Dear Dr Macfarlane, my questions to you are: 

1. How can we (the clinicians working in aged care) better assess mental health in older adults living with dementia? 
2. Is there connection between mental health (e.g. depression or low mood) and decline in cognition?

Thanks, Mark, for your great questions.  

Assessing mental health in older adults living with dementia requires a nuanced approach, given that the symptoms of depression or anxiety can overlap with cognitive decline. As we’ve discussed in this newsletter, rarer dementias, such as Frontotemporal Dementia are often difficult to diagnose, with symptoms often initially misdiagnosed as mental illness.  

Normally, the diagnosis of depression is dependent on a person’s ability to reliably report symptoms: to tell us how they are feeling. As dementia progresses the ability to reliably report symptoms is often lost and, instead, we become more reliant on the observations of others in order to consider the diagnosis. Certain features of depression are observable. Carers often have a clear understanding of changes in behaviour, sleep patterns, appetite and weight, and the presence of any recent social withdrawal. 

There are also depression screenings using tools specifically designed for older adults with cognitive impairment, such as the Cornell Scale for Depression in Dementia that are used. These get less helpful as cognition worsens, as they were simply not designed for those living with either severe dementia, or significant behavioural problems. 

Regarding your second question, there is a connection between depression, cognitive decline and dementia. When people are severely depressed, cognitive performance will suffer. Depression is one of the things we consider as part of the assessment of a person who is experiencing cognitive changes. 

Long-term depression causes increases in a stress hormone called cortisol. Long-term exposure to high cortisol levels can cause, among other things, shrinkage of the same parts of the brain that are affected in Alzheimer’s disease, lowering our brains’ innate resistance to the damage that Alzheimer’s might produce. 

Finally, if you look at people who experience depression for the first time at very old ages, in the absence of a clear cause such as illness of bereavement, such people tend to develop dementia at higher rates during the next five years compared to similar people who aren’t depressed. It may well be that depression, in this group, represents an early, non-cognitive symptom of dementia.