Doc: Is pot OK for asthmatic Alzheimer’s patient?

Dear Dr. Roach: I have a friend, age 56, who was diagnosed with Alzheimer’s disease a few years ago and has been taking Aricept, which has helped immensely. Now she has begun taking medical marijuana, supposedly to help her lungs at night from asthma. She takes the Aricept at dinner, then the pot about three hours later, in a capsule. What are the contraindications on the brain of taking this marijuana with Aricept? We are really concerned about this new pot use, but she seems to think it is just fine.

N.H.

Dear N.H.: Although your friend is taking marijuana in a capsule, most people smoke it. Any lung irritant (marijuana smoking is a very powerful irritant) can worsen asthma or other lung diseases. Pot smokers are more likely to have asthma, despite a 40-year-old study that showed marijuana can make asthma better in the short term. In the long term, smoking marijuana is not a good choice for asthmatics.

I also found several studies looking at the effect of marijuana (or some of its components) in both prevention and treatment of Alzheimer’s disease, and the results are mixed.

Very low doses of THC (the most active psychoactive ingredient in marijuana) seemed to cut beta amyloid, a protein found in the brains of people with Alzheimer’s. It also cut brain inflammation. However, this is not strong evidence it can protect against developing AD, and only large-scale studies could produce a more definitive answer. It is likely there may be other effects of marijuana, especially at higher doses, that are not helpful.

In terms of treatment, one medical marijuana study showed no benefit at all, while another showed improvement in some symptoms: delusions, aggression and agitation, irritability, apathy, sleep and caregiver distress.

I could not find anything to suggest how marijuana might interact with donepezil (Aricept) or similar drugs.

Dear Dr. Roach: Your recent article regarding warfarin testing was timely for a question we have been struggling with regarding our 88-year-old mother, who is facing warfarin therapy. My brother says the lab where he goes for INR testing advised him that the testing monitors blood levels of warfarin. The lab where my mother goes states that the test monitors how long it takes the blood to clot. Could you please advise which is correct?

C.S.

Dear C.S.: Warfarin works by blocking vitamin K, absorbed from food, which in turn is necessary for the liver to make clotting factors. Warfarin effectiveness is measured by the INR (international normalized ratio), a test of blood-clotting time. Strictly speaking, your brother’s lab is correct, but the two amount to almost the same thing, since it’s the amount of warfarin (as well as the amount of vitamin K taken in) that affects the clotting times.

Email questions to ToYourGoodHealth@med.cornell.edu.