Workers and Health Professionals in Afghanistan

Funded by Grand Challenges Canada, Tech4Life in partnership with some Canadian academics through the University of Calgary have been developing blended learning materials for front-line mental health workers in Afghanistan. They use the open-source learning platform Moodle and have also employed some innovative strategies such as providing memory cards with the course materials to the learners. They have recently reported positive outcomes from the evaluation of their modules on Depression - and more detail should soon be forthcoming in the peer-reviewed literature.

Sunday, January 17, 2016

The "Blue Monday" phenomenon - not just stupid anymore, this is getting destructive

It is not really any secret any more than "blue monday" is a fake. This was an idea that was apparently developed as a component of a marketing scheme for a travel company (the story can be found on Wikipedia, here). It comes with a ridiculous formula that adds, subtracts, multiplies, divides (it even has exponents!) various things that intuition suggests might make the first few weeks of the new year unpleasant. It might be funny except that in spite of all reason it continues to be mistaken for legitimate science - most recently our own CBC has decided to conflate this idea with the the concept of seasonal affective disorder, look at this story. This one is not as bad as some media outlets, who seem to be completely sucked in, see here for example. Apparently, there is even a saint that you can pray to for assistance. This might all be humorous (for a fun discussion, check here), except that there are number of downsides. Pseudoscience has the potential to discredit actual science and the "Blue Monday" concept has the potential to stigmatize and trivialize actual depression, as recently pointed out in a blog by George Woolfrey. As Tom Chivers says, here, "can't we all just drop it now?" Sensible as that suggestion may be, I doubt it.

Wednesday, January 13, 2016

Depression is much more common in the winter in Canada

Discussions about winter depression in this country tend to gravitate towards the concept of Seasonal Affective Disorder (SAD). SAD is not officially recognized as a disorder in DSM-5, but is instead a subtype of Major Depressive and Bipolar Disorders. The way in which the sub-type is defined in the manual is based on episodes having a characteristic time of onset and resolution. They are not required to occur in the winter and they are not even required (in the case of Bipolar I disorder) to be depressive episodes. Most studies of this condition have used instruments that assess seasonal variation in mood, not depressive episodes. But it is important to know whether there is actually more major depression in the winter months. We've recently looked at this question in national datasets and the results are striking (click here). The paper is published in the journal Epidemiology and Psychiatric Sciences. There is a 70% higher odds of depression in the winter months compared to the summer months. This presents a real problem for the health system(s) in Canada to deal with, since it implies a need for greater availability of services in the winter months - and I know of no efforts to deliver seasonal services for depression.

Tuesday, January 12, 2016

Is depression more common in women? Yes, but...

It is commonly asserted that major depression is more common in women than in men - with (roughly speaking) a 2:1 ratio in the prevalence. However, what is often forgotten is that this sex difference is age-dependent. It does not seem to exist prior to puberty. This raises the question of what happens later in life as people get older. We have recently examined this question using data collected from approximately half a million people in Canadian national surveys conducted over the past two decades. The results confirm this strong age dependency - the sex difference is largest in the youngest age group examined by these surveys (15 - 24 years) and subsequently gets smaller with age. By the elderly end of the age range the difference is gone completely. The abstract from this study is available through this link. Prior researchers have hypothesized the sex difference would disappear around the age of menopause, but this does not appear to be the case. Rather, the biggest difference is in the 15-24 age group and it gets progressively smaller with time. It is important to note that in addition to being more common in women throughout much of the age range, major depression is more common in the younger end of the adult age range. As such, it is not so much that men "catch up" with women as that the prevalence diminishes with age at a more rapid rate in women. It is fascinating to wonder what the reasons might be, and whether these are biological, psychological or social (or all of these) in nature.