Alzheimer’s Disease - Testing ADHD Medicine
Alzheimer’s patients may soon be
administered ADHD medication to improve their symptoms. At first glance,
this may seem odd and illogical, but the science checks out. A recent
analysis explains why and how ADHD medication works for Alzheimer’s.
One of the primary reasons why Alzheimer’s
disease (AD) is so devastating is that it affects multiply brain areas.
As more and more neurofibrillary TAU tangles (twisted protein fibers)
accumulate in brain cells, they block nutrients from reaching the cells
and ultimately cause whole clusters of neurons to die off.
This damage to the brain cells, in turn, produces the infamous symptoms
of Alzheimer’s disease, such as memory loss and cognitive decline. But
there is one more group of Alzheimer’s symptoms that gets less press -
the behavioral kind. These symptoms include depression, apathy,
agitation, and even aggression. And they can be just as severe and
disruptive to the life of the person with Alzheimer’s and their loved
ones as memory loss and cognitive decline.
A clear-cut review study published in July 2022 in the Journal of
Neurology Neurosurgery & Psychiatry shows that both cognitive and
behavioral symptoms of Alzheimer’s can be improved by treating patients
with medications used to treat attention deficit hyperactivity disorder
(ADHD).
Why can an ADHD treatment help patients with Alzheimer’s?
Let’s begin by clarifying that the types of
ADHD medication considered in the analysis are noradrenergic drugs -
medications that target a compound called noradrenaline.
And if the word “noradrenaline” rings a bell, you’re not mistaken.
Adrenaline is a hormone released by the adrenal glands located on top of
both kidneys in response to stress or low blood pressure. That is where
we get the term “adrenaline rush.” But when adrenaline travels to the
brain, it gets the name nor-adrenaline and turns into a neurotransmitter
- a brain chemical used to communicate between nerve cells.
Noradrenaline (also called norepinephrine) is made by specialized
noradrenergic nerve cells in the brain as well as the adrenal gland. As a
neurotransmitter, norepinephrine plays a huge role in cognition. It
aids us to stay focused, improves our ability to learn and memorize new
information, and helps us control inappropriate behaviors.
In Alzheimer’s disease, low noradrenaline
levels and the loss of neurons that produce norepinephrine are well
documented across many brain areas. These disruptions contribute to
symptoms often observed in Alzheimer’s disease - from loss of appetite,
depression, and sleep disturbances to restlessness, aggression,
irritability, and anxiety.
Given that we already have a selection of noradrenergic medications
available, researchers have long posited that administering such drugs
to people with Alzheimer’s may help reduce AD symptoms.
What did the research find?
The study authors examined 19 clinical trials from 1980 to 2021 that
used noradrenergic drugs (e.g.atomoxetine, guanfacine, and
methylphenidate) in people with Alzheimer’s disease and mild cognitive
impairment. These studies involved a total of 1811 participants. The
results were examined across two main kinds of symptoms:
Cognition involved memory, language, attention, and visuospatial
orientation.
Behavior and neuropsychiatric symptoms, such as depression, apathy,
and agitation.
The analysis showed that noradrenergic
drugs had a small positive effect on general cognition and a large
improvement in apathy. And the researchers conclude, “Repurposing of
established noradrenergic drugs is most likely to offer effective
treatment in Alzheimer’s disease for general cognition and apathy.”
Obviously, using existing medications to treat AD has many advantages.
For one, these drugs don’t have to be tested separately for safety and
needn’t be approved by the FDA. All the required testing and
certification have already been done in the past, which is a massive
time saver.
But it's not all rainbows and unicorns. A few more specific questions
regarding the use of noradrenergic medications for Alzheimer’s disease
are yet to be answered. For instance, we still don’t know which
particular patients would benefit from this treatment the most, as well
as the specific doses at which noradrenergic drugs should be
administered in AD.