Prazosin is a medication currently approved as a therapy for high blood pressure. Research suggests that it could also be used to relieve symptoms such as aggression in moderate stage Alzheimer’s Disease (AD) patients.
AD is a neurodegenerative disorder that results in a slow decline of memory and thinking abilities as it progresses. One of the symptoms associated with the progression of the disease is an increase in agitated and aggressive behavior, which can often lead to the patient being enrolled into care homes. Currently, these symptoms are treated with antipsychotic medication, but in many cases, these can be ineffective and can have harmful side effects.
How prazosin works
During normal brain function, cells communicate using chemical messengers called neurotransmitters. Neurotransmitter levels are tightly regulated, and only certain cells can pick up these message as they can only interact with specific receptors found on the outside of these cells, like a key only fitting a particular lock.
The neurotransmitter norepinephrine (NE, or adrenaline), which is frequently disrupted in AD patients, is involved in many functions in the brain including inflammation, immune response, and memory. NE normally interacts with the alpha-1 adrenoreceptor (AR), passing the message to the cell. It is thought that an increase in the activation of AR might result in increased aggression and agitation seen in AD patients.
Prazosin is part of a class of drugs called “alpha blockers”. It competes with NE to bind to the AR resulting in a reduced activation of these receptors. This could potentially lead to a reduction in aggression in AD patients.
Prazosin in clinical trials
Prazosin is currently being tested in clinical trials and has not yet been approved by the U.S. Food and Drug Administration (FDA) for the treatment of AD patients.
The effectiveness of prazosin on moderate-stage AD has been assessed in several clinical trials. A randomized, placebo-controlled study on 24 patients (NCT00161473) took place over nine weeks in a Seattle nursing home. The patients were assessed at weeks 1, 2, 4, 6, and 8 for changes in behavior, using a number of psychiatric assessment scales. The results, published in The American Journal of Geriatric Psychiatry, suggested that prazosin significantly reduced the level of agitation and aggression in AD patients, in comparison to the placebo-treated group.
A second clinical trial (NCT01126099) has also been completed, assessing prazosin over a 12-week period compared to a placebo. The results of this trial also showed an improvement in behavior in patients treated with prazosin. The results of the two studies have been summarized in the journal,
The results of the two studies have been summarized in an article published in the scientific journal, Alzheimer’s & Dementia. A larger study, as part of the
A larger study, as part of the Alzheimer’s Disease Cooperative Study (ACDS), with 200 patients is planned but has not yet started enrolling patients.
A recent case study, published in the Journal of Clinical Gerontology and Geriatrics, showed that a single elderly male with dementia was given prazosin after all other options were tried. The patient showed a significant reduction in agitation, aggression, and physical violence following treatment, and the medication was well tolerated. The authors emphasize that current data is limited and that there is a need for further, larger clinical trials to verify these findings.
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