Although depression and suicide are highly related, one certainly does not imply the other. While some depressed persons may contemplate or attempt suicide, many people experiencing depression do not. Likewise, there are many factors other than depression that may put someone at risk for suicidal thoughts and actions. For example, patients with certain personality disorders, such as borderline personality disorder, may be at increased risk. Also, some tragic circumstances, such as financial loss, may cause someone to contemplate suicide.
While researchers interested in preventing suicide are usually also interested in preventing depression, it is important to treat it as a separate symptom, and consider that some types of depression involve suicidal thoughts while other types may not. We can’t assume that treatments for depression will also ease suicidality in everyone, as well.
A study recently published in The Journal of Affective Disorders examined a number of research studies on psychotherapy for depression and whether or not the treatments also reduced risk for suicide or hopelessness (which is a symptom highly related to suicidal thoughts). They didn’t find that there was sufficient evidence to show that this type of therapy reduced risk for sucidality. However, I believe this conclusion is mainly due to the lack of research on psychotherapy for depression which also includes outcome measures related to suicide and simply highlights the fact that research on depression therapy needs to consider suicide as a separate issue. While some therapies may treat depression successfully, which is great for the many people suffering from this mental illness, they may not be treating risk for suicide. We may find that other, targeted therapies are more appropriate for people with this risk.
In Australia, the National Suicide Prevention Program has been working tirelessly for decades trying to prevent suicide and provide resources to people at risk for suicide. Their site, Living is For Everyone (LIFE), is a great resource for the public and healthcare professionals, and includes information from a number of community organisations and government sectors: http://www.livingisforeveryone.com.au.