Ageing leads to brain shrinkage, vascular changes, and cognitive decline, with increased risks of stroke, white matter lesions, and dementia. Protective factors like regular exercise, a healthy diet, and education may help mitigate these effects. Brain changes vary across regions, with the prefrontal cortex most affected and the occipital least. Cognitive functions like memory and executive function decline with age, while white matter lesions and vascular changes contribute to cognitive impairment. Neurotransmitters like dopamine and serotonin decline, and hormonal changes, particularly in women, may influence cognitive function. Vascular factors such as hypertension and diabetes are linked to dementia. Protective factors include diet, moderate alcohol intake, and cognitive engagement. Biological age may differ from chronological age, and lifestyle factors can influence brain health. Research highlights the complexity of brain ageing, with a need for further studies to understand mechanisms and develop interventions. Future research should combine cross-sectional and longitudinal studies to better understand cognitive changes in ageing.Ageing leads to brain shrinkage, vascular changes, and cognitive decline, with increased risks of stroke, white matter lesions, and dementia. Protective factors like regular exercise, a healthy diet, and education may help mitigate these effects. Brain changes vary across regions, with the prefrontal cortex most affected and the occipital least. Cognitive functions like memory and executive function decline with age, while white matter lesions and vascular changes contribute to cognitive impairment. Neurotransmitters like dopamine and serotonin decline, and hormonal changes, particularly in women, may influence cognitive function. Vascular factors such as hypertension and diabetes are linked to dementia. Protective factors include diet, moderate alcohol intake, and cognitive engagement. Biological age may differ from chronological age, and lifestyle factors can influence brain health. Research highlights the complexity of brain ageing, with a need for further studies to understand mechanisms and develop interventions. Future research should combine cross-sectional and longitudinal studies to better understand cognitive changes in ageing.