Pills containing an extract of marijuana do not significantly ease some of dementia's most difficult symptoms, including agitation, aggression and nighttime wandering, says the largest-ever study testing the safety and effectiveness of tetrahydrocannabinol (THC) on elderly dementia patients.
The new research did, however, offer some hope that marijuana might help this most vulnerable patient population: At the low doses tested, THC caused few notable side effects, suggesting that trials testing such medication at higher doses for dementia symptoms could safely move forward.
In a group of 50 patients diagnosed with Alzheimer's disease, dementia caused by strokes, or mixed dementia, 24 got three daily 4.5-mg THC pills, at 9 a.m., 2 p.m. and 8 p.m., and the rest received three placebo pills daily.
Both groups of patients suffered from the behavioral disturbances that make caring for dementia patients--in and out of institutional settings--difficult and sometime dangerous. For at least a month before they were enrolled in the trial, subjects were often agitated, were moderately aggressive and wandered sleeplessly at night.
But at the doses of THC tested, those symptoms did not improve any more in the trial's active arm than they did among patients who got a placebo.
The study's authors noted that, among those getting the marijuana treatment, none reported feeling "high," and caregivers and research staff saw no behavior changes that suggested that the pills' psychoactive properties affected them. The side effects that most concerned researchers--dizziness, falls and sleepiness--were no more common in those given the THC pills than in those taking placebo.
While researchers were heartened by THC's lack of troublesome side effects, that observation, in fact, suggested they may not have gone far enough.
"The observation that there was no biological signal of adverse events suggests that the dosage is too low, as a psychoactive drug is rarely effective without showing any side effects."
The new research, conducted in the Netherlands and published in the journal Neurology on Wednesday, may prompt new efforts to test marijuana as a means of easing dementia's difficult neuropsychiatric symptoms. Few other medications have proven very effective at doing so without side effects that are problematic: Some antidepressants and antipsychotic medications are widely used, but come with an increased risk of heart attacks, strokes and death.