When might ‘dementia’ be reversible? When it is depression.

Dementia is a broad term that refers to deficits in cognitive functioning, such as memory, language or attention, to the extent that it significantly interferes with a person's ability to function in their usual activities. We usually think of dementia as being caused by a neurodegenerative disease such as Alzheimer’s Disease, which affects brain neurons and is both progressive and irreversible. However, a number of mental health conditions, most commonly depression, can cause cognitive impairments that mimic what is seen in what we typically think of as dementia. This phenomenon has been termed pseudodementia. Note that pseudodementia is not a diagnosis.

While there is a lot of debate about the appropriateness of the term pseudodementia, it is useful in describing and highlighting the dementia-like cognitive impairments that can be caused by depression and other mental health conditions. This is of particular importance because, unlike neurodegenerative dementias, pseudodementia is often reversible with the right treatment. 

This link between depression and dementia is particularly relevant to older adults, because major depression often manifests in older adults in a way that is more likely to appear dementia-like. This also increases the risk of the depression going unnoticed, and a misdiagnosis of neurodegenerative dementia being made. 

People with pseudodementia due to depression typically experience impairments in memory, executive functioning, and speech and language, and they generally find these declines in cognitive functioning very distressing. Their deficits may be evident as impaired:

·       word finding 

·       speed and fluency of speech 

·       memory in general

·       processing speed 

·       motor response

·       focus and concentration

·       ability to complete tasks 

·       organisation

·       decision making 

In addition, people with pseudodementia may suffer from other symptoms of depression including:

·       withdrawal from activities and social interactions

·       anxiety

·       poor sleep patterns

·       appetite/weight loss or gain

·       feelings of helplessness or hopelessness

·       low energy

Importantly, older adults are more likely to experience depression without significant sadness, and may not realise they are depressed, adding to the difficulty in diagnosis. 

Clearly even a subset of these symptoms is concerning. However, people with cognitive impairments associated with underlying depression can respond to a variety of treatments targeting the depression, such as psychological therapy and antidepressant medications, or a combination of the two. Evidence-based psychological therapy approaches that can be effective in the treatment of depression include cognitive behavioural therapy (CBT), and interpersonal therapy (IPT). CBT focuses on exploring and changing thoughts and behaviours that affect how we feel, while IPT investigates and addresses patterns in relationships with others that may negatively impact mood.

It is important to note, however, that while depression can lead to cognitive difficulties that look a lot like neurodegenerative dementia, dementia due to Alzheimer’s Disease can also involve low mood symptoms (particularly in the early stages). Therefore expert assessment and investigation of the underlying cause of any cognitive impairments is important in order to provide appropriate diagnosis and optimal treatment or management. Your GP is a good place to start if you have concerns, and documenting all the symptoms you have noticed will also be helpful.