The search for a way to treat some symptoms of Alzheimer’s disease has puzzled scientists for decades. This may be why some researchers are shifting their focus slightly, investigating whether treating the systems affected by Alzheimer’s (as opposed to the causes) may be better to help them find a treatment.
It is what researchers of a new study have shown – Finding that drugs used to treat ADHD may show promise in managing symptoms of Alzheimer’s disease.
The researchers conducted a systematic review; that looks at how noradrenergic drugs (commonly used for ADHD) work in managing the symptoms of Alzheimer’s disease and found that taking these drugs improved certain brain functions and other symptoms, such as apathy, in patients with Alzheimer’s disease.
Drugs that target a noradrenergic system include the locus coeruleus, a tiny region of the brainstem. This area involves a broad array of brain functions, such as memory, attention, and learning. The primary control of this system is by neurotransmitters (a unique type of brain cell that sends and receives messages in the brain) called noradrenaline – which also plays a vital role in our body’s “fight or flight” response.
The locus coeruleus is the first recorded brain area to show pathological signs of Alzheimer’s disease; these signs manifest as tau tangles; Tau is an important protein; essential for good brain function. But, people with Alzheimer’s disease, tau proteins accumulate together.
As these tangles build up, they interfere with the noradrenergic system’s ability to keep neurons healthy. Since the noradrenergic system also helps regulate the brain’s immune system, loss of function can lead to neuro inflammation, which is another telltale sign of Alzheimer’s disease. Other mental health issues like depression, ADHD, and anxiety have also been linked to issues with the noradrenergic system’s functionality. Because of this, noradrenergic therapies may also be recommended for certain conditions. It’s interesting that people with these diseases are more likely to get Alzheimer’s.
Symptoms such as depression and anxiety often also appear before memory issues in people with Alzheimer’s disease. The presence of depression, anxiety, and other mental health issues is also associated with a higher risk of premature death in patients with Alzheimer’s.
To conduct their study, the researchers pooled 19 studies together, looking at data from more than 1,800 patients. They also looked at several noradrenergic drugs, including those used to treat ADHD and depression.
They found that in more studies, these drugs improved the overall thinking and understanding of people with Alzheimer’s disease; but failed to demonstrate any improvement in agitation, specific memory performance (such as verbal and episodic memory), executive function (the capacity to concentrate and remember instructions), or visuospatial abilities (such as drawing or buttoning a shirt).
These drugs have also been to improve apathy, which is a common symptom of Alzheimer’s. Apathy can significantly lower the quality of life and speed up the loss of brain function. Interestingly, a drug used predominantly in treating ADHD, named methylphenidate – better known as Ritalin – the drugs most commonly shown to improve apathy in Alzheimer’s patients.
Overall, study suggests that noradrenergic drugs can be beneficial for some people with Alzheimer’s disease, if the appropriate dosage is applied. However, while drawing a conclusion, care should be exercised, as this is not an experimental study – such as a randomized controlled trial, which would compare the effect of an intervention (such as a drug). In addition, there had been significantly different results in the methods and outcomes of the research examined in the review.
Despite the fact, these medications have been found to offer certain advantages for brain function. They can also have a variety of side effects; includes: heart issues, addiction, and, particularly when overused, brain alterations or psychiatric symptoms, such as hallucinations and paranoia that are similar to psychosis. Thus, it will be crucial for more research to be done to demonstrate that such medications have far more advantages than disadvantages.
When it comes to the noradrenergic drugs investigated in this study, methylphenidate (Ritalin) has recently been used short-term (six months) in a clinical trial and has shown positive results when it comes to apathy. But other drugs investigated in the study, such as the antidepressant mirtazapine, not only showed zero improvements in apathy but were associated with an increased risk of premature death.
While the study didn’t show any improvement in memory issues for people with Alzheimer’s, it has shown us that it may be time to move in a new direction when it comes to treating this disease. Instead of focusing only on potential causes (such as the amyloid and tau hypotheses), the research could now benefit from including treatments that target the systems which are involved in different symptoms of Alzheimer’s.