It has long been suggested that younger and older suicides may be different entities.43,44,111,112,113,114,115,116,117
However, it remains to be better investigated whether suicide is the same phenomenon across the life cycle or whether it has a different meaning and set of risk factors when it occurs in childhood or in older age. Unfortunately, most researchers studying suicide have viewed age as a confounding variable to be controlled for, rather than as a variable of interest.118
As a result, most data available regarding age differences in suicide come from post hoc comparative analyses of unselected suicide samples.
The Finnish National Suicide Prevention Project provides some clues to this question.37,104,119
This large-scale study collected information about all suicides committed in Finland over a period of 1 year between 1987 and 1988. A total of 1397 cases were studied by means of psychological autopsies. Their findings suggest that suicide in young subjects may be a different phenomenon from suicide later in life. Accordingly, the psychiatric profiles of these 2 groups seem to be different. Major depression is significantly more common among older people who commit suicide,116
whereas the presence of axis II comorbidity is more often observed in younger people who commit suicide.30,116
Other psychological studies confirm these observations, indicating that a considerable percentage of elderly suicide cases (> 55 yr) meet criteria not only for major recurrent depression but also for other chronic depressive conditions such as dysthymia.120
Conwell et al120
also found that youthful suicide was different from elderly suicide because the former was associated with more substance abuse or dependence, a finding that is supported by psychological studies in young completers.105,108,121,122
Studies indicate that an important proportion of elderly people who commit suicide have made a previous suicide attempt.118
Consistent with this notion, studies in elderly attempters suggest that subjects with early onset of major depression have a higher chance of presenting suicidal behaviour.123,124
These observations are in agreement with data from a prospective long-term follow-up study by Angst et al,125
who observed that the cumulative risk of suicide continued to increase with successive episodes of the illness. On the other hand, studies of suicidal behaviour in young patients suggest that the risk of suicide attempts does not seem to be randomly distributed in the course of the disorder. In other words, young patients who attempt suicide often do so early in the course of the disease.126
Indeed, this is also consistent with data from psychological autopsies in our sample of young suicide completers, which indicate that among subjects diagnosed with major depression, almost 60% of the individuals committed suicide during the first episode of the illness. Therefore, these results seem to indicate that suicidal behaviour has a different “natural history” in younger and older subjects, even when the underlying psychopathology is similar. Thus, in our study comparing depressed suicides with depressed controls described earlier,40
an important age effect was observed, suggesting that impulsive–aggressive behaviours play a substantial role primarily in young suicide completers. Conversely, among unselected suicide completers, the presence of impulsive–aggressive behaviours is more likely to be observed among younger than among older suicide completers (Zouk et al., unpublished observations, 2005) and, interestingly, when impulsive and nonimpulsive suicides are compared, no differences are found in rates of associated mood disorders.
Further data suggesting the different role of impulsive–aggressive behaviours and possibly the different nature of youthful and elderly suicide come from studies by Conwell et al.118,120
These authors assessed age differences in behaviours leading to completed suicide and found that older age was significantly associated with more determined and planned self-destructive acts, less violent methods and fewer warnings of suicidal intent. Taken together, these results seem to suggest that young and elderly subjects who commit suicide have different diatheses. Indeed, there is support for the notion that younger suicides are more likely to be the result of an impulsive–aggressive act, often facilitated by alcohol or drug intoxication, or both, in subjects who have a pervasive problem in their personality structure and are affected by an axis I disorder. Moreover, this tragic event is frequently associated with a stressful life event, which in itself frequently seems to be associated with the subject's underlying personality traits. On the other hand, elderly suicide is more often the consequence of a planned, less impulsive act often in a physically ill and depressed subject, who has been enduring difficult life events that are more commonly related to the medical illness or to events that are intrinsic to the age group.