In fact, older people in particular have a number of factors working against them that appear to contribute to the incidence of depression in this population. For example, St. John and Keleher (2007) report that the elderly frequently experience social isolation and exclusion in ways that contributes to a higher incidence of depression. Likewise, Williamson (2008) notes that, "Depression in the elderly can cause a great deal of needless anguish and suffering for the family and patient. For the typical elderly patient, the symptoms described to physicians on regular visits are usually physical rather than mental" (p. 19). The elderly are frequently unwilling or unable to share their feelings concerning sadness, hopelessness, loss of interest in normally pleasurable activities, or extremely prolonged grief following a personal loss (Williamson, 2008). According to Gudmundsson and his associates (2007), many elderly suffer from depression, with the prevalence for any type of depressive disorder among this segment of the population being estimated at between 10%-15%. Elderly women are more likely to experience depression than their male counterparts, and women aged 70-74 years in the Gudmondsson et al. study were found to have a lifetime prevalence rate of 43.3%. The precise cause of this higher prevalence rate of depression among elderly women remains unclear; however, it is believed that among the elderly, depression is attributable in some part to associated organic changes and vascular disease in the brain (Godmundsson et al., 2007). In this regard, Gudmundsson et al. note that, "The occurrence of atrophy and cerebrovascular disease, such as white matter changes evidenced using brain imaging, is linked to depression in the elderly. In addition, low levels of serotonin and estrogen are associated with lower mood and are involved in brain metabolism" (2007, p. 833).

According to Takami, Okamoto, Yamashita, Okada and Yamawaki (2007), in elderly patients who have a history of depression, there is an elevated risk of relapse compared to younger patients. These authorities emphasize that, "Evidence from several studies suggests that elderly patients with a history of multiple episodes of depression are at high risk of recurrence, and that prior depression appears to be an important risk factor for depression in the elderly" (Takami et al., 2007, p. 594). Unfortunately, the elderly are also more difficult to treat for depression than younger people, particularly elderly who have a history of one or more previous depressive episodes in their lives (Takami et al., 2007). While there may be several factors involved in this, it is believed that the treatment responses and neuropsychological functions of the elderly may be impaired following several depressive episodes compared to individuals who have only suffered from an isolated episode of depression (Takami et al., 2007). According to Takami and his associates, "These findings suggest that the presence of prior depressive episodes in elderly patients might affect their neuropsychological function and treatment response" (Takami et al., 2007, p. 594).

The studies of functional neuroimaging conducted to date among the depressed elderly have indicated diminished global and regional cerebral perfusion and glucose metabolism, especially in the anterior cingulate cortex and prefrontal cortex; the findings to date, though, concerning the long-term effects of these conditions on the prevalence of depression among the elderly have been mixed (Takami et al., 2007). In this regard, Takami and his colleagues conclude that, "Although clinically the presence of a prior depressive episode appears to play a role in relapse and recurrence in elderly depression, the pathophysiological mechanisms involved are unclear" (Takami et al., 2007, p. 594).

According to Kyomen, Hennen, Whitfield, Renshaw, Gottlieb and Gorman (2007), depression is also highly prevalent among elderly patients with dementia, a combination of disorders that creates further exacerbates patient and caregiver morbidity. This issue was the focus of a study by Steffens, Potter, McQuoid, MacFall, Payne, Burke, Plassman and Welsh-Bohmer (2007) who identified an incidence of dementia among depressed elderly that was fully 300% higher than that reported among control counterparts after 5 years. According to these authorities, "The presence of mild cognitive impairment among older depressed subjects may persist after depression has remitted, and such impairment has been shown to confer an especially high risk for later dementia" (Steffens et al., 2007, p. 840). Similar findings are reported by Bhalla, Butters, Becker, Houck, Snitz, Lopez, Aizenstein, Raina, Dekosky and Reynolds (2009) who recently observed, "Late-life depression (LLD) may be associated with persistent cognitive impairment in some individuals after effective treatment of depressive symptoms" (p. 308).

