(MayoClinic.com) Early Alzheimer's disease and depression share many symptoms, so it can be difficult even for doctors to distinguish between the two disorders. And many people with Alzheimer's also are depressed.

One important difference between Alzheimer's and depression is in the effectiveness of treatment. While Alzheimer's drugs can only slow the progression of cognitive decline, medications to treat depression can improve a person's quality of life dramatically.

People who have both Alzheimer's and depression may find it easier to cope with the changes caused by Alzheimer's when they feel less depressed.

Some of the symptoms common to both Alzheimer's and depression include:

• Loss of interest in once-enjoyable activities and hobbies
• Social withdrawal
• Memory problems
• Sleeping too much or too little
• Impaired concentration

With so much overlap in symptoms, it can be hard to distinguish between the two disorders, especially since they so often occur together. A thorough physical exam and psychological evaluation can be helpful in determining a diagnosis. However, many people with moderate to severe Alzheimer's disease lack both the insight and the vocabulary to express how they feel.

To detect depression in people who have Alzheimer's disease, doctors must rely more heavily on nonverbal cues and caregiver reports than on self-reported symptoms. If a person with Alzheimer's displays one of the first two symptoms in this list, along with at least two of the others within a two-week period, he or she may be depressed.

• Significantly depressed mood — sad, hopeless, discouraged, tearful
• Reduced pleasure in or response to social contacts and usual activities
• Social isolation or withdrawal
• Eating too much or too little
• Sleeping too much or too little
• Agitation or lethargy
• Irritability
• Fatigue or loss of energy
• Feelings of worthlessness, hopelessness or inappropriate guilt
• Recurrent thoughts of death or suicide

People with Alzheimer's may experience depression differently from that of people without Alzheimer's. For example, individuals diagnosed with Alzheimer's disease:

• May have symptoms of depression that are less severe
• May experience episodes of depression that don't last as long or come back as frequently
• Talk of suicide and attempt suicide less often
• May experience hallucinations or delusions

Scientists aren't sure of the exact relationship between Alzheimer's disease and depression. Some research has found that the biological changes caused by Alzheimer's may intensify a predisposition to depression. Other studies suggest that the presence of depression may increase your chances of developing Alzheimer's disease.

It's clear that depression has a strong effect on quality of life for people with Alzheimer's disease. Depression can lead to:

• Faster cognitive decline
• Greater disability involving daily living skills
• Increased dependence on caregivers
• Earlier placement in nursing homes

Several options are available to treat people diagnosed with Alzheimer's disease and depression:

• Antidepressants. Selective serotonin reuptake inhibitors (SSRIs) — for example, citalopram (Celexa) and sertraline (Zoloft) — are the first antidepressants used for people who have depression and Alzheimer's because of the low risk of side effects and drug interactions. However, these medications may not be as effective at treating depression with Alzheimer's as they are at treating depression alone. Other antidepressants, such as venlafaxine (Effexor XR) or bupropion (Aplenzin, Wellbutrin, others), also may be used.
• Physical exercise. Regular physical exercise, particularly in the morning, may help ease the symptoms of depression.
• Support groups and counseling. Support groups and professional counseling may help people with depression in the early stages of Alzheimer's disease, before their communication skills deteriorate.
• Electroconvulsive therapy. Some people with depression and dementia don't respond to other treatments. In many of these cases, electroconvulsive therapy can help relieve symptoms of severe depression. This procedure delivers electricity to the brain for a few seconds to deliberately trigger a brief seizure.

Making the right diagnosis and getting appropriate treatment can help make life easier and more enjoyable for both the person with Alzheimer's and his or her caregivers.

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