Depression remains a huge public health problem. It affects over two per cent of the adult population in the UK at any one time, and the World Health Organisation predicts depression will become the second most burdensome illness in the world by 2020.

The illness negatively affects people's ability to function and has both direct (via suicide) and indirect detrimental effects on people's physical health. Effective treatments, in terms of talking therapies and medication, already exist, but they need to be delivered to the people at risk. A key research priority, therefore, is to improve detection rates of depression.

According to a group of Taiwanese researchers led by Chao-Cheng Lin (National Taiwan University Hospital), GPs and other primary health care professionals are relatively poor at detecting depression, either because they lack the specialist skills needed, or because they are reluctant to label patients with a  mental illness.

Now Lin's team have developed and tested an internet-based screening tool for depression, which will allow people to carry out a preliminary depression diagnosis on themselves wherever there is access to a computer.

Their Internet-based Self-assessment Program for Depression (ISP-D) was placed on a large Chinese language mental health internet portal, PsychPark, where visitors were invited to complete the questionnaire. The tool takes people through a series of branching questions that can vary depending on prior answers. For example, one item asks if respondents have trouble sleeping every night. They can answer: 'No'; 'Yes, difficulty falling asleep'; 'Yes, early morning wakening'; 'Yes, waking up in the middle of the night'; and/or 'Yes, sleeping excessively'

A diagnosis of major depression, minor depression, sub-clinical depression, or no diagnosis, is then made based on the respondents' overall score on the test.

Overall, 579 people completed the ISP-D. It took them about ten minutes on average. They were then contacted two weeks later for a re-test. 184 people completed the re-test. Finally, participants were invited for a clinical interview with a psychiatrist, so as to test the validity of the on-line test. 55 participants agreed to this interview.

The researchers found that overall, the ISP-D showed respectable reliability. That is, there was good agreement between people's scores the first time they took the test, compared with the second time they took the test. More specifically, test-retest reliability was excellent for major depression and sub-clinical depression, but was poorer for minor depression.

The validity of the test was measured by comparing participants' online scores with the diagnosis made in a face-to-face diagnostic interview with a psychiatrist. Taking the psychiatrist's diagnosis as gold standard, this showed the ISP-D to be 76.4 per cent accurate, with a sensitivity of 81.8 per cent (i.e. that's the proportion of cases of depression identified by the psychiatrist that were also identified by the ISP-D) and a specificity of 72.7 per cent (i.e. the ISP-D produced an appropriately negative result for just over 70 per cent of cases that the psychiatrist found not to be depressed).

Chao-Cheng Lin and colleagues said these figures meant the ISP-D compared favourably to the reliability and validity of traditional pen and paper self-report depression screening tools, such as the Edinburgh Depression Scale, and clinician-administered tools such as the Hamilton Rating Scale for Depression. The researchers concluded their study showed the internet could provide people with a way to assess themselves for depression quickly and easily. 'The ISP-D provides a continuously available, inexpensive, and easily maintained depression screening method that is accessible to a large number of individuals across a broad geographic area,' they wrote.

The study did have some shortcomings, which were acknowledged by the researchers themselves. For example, the participants were inevitably self-selected, and tended to be young, single, well-educated women. Moreover, there was a relatively low response rate at re-test and at psychiatric interview. In fact, because only 55 participants attended interview, validity could only be tested for a diagnosis of major depression. These findings must therefore be treated with caution and demonstrate that further research is needed in the area and cultural variations assessed.

It must be remembered that this work is at an experimental stage, anyone with who feels that they have mental health concerns should visit their doctor or other health professional for assistance. There are many tests available that health professionals can use to diagnosis depression and then decide on the best course of therapy or treatment with the patient. For another example of a self-administered depression scale online, have a look at the test developed by the Black Dog Institute in Australia, an educational, research, clinical and community-oriented facility for the diagnosis and treatment of mood disorders. However, note that the Institute states that the tool is not intended to be a substitute for professional clinical advice.

Do you have a view on self diagnosis, or online testing for mental health problems? click on the comments link at the bottom and have your say   

Web links and further reading

The paper is freely available online:

Lin, C-C., Bai, Y-M., Liu, C-Y., Hsiao, M-C., Chen, J-Y., Tsai, S-J., Ouyang, W-C., Wu, C-h. & Li, Y-C. (2007).Web-based tools can be used reliably to detect patients with major

depressive disorder and subsyndromal depressive symptoms. BMC Psychiatry, 7, 12. http://dx.doi.org/10.1186/1471-244X-7-12

A Chinese-English translation of the test items is available at:

http://www.biomedcentral.com/content/supplementary/1471-244X-7-12-S1.doc

Key depression screening tools include:

The Beck Depression Inventory, originally developed in 1961 by Aaron Beck, was revised for a second time in 1996. The 21-item self-report scale focuses on the cognitive symptoms of depression. For the original scale, see http://www.geocities.com/psych_out_print_beck/Beck_AT_1961.pdf

The Hamilton Rating Scale for Depression was originally developed in 1960 by Max Hamilton. This is a 21-item clinician completed scale (also available with 17 items) that focuses more on the somatic symptoms of depression. For the original scale, see http://www.geocities.com/psych_out_print_hamilton/Hamilton_M_1960.pdf

For a review of the validity and reliability of the Hamilton scale, see Bagby, R.M.,

Ryder, A.G., Schuller, D.R., & Marshall, M.B. (2004). The Hamilton Depression Rating Scale: Has the Gold Standard Become a Lead Weight? American Journal of Psychiatry, 161, 2163–2177. http://ajp.psychiatryonline.org/cgi/reprint/161/12/2163

The Edinburgh Depression Scale, developed by L. Murray and J. cox in 1990. This is a 10-item self-report measure that was specifically designed to screen distressed women during pregnancy or during the post-natal period.

Black Dog Institute

For an example of a self-administered depression scale online, this test is developed by the Black Dog Institute in Australia. The Black Dog Institute is an educational, research, clinical and community-oriented facility on the diagnosis and treatment of mood disorders. The Institute states that the tool is not intended to be a substitute for professional clinical advice. http://www.blackdoginstitute.org.au/depression/howtotell/selftest.cfm