The cause of most dementia is unknown, but many potential factors associated with increased risk have been identified in addition to ageing, including:^1,10

• hypertension;
• diabetes/hyperglycaemia;
• excess bodyweight;
• smoking;
• long-term excess alcohol;
• physically inactivity;
• social isolation;
• depression;
• low educational attainment;
• cognitive inactivity;
• air pollution;
• poor periodontal health and tooth loss.

Sensory impairment such as hearing or sight loss may contribute to dementia, but their effects may be reversible. Phototherapy might significantly improve cognitive function in patients with dementia, potentially by compensating for the reduction in visual sensory input or by improving circadian rhythm regulation and improving brain function.^8,11

Moderate or severe traumatic brain injury (TBI), or repeated mild injuries such as concussion may be a factor several decades later in dementia developing.¹²

Among genetic components, some forms of the apolipoprotein E (APOE) gene involved in creating a protein involved in fat metabolism, are linked to increased risk of developing Alzheimer’s.¹³

Huntington's disease is a genetic disease which can impair movement, cognition and behaviour. It is due to a fault in the gene expressing a protein (huntingtin) required by neurons and for development before birth. Risk increases the more the gene is miscoded, dependent on the how the gene is inherited from each parent.¹⁴