An extensive data analysis has revealed that widely used ADHD medications may be effective at reducing the impact of Alzheimer’s disease.
The investigation examined the results of 19 clinical trials that were performed over a 30-year-period, discovering that a group of ADHD medications – known as noradrenergic drugs – potentially alleviate critical symptoms of Alzheimer’s disease.
The study’s findings are published in the Journal of Neurology Neurosurgery & Psychiatry.
What are noradrenergic drugs?
Noradrenergic drugs are a class of medications used to treat a range of conditions, including attention deficit hyperactivity disorder (ADHD), depression, and high blood pressure.
These ADHD medications target the noradrenaline neurotransmitter, also called norepinephrine, which is released by a network of specialised noradrenergic neurons that are essential for a range of arousal and cognitive processes. These include attention, learning, memory, readiness for action, and suppression of inappropriate behaviours.
Noradrenergic disruption arises in the early stages of Alzheimer’s disease, causing the cognitive and neuropsychiatric symptoms that are closely associated with the condition.
This led the team to hypothesise that targeting the noradrenergic may be an effective way to combat Alzheimer’s disease, with ADHD medications being the prime candidate.
Drug treatment for Alzheimer’s disease
For their study, the researchers analysed results from clinical trials performed between 1980 and 2021 that utilised ADHD medications such as atomoxetine, methylphenidate, and guanfacine.
These noradrenergic drugs had been used to potentially improve cognitive and neuropsychiatric symptoms in people with neurodegenerative disease. The 19 trials comprised a total of 1,811 patients, with six trials judged to be of ‘good’ quality, seven as ‘fair’ and six as ‘poor’.
The results of ten of these trials, which included 1,300 people, were pooled for global cognition, including orientation/attention, memory, verbal fluency, language, and visuospatial ability.
By measuring the results using the Mini-Mental State Exam or the Alzheimer’s Disease Assessment Scale, the team identified that the ADHD medications had an overall positive effect on cognition.
Additionally, the results of eight clinical trials that included 425 patients were pooled for behaviour and neuropsychiatric symptoms, agitation, and apathy. This revealed that the drugs had a significantly positive effect on apathy, even after eliminating outliers to account for differences in trial design and intended outcomes.
The researchers said: “Repurposing of established noradrenergic drugs is most likely to offer effective treatment in Alzheimer’s disease for general cognition and apathy. There is a strong rationale for further, targeted clinical trials of noradrenergic treatments in Alzheimer’s disease.”
Future developments
The team explained that various factors need to be evaluated before employing ADHD medications to treat Alzheimer’s disease, including appropriately targeting specific groups of patients and understanding the dose effects of individual drugs and how they interact with other treatments to avoid side effects.
