Table 1 Specific review questions formulated by members of the lay stakeholders, and the evidence found to address these questions

Type of dementia

For people with different types of dementia (Alzheimer’s, vascular, dementia with Lewy bodies, other types or mixed types), what interventions can help to maintain or improve food intake or nutritional status and fluid intake or hydration status?

Less than half of studies indicated type of dementia of participants, but most that did enrolled people with AD. Results of 8 ONS studies including AD patients were not consistent - some studies reported improvement in nutritional status or intake, others no effect. Studies of other interventions were too few to compare or inform conclusions.

Stage of dementia

What interventions can help to maintain or improve food intake or nutritional status and fluid intake or hydration status in people with mild cognitive impairment, mild/moderate/severe dementia?

Less than half of the studies had any data on stage of dementia of participants. Potential interventions are shown in Table 4, but in studies of people with mild, moderate and/or severe dementia oral nutritional supplements (ONS) improved one or more markers of nutritional status (though usually not all markers, and only over short periods of time). Three studies of fruit juice supplements in people with mild cognitive impairment showed little effect. Shared mealtimes with staff and a commercial lyophilised food also appeared to improve some markers of nutritional status in people with severe dementia, while social interventions (supporting social interactions around food and drink) appeared to improve measures of participation, interactions, happiness, autonomy and involvement in people with mild, moderate and severe dementia.

Setting

1. For people with dementia living in residential care or residing in a medical setting, what interventions can help to maintain or improve food intake or nutritional status and fluid intake or hydration status?

2. For people with dementia living in their own homes with or without a carer (full-time or occasional; close relative or paid carer), what interventions can help to maintain or improve food intake or nutritional status and fluid intake or hydration status?

Most of the studies were conducted in various residential or nursing settings, and very few in participants own homes. Generally, effectiveness of interventions related to the effectiveness of interventions in residential settings.

Emotional and social issues

For people with dementia, does emotional closeness of the carer (e.g. close relative vs paid carer) affect the outcomes?

Emotional closeness to the carer was not ever reported in studies, and carers generally appeared to be professional rather than family carers.

Meaningful Activity

1. For people with dementia, what interventions aimed at improving or maintaining food and/or fluid intake, nutrition or hydration status, support meaningful activity (activity around food or drink that is personally fulfilling, that people enjoy, look forward to or find important)?

2. For people with dementia, are there any interventions that decrease food or fluid intake, diminish enjoyment or quality of life, or diminish meaningful activity or social inclusion?

Few studies measured quality of life or happiness using a validated scale. However, some studies especially those with a strong social element (see main review) reported improved autonomy, involvement and interest of participants. Few interventions reported diminished intake or any poorer outcomes, except for a study that gave supplemental yogurt at breakfast, which resulted in reduced weight (possibly as the result of replacing rather than supplementing usual food)

Individualised interventions

Do individualised interventions appear more effective than those that are not individualised, in helping people with dementia to maintain or improve food and/or drink intake, nutrition or hydration status (or related outcomes)?

Studies of ONS did not offer individualised interventions (based on needs and preferences of participants) beyond a choice of flavours, but the one study of individualised snacks did not suggest they were helpful. Multicomponent individualised interventions were more positive, suggesting useful effects on some nutritional outcomes. Individualised dysphagia diet and a multicomponent food modification diet appeared to improve weight, and individualised eating assistance was not clearly helpful.

Interventions around swallowing and oral hygiene

1. Do interventions to assess swallowing (and where necessary treat swallowing problems) have any effect on food or drink intake, nutrition or hydration status (or related outcomes)?

2. Do interventions to improve oral hygiene have any effect on food or drink intake, nutrition or hydration status (or related outcomes)?

Studies assessing interventions for swallowing problems were generally inconclusive except that individual and multicomponent interventions including food modification appeared helpful in supporting nutritional status in several studies. No interventions aimed to improve oral hygiene.

Interventions in acute illness

Are there any interventions that are particularly effective in helping people with dementia to maintain or improve food and/or drink intake, nutrition or hydration status (or related outcomes) during periods of acute illness?

Only one study included people with acute illness. It provided ONS during acute illness and reported no change in nutritional status [52].