There is some evidence...

This is yet another area that is cited by numerous authorities as requiring additional research. In this regard, Bhalla and her associates conclude that, "It is not clear whether depression represents a risk factor for or occurs in the prodromal stage of dementia. Thus, the nature of the relationship between depression and persistent cognitive impairment after resolution remains unclear and warrants further investigation" (2009, p. 309).
While the elderly living at home are at risk of developing depression, their counterparts who reside in long-term care facilities are at an even greater risk. In this regard, Anstey, Von Sanden, Sargent-Cox and Luszcz (2007) report that, "Community studies estimating the prevalence of depression in the elderly have found lower rates in community samples compared with the high rates reported in studies of institutionalized adults" (p. 497). Despite this higher prevalence rate for depression among the elderly in institutional settings, additional research is needed to clarify its magnitude and type. According to Astey and her colleagues, this research is important for a number of reasons, but it is complicated by the conventional approaches used to assess and diagnose depression among the elderly. As Astey et al. emphasize, "Exclusion of institutionalized adults from epidemiologic studies leads to difficulty in obtaining accurate figures for prevalence of depression in the population. Different measurement instruments make comparisons between studies difficult, and measurement instruments may not be valid in different settings" (p. 498). Similarly, in a study by Bonin-Guillaume, Jouve, Sautel, Fakra and Blin (2008), the authors report that, "Studies on elderly medical inpatients have found depression-prevalence rates as high as 35%. But only a few patients fulfill Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) diagnosis criteria for Major Depressive Disorders (MDD)" (p. 331). Likewise, McDonald (2009) emphasizes that in spite of the growing amount of research being devoted to depression, there remains a dearth of timely and relevant studies concerning depression among the elderly and how best to treat it. According to McDonald, "Most researchers and clinicians agree that the primary reason for this failure is a lack of recognition of depression in the elderly. Nowhere is this more apparent than the data from primary care practices, where approximately 5%-10% of elderly patients suffer from significant depressive symptoms and only a minority receive adequate pharmacotherapy" (p. 537). This point is also made by Benek-Higgins, McReynolds, Hogan and Savickas (2008) who emphasize that, "It is estimated that half of the 35 million people in the United Slates who are over the age of 65 are in need of mental health services, though fewer than 20% are actually being treated" (p. 283).

Comorbid mental and physical issues can complicate assessment and diagnosis of depression in the elderly because their symptoms of depression are frequently obscured by a wide range of physical problems (Benek-Higgins et al., 2008). Furthermore, a majority of elderly who suffer from depression fail to receive treatment based on a longstanding misperception that depression is simply part of the normal aging process and that the elderly are unable to benefit from psychotherapy (Benek-Higgins et al., 2008). The diminished cognitive abilities of many elderly depression sufferers, though, may also adversely affect their ability to benefit from psychotherapeutic interventions that could be effective with younger patients (McDonald, 2009).

Consequently, many elderly patients in both home care and long-term care facilities who may have depression remain undiagnosed and untreated for the condition, reinforcing the need for clinically useful and validated assessment and diagnostic instruments that can be used to identify depression among the elderly (Bonin-Guillaume et al., 2008). Although careful assessment of elderly patients for depression is an important step in determining the extent and nature of a depressive condition, there also remains a paucity of relevant and timely information concerning the validity of standardized screens such as the 15-item Geriatric Depression Scale (GDS) with regards to the diagnostic assessment in these populations (Marc, Raue & Bruce, 2008). To fill this gap, Marc and her associates (2008) evaluated the effectiveness of the GDS and found the instrument to be reliable and clinically useful. Based on these findings, Marc et al. concluded that:

1. The very old can be screened appropriately despite clinician beliefs that this population is too difficult to assess;

2. The presence of a major depressive episode among elderly…