Descriptions of intervention(s) / exposure
Cognitive Training Intervention - The SMART Trial suite of cognitive training exercises are aimed at computer-based multimodal, multi-domain and task load-graded training in the areas of memory, executive function, attention and speed of information processing. We have chosen a subset of exercises from the COGPACK package as these were developed at a recognized neurorehabilitation centre, are based largely on well established neuropsychological tests and principles and, moreover, their effective use with psychiatric patients has been reported (McGurk et al 2005; 2007).
Training frequency was 3 days per week for the first 30 participants. It was reduced to 2 days per week for the remaining subjects as a means to reduce participant burden which was determined to be a major barrier to recruitment due to transportation difficulties in this cohort with mild cognitive impairment. Each participant in this arm will participant in two or three 45-min sessions/week (total of 52-78 sessions over 6 months). The sessions will be conducted in small groups (maximum of 10 participants), with each participant working through the memory, information processing, attention and problem solving tasks at their own pace.
Participants will complete 4 exercises per session; the mix of exercise per session is one verbal memory exercise, one visual memory exercise, and the other two rotating between attention, information speed, and executive exercises in a balanced fashion across the sessions Fourteen exercises have been chosen. Thirteen of the 14 exercises require a simple touch-screen response with no mouse operation and in this way will avoid training difficulties in the computer-naïve. Resistance Training Intervention - The progressive resistance training (PRT) will be conducted 2-3 days per week, 45 minutes per session, for 26 weeks. The subjects will be trained by experienced exercise trainers in a medically-supervised setting at a ratio of 1 trainer for 4-5 subjects.
PRT intensity was prescribed at 80% of current measured or estimated strength on each exercise using pneumatic resistance machines. This was achieved by initially measuring the 1RM twice at baseline and again after every 6 training sessions during the 6 mo intervention. The load was then set at 80% of the most recently determined 1RM, and increased by about 3% for every subsequent session as tolerated, until the next 1RM determination. Tolerance was assessed by keeping the Borg rating of perceived exertion between 15-18, adjusting the load up or down as needed to achieve this. In addition, assessor observation of pain, accessory muscle use or violations of form were used to titrate the load. For free weight exercises in which 1RM testing could not be done, the Borg scale and assessor evaluation of effort were used to monitor progression and alter loads.
We have successfully and safely used this regimen since 1988 in frail elders up to the age of 103 to induce anabolic adaptations, as well as robust physical, functional, and psychological benefits (Singh 2002). Combined Cognitive and Exercise Intervention - This group will get both the cognitive and exercise training on the same day (90 minute sessions), 2-3 sessions per week for 26 weeks. In order to take advantage of the enhanced attention and learning exhibited after an acute bout of exercise in both animal and human studies, the cognitive training will take place after the progressive resistance training. The subjects in the intervention groups will be randomised into one of the four groups: 1. Cognitive Training + Sham PRT, 2. PRT + Sham Cognitive Training, 3. Cognitive Training + PRT and 4. Sham Cognitive Training + Sham PRT.