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Why dementia’s imitators must be unmasked

Several illnesses related to nutrition can have effects similar to dementia; know the signs of each.
By Ngaire Hobbins

I’m a dietitian. My work naturally looks mostly at the part food plays in people’s lives. But while food and nutrition are undeniably vital in maintaining health, when it comes to issues around cognitive decline in ageing, they represent just one possible contributing factor. So dietitians working with older people look at much more than just the food people eat when determining how to best support health and quality of life.

Dementia and the cognitive issues that can precede its diagnosis affect eating, usually causing weight loss and resulting morbidity and mortality. But there are some things that can masquerade as dementia and its important these are considered when cognitive issues arise, because depression, dehydration, delirium or a deficiency of Vitamin B12, – all of which cause similar neurological symptoms to dementia – can all be cured, while dementia unfortunately can’t be.

What can happen is that people avoid seeing a doctor, fearing a diagnosis of dementia when they, in fact, have treatable conditions. That sort of delay in seeking help can end up causing permanent

damage that is otherwise preventable. Here are some key factors when diagnosing these conditions.


Depression in an older person can cause apathy, unresponsiveness and an apparent inability to communicate, so it can easily look like dementia. It can also be a part of dementia, but it’s important

to seek professional assessment because treatment can put the person back on track if depression is the overriding cause of the symptoms. And if it is dementia instead, nothing has been lost in checking. From a nutritional point of view, depression causes lack of interest in food and reduced intake, further complicating an individual’s health and potentially their cognition by contributing to malnutrition and



Delirium is a serious, life-threatening medical condition that can occur in older people as a result of infection, fever or dehydration, or following a general anaesthetic. It is more likely to occur if people take certain medications or more than three different types of medicine.

Symptoms such as confusion, agitation, disorientation, incoherent speech, unusual apathy, hallucinations and extremes of emotion can make diagnosis unclear at times. Delirium might look just like dementia to the casual observer – it’s easy to suspect it as the culprit when there’s no obvious illness or fever – but there is an important clue to diagnosing it: delirium usually comes on quickly and the symptoms can come and go, even with a day or so in between at times, though they are usually more pronounced at night.

Dementia, in contrast, usually develops gradually over weeks, months or years and, once evident, symptoms tend to be constant.

In older people, especially anyone taking medication for chronic pain, the pain or fever of underlying infections can be masked. Undiagnosed respiratory, oral and urinary tract infections commonly

contribute to delirium. And unfortunately, advancing age and previous bouts of

delirium increase its likelihood of occurring during illness.

One important consideration with delirium is the effect of reduced clearance for medicines due to age and weight loss – loss of muscle especially. For example, weight loss frequently precedes a diagnosis of dementia, so unless medications are adjusted for the lower body weight, even drugs that have caused no problems in the past can generate side effects that muddy the waters in dementia/delirium diagnosis.

Assessing the possible effects of medications is the role of pharmacist and doctor and I always advise clients to seek advice if they have concerns, but

being aware of the effect of weight loss, minimising its impact and attempting to turn it around where possible are as

essential in cognitive health as in physical wellbeing.


Dehydration is well known to impair cognition at all ages and is common in older people for myriad factors that cause

either reduced fluid intake, increased losses, or a combination of both. Contributors include altered levels of various hormones, age-related reduction in kidney function, reduced levels of body muscle (causing overall body fluid level

reductions), gastrointestinal problems, the impact of diuretics and other medications, blood loss due to accident or surgery, frequent poor food and fluid intake and the underappreciated effect of people intentionally drinking less to reduce output when they’re incontinent.

Not only does dehydration affect cognition – particularly attention and wakefulness, memory and speed of processing thought – but also it makes delirium more likely in even mild illness, especially in later age.

When it comes to fluid intake for older people, there are two main groups to consider: those who can eat well and

haven’t lost weight, and those who struggle to eat well and have lost weight. For the former, advising a drink of water with each meal and extra during hot weather and activity, whether they feel thirsty or not, is mostly adequate.

But for those who are eating inadequately or who have lost weight, encouraging water intake can be unhelpful because any drink can contribute to feelings of ‘fullness’ so that they don’t eat enough kilojoules or protein or other nutrients.

For these people, dietitians can devise a plan incorporating a range of drinks and foods that supply fluid and nutrients at the same time.

Vitamin B12 deficiency

While a B12 deficiency usually causes peripheral neurological symptoms such as numbness and tingling in the hands, feet, arms and legs, these are not always apparent and it’s the additional confusion, disorientation and changed behaviour that often suggests dementia. But B12 deficiency is easily detected with a simple blood test and then is completely reversible, whereas delaying treatment can cause permanent damage to the brain and nervous system.

Vitamin B12 is only needed in very small quantities but a number of things can reduce the amount the body absorbs from food.

For example, sometimes as people age they reduce their intake of meats and other animal foods. For most, however, changes in absorption probably have the greatest impact – adding up over the decades. B12 relies on a certain level of stomach acid to assist its absorption from food.

Over the years, these stomach acid levels tend to decline. Also, many people take anti-reflux medications to reduce stomach acid and gastrointestinal upsets can increase, pushing food through the gut too fast to make the most of the nutrients it contains.

There is no need to stop giving required medications, but what is important is ensuring B12 levels are checked regularly

so treatment can commence. If there are any signs of altered cognition, check to make sure a deficiency is not the reason for the problem.

If these possible contributors have been ruled out and a dementia diagnosis is made, it is essential to realise that most

people continue enjoying many years with their families and friends. Seeking the advice of an accredited practising dietitian as soon as possible is important: unless weight loss is minimised and food/fluid intake is adequate, there is a high risk of malnutrition and dehydration, triggering physical and mental frailty that will hamper quality of life in the precious years ahead.

Ngaire Hobbins is a dietitian specialising in geriatrics, dementia and ageing wellness, and author of Eat To Cheat Ageing. See: eattocheatageing.com.au

Contact an accredited practising dietitian at daa.asn.au

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