Dr Kevin McCarroll
The concept of successful or optimal ageing has become part of the lexicon of modern day geriatrics and encompasses maintaining in as far as is possible our cognitive, physical and mental health as we grow older. Despite this, cognitive function which is crucial to healthy ageing declines significantly in many older adults.
Indeed, few conditions conjure up as much fear and anxiety as dementia, though increasing research suggests that adopting a healthy lifestyle and addressing factors like high blood pressure and cholesterol, particularly in midlife, protect against cognitive decline. Indeed, the age at which dementia is diagnosed has risen in recent years, likely reflecting better general health.
Dementia is a syndrome characterised by loss of cognitive function in two or more areas including memory, problem solving and language. While cognition and memory loss is common with advancing age, by definition dementia is said to occur only when it leads to a loss in the ability to carry out major activities of daily living.
Damage
In Ireland, about 45,000 people live with dementia and in about 80% of cases it is due to Alzheimer’s disease. Overall, dementia incidence doubles every five years from the age of 65 and by 80 it is estimated that approximately 15-20% of adults have Alzheimer’s.
In its earliest stages, Alzheimer’s leads to damage in an area of the brain called the hippocampus, a structure which lays down the trace for new memory. It is the equivalent of our brains’ ‘save button’ and when it malfunctions there is impaired ability to save new memories.
While important information may be retained early on, a progressive decline leads to the incapacity to remember most things often resulting in repetitive questioning and poor or no recognition for things that were never stored in the first place.
This may affect both visual and verbal memories but long-term memories that were stored previously remain intact. Difficulty with generating names or words can also be an early feature and reflects a language as opposed to memory problem.
For a period of up to a few years, it is possible to have memory problems due to Alzheimer’s disease without having major impacts on daily function or dementia. However, early memory problems can have several causes and the distinction is not always clear.
Mild difficulty with retrieving words or memories can often be due to poor attention due to stress, poor sleep, absent mindedness, alcohol excess, medications, stroke disease, depression and endocrine problems like an underactive thyroid.
The same conditions can impair our ability to process, pick up and encode new information as opposed to storing it and often give rise to patchy memory loss.
On the other hand, if on a consistent basis, new and particularly important information cannot be retained and there is repetition as well as a gradual decline, then it is more concerning for Alzheimer’s.
Whilst in most cases diagnosing Alzheimer’s at an early stage prior to developing dementia is not possible, memory testing can identify those at higher risk who can be followed up closely.
Currently, two medications which correct neurotransmitter imbalances in the brain are proven to help maintain cognitive function in Alzheimer’s dementia in about 30% of cases. Unfortunately, however, they have no affect on the underlying disease process.
A large amount of research has focused on using drugs to prevent the build-up of abnormal and toxic amyloid and tau proteins that occurs in the brain in Alzheimer’s. However, trials to date have not been successful or had to be stopped due to adverse effects.
Opportunity
Current research has also moved in the direction of trying to diagnose Alzheimer’s at an earlier ‘pre-dementia’ stage with sophisticated brain imaging and memory testing. This may provide an opportunity to develop treatments that slow or halt further brain damage before a disease ‘cascade’ effect may occur.
It is also now widely believed that changes in the brain predate the development of Alzheimer’s by up to decades. High blood pressure and cholesterol, diabetes, obesity, physical inactivity, smoking and depression appear to increase the risk of developing Alzheimer’s and indeed it is estimated that addressing these factors might reduce your lifetime chance by up 50%.
This has led to a renewed focus on preserving ‘brain health’ which has particularly taken stage on the back of an ageing demographic.
In short, having a healthy lifestyle and keeping physically, mentally and socially active appear important in maintaining optimal brain function and protecting against dementia.