2005 overview: Significant clinical developments within affective disorders

Since World War II it has been suggested that the incidence rate of depression has been increasing, and it has been hypothesized that the modern way of living in a more changeable and stressful society may induce depressive states.

On the basis of such suggestions the World Health Organization (WHO) has estimated that depression will rise to the second leading cause of disability and early death (DALY) in 2020. However, only few longitudinal studies on the incidence of depression have been undertaken and results have often been influenced by methodological drawbacks.

The Lundby study

The Lundby study started in 1947 and has now been ongoing for more than 50 years (ref. 1). The results suggest that the trend of increasing rates of depression has terminated in Sweden as lower rates were found for both men and women in recent times. The diagnostic criteria for depression used in the study have remained the same over the years and correspond quite well with the DSM-IV diagnoses for major depression.

Furthermore, researchers who had done some of the prior fieldwork were supervisors for the new interviewers increasing continuity of the method. Multiple sources of information such as case notes, registers and key-informants may have helped to reduce recall bias.

Better socio-economic status

Although methodological explanations of the decreasing incidence rates cannot be excluded other explanations seem reasonable to consider. A possible explanation may be that health has increased in Sweden due to a better socio-economic status in 1972 than previously.

In the period from 1947 to 1997 several changes have been taken place in the Swedish society such as urbanization, changes in family structure, institutionalization of care for children, etc. It does not seem from the present results that such factors may increase stress or the susceptibility to stress and increase the risk of developing depression eventually. 

High prevalence rate

On the other hand, other studies presented in 2005 using DSM-IV criteria have now confirmed the high prevalence rate of mental disorders in general found in the early epidemiological studies from the 80's and early 90's (28.1% in the ECA study (ref. 2) and 29.5% in the NCS study (ref. 3)).

However, the studies also revealed that only 60% of these disorders are of moderate to serious severity corresponding to 14% of the population (ref. 4). Anxiety disorders are the most common disorders with a twelve-month prevalence of 18 % and mood disorders are the next most common disorder with a prevalence of 10%.

The 12-month prevalence of Major Depressive Disorder (MDD) was 5.3% (3.6% for men and 6.9% for women) (ref. 5). On average, the depressive disorders were of a rather severe clinical significance with a long duration of episodes, frequent suicidal thoughts, frequent psychiatric comorbidity and a high risk of recurrence.

Thus, the mean age at onset was 30 years, the median duration of the longest depressive episode was 24 weeks and with a mean of 4.7 depressive episodes. Nearly half of subjects with major depression wanted to die, more than a third thought of suicide and 9% had attempted suicide.

Frequent psychiatric comorbidity

Psychiatric comorbidity was frequent with 38% suffering from any personality disorder, 36% from any anxiety disorder and 14% of any alcohol use disorder during 12 months. Subjects, who were widowed, separated or divorced, or were newer married and subjects with low personal income had higher rates of depression.

Despite suffering from a serious disorder, 40% of the responders did not report that they had received any specific treatment for the disorder. 

Bipolar disorder in primary care

Another important issue highlighted in 2005 is the high prevalence of bipolar disorder among patients seeking primary care (ref. 6). As with depressive disorder, bipolar is often overlooked by doctors, and further bipolar is often misdiagnosed as unipolar disorder.

Treating patients with depressive or anxiety disorders with antidepressants without recognising hypomania or mania in the past may increase the risk of inducing manic episodes and switching. For this reason it is recommended that patients with bipolar disorder always get a mood stabilizer such as lithium when they are treated with antidepressants.

9.8% screened positive

The study by Das and colleagues (ref. 6) included a systematic sample of consecutive adult patients aged 18 to 70 years seeking primary care and found that 9.8 % (112) of 1157 patients were screened positive for lifetime bipolar disorder using the Mood Disorder Questionnaire (MDQ).

Among the 112 patients, 72.3% had sought professional help for their symptoms, but only 9 (8.4%) reported receiving a diagnosis of bipolar disorder. 68.2% of the 112 patients had a current major depressive episode or an anxiety or substance use disorder and only 6.5% reported taking a mood-stabilizing agent in the past month.

Patients who screened positive for bipolar disorder reported worse health-related quality of life as well as increased social and family life impairment compared with those who screened negative.

More attention needed

Prior studies have also shown that among patients diagnosed with unipolar disorder in private psychiatric practice, a large proportion actually suffers from bipolar disorder according to research diagnoses. Thus taken together with the Das et al. study (ref. 6), it seems that more attention toward diagnosing bipolar in clinical practice is needed.

The Mood Disorder Questionnaire (MDQ) has a high sensitivity for bipolar disorder, although specificity and sensitivity of the questionnaire has not been tested in primary care, and patients can easily field out in a few minutes while sitting in the doctors' waiting room.

Studies conducted during 2005 have shown that severe depressive and bipolar disorders are often overlooked and misdiagnosed. There is a great need for more attention to depressive as well as bipolar disorder among patients, relatives, doctors and society in general.

References

1. Mattisson C, Bogren M, Nettelbladt P, Munk-Jorgensen P and Bhugra D. First incidence depression in the Lundby Study: a comparison of the two time periods 1947-1972 and 1972-1997. Journal of Affective Disorders 2005; 87 (2-3); 151-160

2. Regier DA, Kaelber CT, Rae DS, Farmer ME, et al. Limitations of diagnostic criteria and assessment instruments for mental disorders - Implications for research and policy. Archives of General Psychiatry 1998; 55 (2); 109-115

3. Kessler RC, McGonagle KA, Zhao S, Nelson CB, Hughes M, Eshleman S, et al. Lifetime and 12-month prevalence of DSM-III-R psychiatric disorders in the United States. Results from the National Comorbidity Survey. Archives of General Psychiatry 1994; 51 (1); 8-19

4. Kessler RC, Chiu WT, Demler O, Merikangas KR and Walters EE. Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry 2005; 62 (6); 617-627

5. Hasin DS, Goodwin RD, Stinson FS and Grant BF. Epidemiology of major depressive disorder: results from the National Epidemiologic Survey on Alcoholism and Related Conditions. Archives of General Psychiatry 2005; 62 (10); 1097-1106

6. Das AK, Olfson M, Gameroff MJ, Pilowsky DJ, Blanco C, Feder A, et al. Screening for bipolar disorder in a primary care practice. JAMA 2005; 293 (8); 956-963 (Free full text article)