 A further complication about the rationality of suicide is the evident link between suicidal thoughts and mental illnesses such as depression. Some studies of suicide indicate that over 90% of suicidal persons displayed symptoms of depression before death, while others estimate that suicide is at least 20 times more common among those with clinical depression than in the general population. In cases of suicide linked with depression, individuals’ attitudes toward their own death are colored by strongly negative and occasionally distorted beliefs about their life situations (career prospects, relationships, etc.). As Brandt (1975) observed, depression can “primitivize one’s intellectual processes,” leading to poor estimation of probabilities and an irrational focus on present suffering rather than on possible future goods. Such findings provide evidence that suicidal behavior is typically, though not necessarily, irrational.