Study explores how to prevent cognitive decline in people with dementia

Worldwide, around 55 million people have dementia, with over 60% living in low- and middle-income countries. Some good ways to prevent Alzheimer's disease and dementia are physical activity, nutrition and cognitively stimulating activities. 

An international team of researchers led by Universite de Montreal psychology professor Sylvie Belleville determined how many of those intervention sessions were needed to prevent cognitive decline in people at risk. It was only about a dozen. 

The study was published in 'Alzheimer's & Dementia: The Journal of the Alzheimer's Association. The study by Dr Belleville and colleagues at the universities of Toulouse and Helsinki showed that 12 to 14 sessions were all that's were needed to observe an improvement in cognition. Until now, the number of sessions or "doses" needed for optimal effect had been unknown.

"In pharmacological studies, every effort is made to define an optimal treatment dose needed to observe the expected effects, " said Belleville, a neuropsychologist and researcher at the research centre of the UdeM-affiliated Institut Universitaire de geriatrie de Montreal.

"This is rarely done in non-pharmacological studies, especially those on the prevention of cognitive decline, where little information is available to identify this dose," he added. "Defining an optimal number of treatment sessions is therefore crucial.," she continued.

"Indeed, proposing too few sessions will produce no noticeable improvement effects, but too many sessions are also undesirable as these interventions are costly. They are costly both for the individual who follow the treatments, in terms of time and involvement and for the organization offering these treatments."

The study was based on a secondary analysis of data from the three-year Multidomain Alzheimer Preventive Trial (MAPT) and looked at 749 participants who received a range of interventions aimed at preventing cognitive decline. These included dietary advice, physical activity and cognitive stimulation to improve or maintain physical and cognitive abilities. 

In their research, Belleville's team noted that people's individuality should be considered while determining the optimal treatment dose. In their study, the researchers evaluated the effects of the sessions in terms of each participant's age, gender, education level, and cognitive and physical condition.

The relationship between the "dose" each received and their cognitive improvement was then analyzed. The main results showed an increase with dose followed by a plateau effect after 12 to 14 sessions.

In other words, one needed enough dose to see an effect but offering more than 12 to 14 sessions of treatment did not mean better results. That said, participants with lower levels of education or more risk factors for frailty had benefitted from more sessions.

The conclusion was that it was important to identify and target an optimal dose and to customize the treatment for each individual, the researchers said. Not only was "dosage" an important component of behavioural interventions, but it could also provide valuable information when time and money were limited, helping public-health agencies develop effective prevention programs and offer guidance to older adults and clinicians.