Unfortunately, you can't always know if someone who has dementia is depressed. Dementia can make depression much trickier to diagnose, since the symptoms of depression and of dementia can overlap.
For example, anxiety, agitation, apathy, and/or irritability can be seen in either dementia or depression, or in both. It's very common for people with dementia to have depression as well.
For anyone with dementia
To be diagnosed with depression, a person should show, over at least a two-week period, evidence of at least one of these two key symptoms:
- Feeling down/depressed/hopeless
- Being unable to find enjoyment in any activities
Note that changes in routine can increase confusion and emotional responses in people with dementia. So it's best to have the person evaluated for depression when his or her routine has stabilized (not immediately after a move, for example).
For a person with mild-to-moderate dementia
Try asking these five questions, known as the short version of the Geriatric Depression Scale:
- Are you basically satisfied with your life?
- Do you often get bored?
- Do you often feel helpless?
- Do you prefer to stay at home rather than going out and doing new things?
- Do you feel pretty worthless the way you are now?
A "no" to question 1 or "yes" to questions 2 through 5 are considered depressive responses. Two out of five such responses in total suggests the diagnosis of depression.
For a person with more significant dementia
Because the person with late-stage disease is apt to have lost a lot of conversational ability, the caregiver and healthcare provider may have to rely on observing behavior and apparent mood. For example, frequent crying would signal a sad mood. No longer enjoying the company of even familiar friends and family would also be a concerning sign. The Cornell Scale for Depression in Dementia is a special questionnaire that can give added insight.
Sometimes after careful evaluation, healthcare providers may still not be sure if depression is present. This is especially common if there are other health problems that could be causing pain or tiredness. In this case, it's usually reasonable to try treatment for depression for at least several months. Lack of improvement can suggest that the concerning symptoms were not in fact due to depression.