The Cognitive Health Guide

Normal ageing versus something more

Cognition changes across adult life, and not all of it is decline. Processing speed and the ability to hold several things in mind at once tend to slow gradually from midlife. Vocabulary, accumulated knowledge, and many judgement-related abilities hold up well or continue improving.

The distinction that matters clinically is between changes that are common and those that interfere with function.

• Common with age — occasionally forgetting a name and recalling it later, misplacing objects sometimes, needing longer to learn something new, being more distractible.
• Worth assessing — getting lost in familiar places, difficulty with familiar tasks such as cooking a known recipe or managing money, repeating questions within one conversation, notable word-finding difficulty, personality or judgement changes, and changes that other people notice.

Mild cognitive impairment describes measurable change greater than expected for age that does not yet substantially interfere with independence. It sometimes progresses, sometimes remains stable, and sometimes improves — particularly when a reversible contributor is found.

Reversible contributors worth ruling out

One of the strongest arguments for being assessed rather than assuming the worst is that several contributors to cognitive change are treatable.

• Depression — can impair concentration and memory substantially, sometimes closely resembling early dementia.
• Thyroid dysfunction — affects processing speed and mood.
• Vitamin B12 deficiency — more common with age, some medications, and restricted diets.
• Medication effects — several categories affect cognition, particularly in combination and in older adults. A medication review is often the highest-yield step.
• Obstructive sleep apnea — associated with impaired attention and memory that often improves with treatment.
• Alcohol — both intoxication and long-term heavy use affect cognition.
• Hearing and vision loss — reduced input can look like cognitive impairment on testing and in daily life.
• Delirium — an acute confusional state from infection, dehydration, or medication, which needs urgent attention.

What supports cognition day to day

The evidence-supported list overlaps almost entirely with general health advice, which is a reflection of how tightly brain and body health are connected.

• Control vascular risk — blood pressure has the strongest supporting evidence, alongside blood sugar, lipids, and not smoking.
• Move regularly — activity improves mood, sleep, and vascular health, and is associated with better cognitive outcomes.
• Sleep 7 to 9 hours consistently, and address snoring and daytime sleepiness.
• Correct hearing loss — one of the more consistently identified modifiable risks.
• Stay socially engaged — isolation is associated with faster cognitive decline.
• Treat depression and anxiety — both affect cognition directly.
• Eat a plant-forward pattern — Mediterranean-style diets are associated with better cognitive outcomes, though trial evidence for prevention specifically is more limited.
• Protect your head — helmets and fall prevention reduce traumatic brain injury, a recognised risk factor.

Brain training, supplements, and tests

Brain-training products reliably improve performance on the specific tasks they train. Evidence that this transfers to everyday memory or real-world function is weak, and regulatory bodies have acted against companies making unsupported claims. Learning something genuinely new and demanding — an instrument, a language, a complex skill — has better theoretical support, partly because it is difficult and partly because it is often social.

Supplements marketed for memory have not been shown to prevent cognitive decline. Treating a documented deficiency such as B12 is a different matter and should follow testing.

Direct-to-consumer cognitive tests and biological age panels are not validated for individual decision-making. Formal cognitive assessment by a clinician uses validated instruments interpreted alongside history, examination, and often input from someone who knows you well.

Getting assessed and what to expect

If you or someone close to you has noticed a change, assessment is worthwhile — both to find treatable causes and because earlier identification allows better planning and access to support.

• Start with a primary care clinician; they can begin the workup and refer if needed.
• Bring someone who knows you well; their observations are part of the assessment.
• Bring a complete medication and supplement list.
• Note when changes started, whether they are progressing, and what specifically is harder.
• Expect history taking, cognitive testing, blood tests to look for reversible causes, and sometimes imaging.
• Ask what the plan is if the first assessment is inconclusive, and when to be reassessed.

Seek urgent care for sudden confusion, which can indicate delirium, stroke, or another acute problem, and for stroke signs — face drooping, arm weakness, speech difficulty.