Mild cognitive impairment sat at the center of this trial. The National Institute on Aging explains that MCI means memory or thinking problems are greater than expected for age, while daily independence is largely preserved. In this 12-week randomized study, 46 community-dwelling adults age 65 or older were assigned either to water-based exercise alone or to the same pool workout paired with simple in-pool brain tasks. Both groups improved on a common cognitive screening test after training, yet the added brain work did not produce a significant extra gain over exercise alone.
The paper, published in Life on July 28, 2025, tracked cognition, cardiovascular fitness and arterial stiffness in older adults with MCI. Each group exercised in water for 60 minutes per session, three days a week, at a moderate intensity for 12 weeks. The combined group performed recall tasks involving numbers and colors during the same aerobic routine.
The headline result is encouraging and restrained at the same time. Scores on the Montreal Cognitive Assessment, or MoCA, rose in both groups and the 2-minute step test also improved in both groups. Even so, the differences between the exercise-only arm and the exercise-plus-brain-task arm did not reach statistical significance for cognition or fitness and neither group showed a significant reduction in brachial pulse wave velocity, the study’s marker of arterial stiffness.
What the trial actually found
The researchers split the 46 participants evenly, with 23 in each arm of this single-blind randomized controlled trial. By the end of the program, five people had dropped out of the water-exercise group and four had dropped out of the combined group because of health problems or inconvenience. That left completion rates of 78.26 percent and 82.61 percent, a respectable level of adherence for a three-times-weekly program in older adults.
After 12 weeks, average MoCA scores rose from 21.70 to 25.48 in the water-only group and from 22.48 to 26.57 in the combined group. Those changes worked out to gains of 3.78 points and 4.09 points and both within-group improvements were statistically significant. The combined arm finished slightly higher, but the between-group comparison was not significant, which means the study did not show a reliable added cognitive benefit from the extra brain tasks.
Fitness followed the same pattern. On the 2-minute step test, the water-only group improved by 22.87 steps and the combined group improved by 18.39 steps. Both groups moved upward, yet the gap between them was trivial in statistical terms. The extra cognitive layer did not create a measurable performance edge.
The authors also reported that 14 participants in the water-only group and 17 in the combined group scored at or above the paper’s screening cutoff for normal cognition after treatment. That detail is worth handling carefully. A better screening score can be good news, but it does not prove that MCI was cured or that disease processes were reversed. It shows that many participants crossed a threshold on a short cognitive assessment after the program.
What participants did in the pool
Every participant followed a moderate aquatic exercise routine monitored by heart rate, with intensity set at 50 to 70 percent of estimated maximum heart rate. The American Heart Association describes target exercise heart rate as a practical way to stay within a planned training zone. Sessions included a 10-minute warm-up, a 40-minute aerobic phase and a 10-minute cool-down. The movement list was broad enough to keep the class active, with knee lifts, squats, arm motions, stepping patterns and trunk work performed against the resistance of water.
The combined arm did not receive a separate desk-based memory course before or after the workout. Instead, the added cognitive training happened during the pool session itself. Participants carried out recall tasks involving numbers and colors while they exercised, creating a dual-task format in which physical movement and mental effort were layered together in the same 40-minute block.
That design matters because it keeps the comparison clean. Both groups received the same exercise dose, the same session length and the same 12-week schedule. The main difference was whether simple recall tasks were added during the aerobic work. When no significant between-group advantage appears under those conditions, the most defensible summary is straightforward: the water exercise helped, but the added brain tasks did not clearly help more.
Why both groups may have improved
The study team, based primarily at Thammasat University, points to a familiar explanation. Moderate aerobic exercise can increase blood flow, oxygen delivery and nutrient supply to the brain while also supporting broader vascular and neural adaptation. Their discussion links these effects to processes such as neurogenesis, angiogenesis, synaptic plasticity and higher levels of neurotrophic factors that are often discussed in exercise-and-brain research.
Water adds its own practical advantages for older adults. Buoyancy reduces joint loading and water resistance gives people a way to work against force without the impact of land exercise. For participants in their late 60s who may have pain, weakness, or balance concerns, that can make regular aerobic work more tolerable. A program that people can actually complete often has more clinical value than a harder program that they abandon early.
The trial’s results fit that logic. MoCA scores improved in both groups and so did cardiovascular fitness. If the core active ingredient was the moderate-intensity aerobic exercise itself, then a shared gain across both groups is exactly what you would expect. The data support that interpretation more strongly than they support any special advantage from the in-pool recall exercises.
The study also fits with broader guidance that treats exercise as a reasonable non-drug strategy for people with MCI. The American Academy of Neurology guideline has recommended regular exercise for cognitive symptomatic benefit in mild cognitive impairment. This Thai pool study does not rewrite that landscape, but it does add another example suggesting that structured physical activity may help cognition and functional fitness in this population.
