In a previous post, I wrote about how a history of depression may increase your risk of developing dementia. This connection is not well understood, and is further complicated by the fact that many Alzheimer’s patients are depressed, even when they have no previous history of depressive episodes. If my father had lived long enough, he might have been dealing with depression as well as cerebral amyloid angiopathy and probable Alzheimer’s.
“The rate of depression in people 65 and over is quite low – a few percent,” Dr. Zubenko says. “But somewhere between 30 and 50% of Alzheimer’s patients suffer from depression. Some of that is probably due to the realization that they’re losing mental capacity – major depressive episodes often seem to be triggered by stressful life events. The much higher rates of major depression in AD [Alzheimer’s disease] patients suggest that the emergence of MDD [Major Depressive Disorder] in AD is often the result of the neurodegenerative disorder.
George S. Zubenko, M.D., Ph.D.
It’s obvious that major depression increases the suffering of dementia patients and their caregivers. Dr. Zubenko points out that it also exaggerates the patients’ disabilities, makes institutionalization more likely, and may hasten death. For these reasons, it’s important to diagnose depression in dementia patients. Diagnosis can be tricky, though - doctors don’t agree on the definition of "depression" in AD, and it’s often difficult for dementia patients to communicate their symptoms.
To help diagnose and characterize depression in Alzheimer’s patients, Dr. Zubenko and his coworkers developed a diagnostic interview called Clinical Assessment for Depression in Dementia (CADD). He believes that “major depressive disorder in Alzheimer’s disease” is not the same as major depression in non-demented patients. When the CADD was administered to 243 patients with probable Alzheimer’s disease and 151 non-demented control patients, the data showed that Alzheimer’s-related depression had somewhat different symptoms than “regular” depression. In this study, depressed Alzheimer’s patients were less likely to have sleep disturbances or feelings of worthlessness or excessive guilt than non-demented depression patients, but were more likely to have problems concentrating or making decisions.
The results of this same study confirmed other research showing that the prevalence of major depression did not increase with the severity of Alzheimer’s disease. This may mean that major depression in Alzheimer’s is not related to the overall degeneration of the brain, but rather to degeneration in specific areas. In fact, several studies have shown that major depression in Alzheimer’s disease patients is associated with the degeneration of the areas of the brain stem that produce mood-regulating chemicals such as serotonin, noradrenaline, and dopamine. It’s unclear whether this is relevant for other types of dementia.
Dr. Zubenko is one of a group of scientists proposing that the next update of the Diagnostic and Statistical Manual of Mental Disorders (a reference manual used by doctors in the U.S.) include more accurate characterizations of various psychiatric symptoms in dementia, including depression. Better diagnosis would be another step towards understanding the causes of and treatment for depression in Alzheimer’s.
In the meantime, can doctors help AD patients with depression? Most clinical trials of anti-depressants for depression in Alzheimer’s have been relatively small and short term. At first glance, results look mixed, with some trials showing anti-depressants were more effective than placebo, and some not. In one larger study of 511 patients, an anti-depressant significantly improved both depression and memory. Research currently underway may yield more information. Israeli researchers are conducting a trial of Escitalopram (Lexapro, Cipralex)) for depressive syndrome in various dementias, and there’s also a U.S.-based trial of Zoloft for depression in Alzheimer’s disease.
But the published trial results are really more positive than it first appears, because many show large improvements in the patients taking antidepressants AND in those taking placebos. For example, researchers from the Raul Carrea Institute of Neurological Research in Argentina published the results of a trial of anti-depressants in 41 depressed Alzheimer’s patients. The symptoms of depression went away in 47% of patients treated with the anti-depressant, and in 33% of those treated with placebo. The large placebo effect may be due to non-drug factors such as the attention paid to patients and caregivers during clinical trials, or to the fact that depression in Alzheimer’s patients seems to come and go. Even though it’s not well understood, Dr. Zubenko says this finding means doctors can provide some assistance for AD patients with depression.
“The goals of most controlled clinical trials are somewhat different from the goals of clinical care,” he explains. “Most controlled clinical trials are designed to evaluate whether a particular treatment is effective. To accomplish this, the only difference between the treatment and control groups is the specific treatment whose potential benefit is being evaluated. These controlled trials are important because they provide scientific information from which healthcare professionals and caregivers can decide what treatments work for a particular condition and which do not. Doctors recommend treatment plans for individual patients based on this information, but are not limited to one particular treatment approach. In such cases, we often recommend multiple interventions to maximize the likelihood of a beneficial response, hopefully in an organized way, so that we can also infer which interventions are benefiting the patient. This practical approach is especially important when time is of the essence--e.g the patient's condition is deteriorating in ways that place them in harm's way, they are dangerous to others, or when other practical realities limit the available duration of treatment (such as often occurs in inpatient settings).”
Medications are helpful, but “nonspecific clinical interventions can have valuable effects on optimizing function and minimizing disability,” Dr. Zubenko says. “Patients who are in physical pain or discomfort, or are impaired in other ways by medical problems or medication side effects, commonly have secondary disturbances of mood and cognition. Performing a complete medical evaluation and optimizing general health care can have significant positive effects on level of function and the quality of life. Supportive care is also important-- improving nutrition among malnourished patients, addressing personal hygiene, normalizing and structuring daily activities, providing a safe environment with activities and aids that facilitate memory and promote normal functioning , and reevaluating these plans periodically to ensure that they remain appropriate to the patient's needs. Based on my clinical experience, major depression in AD patients usually responds best to a multimodal treatment approach.
It's also important to remember that the ongoing care of a patient with AD is a challenging task for the caregiver. Over the intermediate and long term, it is necessary to provide support, education, assistance, and resources to the caregivers as well. Proper attention and support reduces the stress on caregivers and decreases or delays the need for institutionalization. Failure to do so results in poorer outcomes for both patients and caregivers alike.”
So, major depression and dementia are closely linked, and our understanding of causes and treatments for both of these diseases is still incomplete. For depression sufferers around the world, there’s an increased risk of AD. And for Alzheimer’s patients around the world, there’s a potential depressive ripple effect, for both patients and caregivers.
Careful medical attention for both the patient and the caregiver may help, but I wonder how many patients and caregivers can get this attention. In my family’s experience, it was difficult to coordinate Dad’s care between his family physician and his neurologist, let alone “optimize” all the factors Dr. Zubenko talks about. If my father had lived long enough to need intensive caregiving, only minimal assistance and resources would have been available to us.
It’s hard to find the silver lining in this research, but Dr. Zubenko put it in perspective for me. “We’re trying to treat a complicated behavioral syndrome in the context of degenerative brain disease – any progress is remarkable, and efforts to optimize treatment are well worth it for patients and their family members,” he says.