Effect of occupational complexity on cognitive change during a multidomain lifestyle intervention: The FINGER trial

Background Life‐long mental stimulation through occupational complexity has been associated with late‐life cognition and might affect the rate of cognitive changes in randomized controlled trials (RCTs) testing preventive interventions for dementia. The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER, ClinicalTrials.gov NCT01041989) is a landmark RCT that tested a lifestyle‐based multidomain intervention in 1260 community‐dwellers aged 60‐77 years at increased risk of dementia. Participants were randomized to either a group that received general health advice, or a 2‐year multidomain intervention that incorporated dietary counselling, exercise, cognitive training, and vascular/metabolic risk monitoring. The intervention improved global cognition (primary outcome) and cognitive sub‐domains including executive function, processing speed, and memory. This study aimed to test if the cognitive benefits of the 2‐year multimodal intervention were linked to baseline levels of occupational complexity. Method Study participants : all randomized FINGER participants with at least one cognitive outcome assessment after the baseline visit (modified intention‐to treat population), available data on last held occupation, and who were retired (N: 1026). Occupational complexity was assessed through a validated rating system, identifying three domains: complexity with data; complexity with people; and substantive complexity. Cognition was assessed at baseline, 1‐year and 2‐year with the Neuropsychological Test Battery (NTB). The following cognitive outcomes were considered: global cognition, executive function, processing speed, and memory. Data analysis : Mixed‐model repeated‐measures analyses with maximum likelihood estimation were used to analyse change in cognitive scores as a function of randomization group, time, levels of occupational complexity (standardized Z‐scores), their interaction (randomization group × time × occupational complexity), age, sex, education, study site. Result Subjects with higher levels of occupational complexity with data (i.e., occupations more mentally demanding) benefitted most in terms of improvement in executive function (interaction coefficient group × time × occupational complexity: ß[SE]: .03 (.01), p= .044) and global cognition (ß[SE]: .02 (.01), p= .060). Conclusion The cognitive change in a multidomain preventive intervention can be affected by previous occupational complexity. This facet of mental stimulation should be further investigated within RCTs for cognitive impairment.