Mental Acuity and
Mental acuity measures the sharpness of the human mind and usually considers concentration, memory and understanding, but does not measure intelligence (1). Concentration can be defined as ‘the process by which all thoughts and senses are focused totally upon a selected object or activity to the exclusion of everything else’ (2). Concentration, memory and understanding are interconnected, with the ability to concentrate being key. Take the example of memory lapses, which plague most of us at some point in our lives. For the most part, they can be explained as a consequence of poor concentration. Why? Because if your concentration is poor, then you won’t notice and retain information as much as much as you would if you are concentrating well (3). It then stands to reason that poor concentration could also impair your ability to understand and carry out tasks at work. While poor concentration and associated impaired cognitive functioning usually isn’t serious, it can however have far-reaching effects; productivity can decline and impair performance, which in turn can lead to stress and mental exhaustion.
Numerous factors influence how well we perform mentally at work. Firstly, motivation to succeed in the task is clearly important, and research shows that when individuals increase effort, they tend to focus more sharply on the task-at-hand (4). This underscores the fact that concentration is not a static process, but one that changes over time, and maintaining the intensity and focus of concentration requires effort.
Secondly, emotions can influence our performance through their effects on concentration (5). For example, let’s look at anxiety and excitement. Anxiety is characterised by feelings of nervousness and tension, coupled with negative thoughts about performance. On the other hand, excitement is characterised by feelings of adrenaline and liveliness, coupled with optimistic thoughts on performance success. However, both excitement and anxiety affect concentration in a similar way (6). Namely, as emotions intensify, concentration tends to narrow. How does this affect performance? Initially, increased emotions such as anxiety and excitement can be helpful for concentration because high arousal narrows attention, making it easier to ignore irrelevant cues so that performance improves accordingly. However, as emotions intensify, both relevant and irrelevant cues are ignored and performance begins to deteriorate (7).
Thirdly, research has shown that regular physical exercise improves cognitive functions throughout all life stages (8). In particular, executive functions, which are involved in solving problems as well as learning processes, can be positively influenced. Executive functions refer to brain functions that activate, organise, integrate and manage other functions which are important for judgment, planning, decision-making, structuring and realising tasks, and for recognising and correcting errors (9-11). An additional element of executive functioning is cognitive flexibility, the ability to think and react in a flexible way (12). It is thought that physical activity may boost these executive functions by increasing brain levels of neurotransmitters (chemical messengers that relay signals between nerve cells) such as dopamine and serotonin (13), which are important for learning, memory and executive functioning (14,15).
So, what type of exercise could benefit cognitive performance? Research has shown that increased frequency of aerobic activity (3-4 days/week compared to 5-7 days/week) is associated with enhanced cognitive performance, including cognitive flexibility, mental speed and attention, all measures of executive function (16). It appears however, that cardiovascular exercise has facilitative effects on cognitive performance only until endurance is depleted (17); Heckler & Croce (1992) found that the speed of problem solving was significantly faster after both 20-minute and 40-minute exercise sessions among fit female adults ages 27 to 49 years, whereas speed of problem solving was significantly faster only after the 20-minute exercise session for the less-fit group.
Fourthly, insufficient sleep, inadequate quality of sleep or disruptions to the sleep-wake cycle (such as those that occur with shift work or travelling to a different time zone) have consequences for how we function cognitively in the daytime. Sleep deprivation leads to reduced concentration, loss of motivation, poorer memory, poorer judgement, reduced decision-making skills and reduced work efficiency, all of which impair work performance (18). Most people who don’t get enough sleep don’t recognise the toll that it takes on their cognitive and mental health. Many people think of sleep simply as a luxury — a little downtime, but sleep actually improves learning, memory, and insight (19). So how much sleep do we need? Adults need about eight hours of sleep, depending on individual factors. Also, although we tend to need less sleep as we age, we should be guided by our own state of alertness (20).
Fifthly, stress has a complex effect on cognitive functioning, particularly memory. Research has found that brief periods of stress can potentiate memory formation whereas more severe or prolonged stressors can have deleterious effects upon broad aspects of cognition (21). Some of these effects may be due to reversible changes in the structure of nerve cells within the hippocampus, a region of the brain that is central to learning and memory. Taken to the extreme, truly prolonged exposure to stress can cause irreversible loss of nerve cells in the hippocampus, and may be relevant to the cognitive deficits seen in many aged individuals (22). However, there are numerous individual differences in vulnerability to stress-induced effects. One of these aspects has been studied and it seems that chronic stress affects cognitive functioning differently in cognitively normal subjects compared to those with mild cognitive impairment; in particular, the presence of stressful life events over a period of up to 3 years was associated with accelerated cognitive decline in older adults with compromised cognition (i.e., mild cognitive impairment) but not in cognitively normal subjects (23).
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