Why the brain tasks did not pull ahead
The simplest explanation is statistical: the added tasks did not produce a big enough extra effect for this sample size. With 23 participants per arm at the start and nine total dropouts by the end, the study was always going to be modest in power. A small real advantage from dual-task work could have been missed, especially if ordinary variation in baseline cognition, education, health, or motivation blurred the signal.
The tasks themselves were also fairly simple. The paper describes them as recalling numbers and colors during the water workout. That may add some mental load, yet it is a narrow form of brain challenge compared with broader multi-domain cognitive training programs that work across memory, attention, inhibition and planning with progressively harder tasks. In other words, the added mental component may have been too light to separate itself from the benefit of exercise.
There is another practical point. When physical exercise already improves cognition in both groups, the ceiling for an extra short-term gain can shrink. The combined group did score slightly higher after treatment, but the study’s own analysis says that difference was not significant. For readers focused on MCI, that is the key line to keep in view: the trial does not support a claim that added brain tasks gave these participants a reliably superior cognitive outcome.
The same pattern appeared in fitness. Dual-tasking did not produce a better 2-minute step test result than exercise alone. So the null added-benefit finding was not limited to one outcome. It stretched across the study’s two most practical gains, cognition and cardiovascular fitness.
Why arterial stiffness barely moved
The third outcome was brachial pulse wave velocity, used here as an estimate of arterial stiffness. Baseline values were 1523.91 cm/s in the water group and 1653.00 cm/s in the combined group. After 12 weeks they were 1531.09 cm/s and 1695.61 cm/s. Neither the within-group changes nor the between-group differences reached significance.
The authors offer a few reasons. First, the program was moderate, not vigorous and lasted 12 weeks. Their discussion notes that stronger exercise intensities or longer interventions have shown clearer effects on pulse wave velocity in some earlier studies. A moderate pool routine that is enough to lift cognitive scores and stepping performance may still be too gentle, or too brief, to change this vascular measure.
Second, the group’s average pulse wave velocity was already within the range reported for older adults in previous studies. If participants were not starting from unusually stiff arteries, there may have been less room for improvement. The sample was also overwhelmingly female, more than 93 percent and sex differences can interact with vascular aging in ways that complicate simple comparisons.
For the article’s main MCI question, the arterial finding acts as a useful brake on overstatement. This was not a case where every tracked measure improved. The paper supports cautious optimism about cognition and fitness, while leaving vascular stiffness unchanged in measurable terms.
Limits before anyone says cognition was restored
Several limitations keep the paper from making bigger claims. The participants were ambulatory older adults from the community, most had only primary education and most were women. Those characteristics narrow how confidently the results can be applied to men, to people with more advanced frailty, or to patients whose cognitive decline comes from a different mix of underlying causes.
The MoCA itself also needs context. It is a valuable screening tool and the official MoCA resource explains why it is widely used in older adults. Even so, a higher MoCA score after 12 weeks is still a screening improvement, not a direct demonstration that the disease biology behind MCI has been halted or reversed. The study did not use brain imaging, biomarker tracking, or long-term dementia outcomes to support a stronger claim.
Another limit sits in the diagnosis itself. The authors did not sort participants by detailed cause of cognitive decline, such as Alzheimer’s disease, vascular cognitive impairment, vitamin B12 deficiency, or hypothyroidism. That matters because MCI is a syndrome with multiple pathways. An intervention can look helpful in a mixed group while working better for some causes than for others.
Because of those constraints, the paper is best read as evidence that a feasible pool exercise program can coincide with better cognitive screening scores and better short functional fitness in older adults with MCI. It is weaker evidence for any statement that the added brain tasks are necessary and it is much weaker evidence for any statement about preventing dementia.
What comes next for MCI exercise research
The next studies need to ask a sharper question. If water exercise alone already helps, what kind of mental training, if any, can add a meaningful extra benefit? Researchers could test more demanding cognitive tasks, longer follow-up, larger samples and cleaner subgrouping by MCI cause. They could also check whether any gain holds after the classes stop, which matters if the goal is durable support rather than a short boost on a screening test.
A stronger design could also separate short cognitive lift from deeper clinical change. Repeated MoCA testing can tell you whether participants are doing better on a widely used screen. It does not reveal whether their daily independence is changing in ways that families notice, or whether their longer-term risk of dementia is falling. Outcomes tied to daily function, longer follow-up and more precise diagnosis would make the field much more persuasive.
For now, the most accurate reading stays close to the trial’s actual numbers. Water exercise looked beneficial for older adults with MCI, the added in-pool recall tasks did not show a significant extra advantage and arterial stiffness did not improve. That is a useful result on its own, because it points clinicians and families toward a realistic possibility: simple, tolerable exercise may carry much of the benefit, even before more elaborate brain-task add-ons prove that they are worth the effort.
