An early diagnosis can make a big difference to a person with dementia, as discussed here by the SCIE.
Between 5 and 15% of patients diagnosed with dementia will be diagnosed with depression at follow-up. Assuming just 5% of the 820,000 people diagnosed annually, over 40,000 patients may have been incorrectly diagnosed.
It can be a difficult diagnosis for clinicians to make however, as many of the symptoms overlap with those of depression in the elderly. The overlap of symptoms is extensive; poor concentration, attention, executive function and memory impairment are found in both elderly depression and dementia, amid the cognitive decline associated with normal aging. Both dementia and depression are heterogeneous in their causes, clinical manifestations and response to treatment (Benedict & Nacoste, 1990) causing the boundaries of the disorders to become blurred.
Berger et al. (1999) undertook a prospective study of depressive symptoms in 222 participants aged over 74. After three years it was found that those who developed Alzheimer’s were more likely to have motivational symptoms at baseline, such as lack of interest, loss of energy, and concentration difficulties. This association remained after adjusting for subjective memory complaints, suggesting that these symptoms were not related to self-perceived cognitive difficulties, but were part of the preclinical phase of Alzheimer’s.
Evidence that dementia causes depression stems from the inflated prevalence rates of depressive symptoms in those with dementia, another factor that can influence differentiation. Lykestos et al. (1997) report that up to 22% of Alzheimer’s patients suffer from major depressive episodes, with a further 27% suffering from minor depressive episodes.
There are a range of tests and techniques that your clinician can use to differentiate between the two disorders, which tap into slightly different types of memory and processing, differently affected by dementia and depression.
The correct, early diagnosis is important as it has a big impact on the treatment decisions and potential outcomes. If you have any questions, please don’t hesitate to call or email us and we will be happy to send you more information about dementia.