Diet and dementia: Encouraging older people to eat well for brain health

• It is vital to identify risk factors and promote dietary changes at the preventive and early stages of dementia – for example, diet has a significant role in managing hypertension, which is a risk factor for dementia.
• Be aware of changes in body weight – weight loss may be a consequence of dementia, but may also cause changes that lead to or accelerate the development of dementia.
• People with dementia must be well supported and cared for to ensure they get the meals and nutrients they need, but those with end-stage dementia should not be forced to eat.

The number of people with dementia in New Zealand is projected to increase over the next 30 years from 70,000 in 2020 to 170,000 by 2050. The increasing prevalence affects all ethnic groups, with the number of Māori, Pacific peoples and Asians being diagnosed with dementia also likely to increase.¹

Dementia, traditionally thought of as a disease of ageing, typically starts to develop 20 years before symptoms manifest. Therefore, targeting those with risk factors in their 40s and 50s may help prevent up to 40 per cent of dementia diagnoses in the future.²

Diet and lifestyle make up five of the 12 modifiable risk factors outlined in the 2020 Lancet Commission report on dementia prevention, intervention and care. These include managing high blood pressure, obesity, alcohol intake, diabetes and physical inactivity.² So, essentially, what benefits the heart is also beneficial for the brain.

Modifiable risk factors

The report in The Lancet recommends maintaining systolic blood pressure at 130mmHg or lower for adults aged 40 and above. Diet has a significant and effective role in blood pressure control.

The dietary approaches to stop hypertension (DASH) diet is an intervention shown to lower blood pressure. It aims to reduce dietary sodium, total fat and cholesterol, while being high in vegetables and fruit, and encourages whole grains, fish and nuts.³ The DASH diet and the Mediterranean-style diet have shown promising results in the prevention of dementia.^4–6

The Mediterranean eating style encourages plenty of vegetables, fruits, nuts, seeds, legumes, extra virgin olive oil and olives, focusing on fresh foods with minimal processing. For those under age 70, eating more seafood, legumes and nuts as the main source of protein is advised, with one to two redmeat meals a week.

For adults over age 70, protein becomes more important and should be encouraged at every meal; the recommendation of reducing red meat is less important.

On diagnosis of dementia, nearly 50 per cent of people have lost weight in the previous year. Weight loss may be a consequence of dementia due to increases in the resting metabolic rate, which is thought to be caused by increased beta-amyloid deposition.

Additionally, weight loss itself may cause changes that lead to or accelerate the development of dementia through the loss of lean body mass (muscle loss), resulting in inflammation occurring in the brain. Either way, changes in body weight could be a key predictor of the onset of dementia.

Preventing ongoing weight loss is incredibly important to ensure no further loss of muscle occurs. Muscle loss can lead to loss of balance, impacting activities of daily living, as well as loss of appetite, increased frailty and development of sarcopenia. Maintaining weight and encouraging exercise will help to maintain muscle and reduce inflammation.

Mild to moderate cognitive decline

Dementia may lead to some adults eating more and some eating less. Those eating less are most likely still hungry but have lost the ability to shop, cook or prepare meals for themselves. Ensuring these adults are well supported and cared for is essential.

Some may do best with a supply of finger foods, such as sandwiches, cooked vegetables and meat cut into pieces, boiled eggs and sliced fruit pieces. Some may need assistance with cooking and eating. Many adults with dementia need prompting and reminding of how to eat. They often do better when around others who are eating, as visual cues may help remind them how to eat.

Most regions have support groups and day groups, and some retirement villages may offer cooked meals for day visits. Meal delivery services also operate in most towns and cities. It is worth knowing what is available in your area.

Eating small, nutrient-dense meals may be easier, such as nourishing soups, smoothies and even desserts. Nutritional supplements may be necessary to help meet calorie and nutrient requirements, although supplements already prepared are likely to be better managed than powder-based supplements. It is best to advise that supplement drinks be taken between or after meals so as not to affect the appetite at mealtimes.

There are other factors, aside from forgetting to eat, that may cause weight loss to occur:

• Taste alterations, resulting in food tasting bland. The desire for sweet foods often increases as dementia advances.
• Coordination is affected, making it difficult to use utensils or feed oneself. Often, eating can become quite messy as not all food makes it to the mouth.
• Appetite triggers can be reduced in the brain, resulting in a loss of appetite or early satiety.
• Poor-fitting dentures often occur after weight loss, making it difficult or painful to eat.
• Some medications may impact the desire to eat. This can be made worse if medications need to be crushed as they can leave an unpleasant taste in the mouth. Some medications may also cause increased sleepiness, meaning mealtimes are missed or people are too sleepy to eat the meal.
• Focusing on meals can be a challenge as people often become easily distracted and lose interest in eating, resulting in less time eating and fewer calories consumed.
• Appetite is stimulated by exercise and activity; therefore, lack of activity may decrease appetite. Encouraging movement before a meal can aid hunger and improve appetite.

Advanced dementia

Many with advanced dementia may need to live in care. At some point, loss of mobility may occur. For these adults, nutrition is still important to manage the risk of pressure injuries and reduced immunity. A focus on calorie-dense foods to maintain weight will be needed, as well as adequate protein at each meal and extra protein if pressure injuries occur.

The World Alzheimer Report 2012 found that up to half of people with dementia in care homes had inadequate food intake.⁷ Many in care may need to be fed, and feeding a resident with dementia may take longer than other residents, so adequate staffing should be in place to ensure all residents get the full care they need.

Residents may do best if there are minimal distractions. Too many items on a table or too many food choices at once can increase confusion.

Some aged residential care homes serve the main meal and dessert at the same time, which should be discouraged as it can be confusing and lead to only a small amount of the main course eaten – who wouldn’t want their dessert first if it was served at the same time?

A small study found that high-contrast, coloured plates led to 25 per cent more food being eaten. Providing contrast at mealtime appeared to help those with dementia, compared with eating food from a white plate where they were less likely to see the food.⁸

Residents who refuse meals may decide to eat the meal if given later on. Refusal of meals may be due to several factors such as poor dentition, difficulty chewing foods, difficulty swallowing, mouth or tooth infections and feeling overwhelmed.

There will come a time for many when the desire to eat has gone. Fluids may be better tolerated and more enjoyable. Providing a variety of nourishing fluids and favourite foods, whether it is ice cream for breakfast or Weet-Bix for dinner, can help to provide some comfort.

Family members can become distressed when their relative stops eating, but this is a natural consequence of end-stage dementia. Forcing someone to eat at this stage can be uncomfortable and distressing and should be discouraged.

Focusing on nutrition at the preventive and early stages of dementia is where diet is likely to have the most impact. Therefore, identifying risk factors early and promoting dietary changes is vital if we are to reduce the increasing number of dementia diagnoses.

Leigh O’Brien is a registered dietitian at Dietary Specialists private practice in Christchurch