Dementia & Depression:  A Connection

Until recently, researchers had no idea that there was a relationship between dementia and depression. Does depression cause dementia, or vice-versa? Do these problems occur independently from one another, or do they simultaneously affect the same regions of the brain? Researchers think they have discovered an answer: Depression is a risk factor for dementia.

Brain Cell Death

Dementia is an overarching diagnosis for decreased mental ability including memory, concentration, communication, and other daily tasks. One popular form of dementia is Alzheimer’s disease. Doctors can identify dementia in patients through the use of physical examinations, lab work, medical history, and the analysis of behaviors and memory tests. Many times doctors will be unable to diagnose a subtype of dementia, but its prevalence in a patient is clear.

Brain cell damage can lead to dementia. This damage leads to an inability for the cells to communicate with one another, leading to a range of difficulties. Varying regional damage in the brain is related to different subtypes of dementia. For instance, Alzheimer’s is associated with damage to the hippocampus (a region of the brain that controls memory and learning). When brain cells in the hippocampus are injured, messages about learning new tasks, how to perform already learned tasks, or who somebody is may be broken.

The hippocampus also helps regulate mood. Some brain scans of people with depression indicate smaller hippocampal regions than people who have never experienced depression. When the hippocampus is smaller, it contains fewer serotonin receptors. A lack of serotonin reception and production is another cause of depression for many people. Cell growth in the hippocampus may be the key to treating people with depression.

Growing New Brain Cells

A study published in Science demonstrates how neurogenesis (the birth of new brain cells) in the hippocampus can lead to a decrease in depressive symptoms. While studying the effects of anti-depressant drugs on laboratory animals, the researchers discovered that antidepressant use increased neurogenesis. This cell growth took the same time as antidepressants take to affect human adults, reflecting the activity of adult human neurogenesis. Then, the researchers studied primates’ neurogenesis while under stress and determined that stress can limit cell growth. When antidepressants were used, neurogenesis stabilized.

Why are these findings important? 

1. The hippocampus of depressed patients is typically smaller, and the hippocampus regulates mood and memory. 

2. If neurogenesis in the hippocampus can improve mood and memory, and if antidepressants can help with neurogenesis, then the use of antidepressants and other future treatments for hippocampal growth are promising. Of course, depression and its treatments are not one-size-fits-all, but in treating depression by means of cell growth in the hippocampus, physicians could also help patients boost their memories.

Depression Causes Risk of Dementia

According to research from the Rush Medical Center, people with depression are more at risk for dementia later in life. In fact, the researchers determined that 52% of their depressed participants developed Mild Cognitive Impairment, and 18% developed dementia. Those participants that developed MCI and/or dementia typically had more severe depressive symptoms prior to the onset of MCI and dementia diagnoses.  

A Mayo Clinic study of patients with Alzheimer’s and Lewy body dementia demonstrated that participants with already existing Mild Cognitive Impairment and depression were 66% more likely to develop dementia than those with Mild Cognitive Impairment without depression. These findings indicate that treating and preventing depression may help prevent and alleviate symptoms caused by MCI and dementia.

Techniques for Treating Depression & Dementia

• Exercise and physical activity have shown promise in improving symptoms of depression, but it can also benefit people struggling with dementia by boosting cognitive functioning, improving sleep cycles, and providing people with more energy.

• Adding structure to daily activities may also help people with depression by feeling in control of their lives. This structure may also assist with memory function. Classes, games, reading, writing, and looking at pictures of loved ones may provide therapeutic benefits and strengthen cognitive activities.

• Social interaction not only gives people the opportunity to form meaningful relationships and add pleasure to their lives, but communication can increase brain activity. Looking forward to interacting with others may decrease isolation, which can ward off cognitive and mood issues.

• Psychotherapy and group therapy may assist in the healing process. These interventions can give people strategies to work through their depression and dementia, and may also make people feel less “alone” in their struggles.

• SSRI Medication may also assist people who suffer from dementia and depression. SSRIs (selective serotonin reuptake inhibitors), like Celexa, Zoloft, Lexapro, and Prozac can add as a supplement to the previously mentioned therapies, but they are not a replacement.  Ignoring the other treatments and relying only upon SSRI's could cause complications. Not everybody will need or benefit from medication, and it is important to identify the correct fit for each individual. However, the use of medication may improve the brain’s reception and production of chemicals that decrease symptoms of depression and dementia.

- Melissa Lavery, M.S.
 
References

Causes of Depression: Genetics, Illness, Abuse, and More. (2014, February 8). Retrieved January 16, 2015, from http://www.webmd.com/depression/guide/causes-depression#2

Eisch, A., & Petrik, D. (2013, August 29). Depression and Hippocampal Neurogenesis: A Road to Remission? Retrieved January 16, 2015, from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3756889/

Heerema, E. (2013, September 26). Treatment of Depression in Dementia. Retrieved January 16, 2015, from http://alzheimers.about.com/od/treatmentofalzheimers/a/Treatment-Of-Depression-In-Dementia.htm

Mayo Clinic. (2010, July 16). Apathy and depression predict progression from mild cognitive impairment. ScienceDaily. Retrieved January 16, 2015 from www.sciencedaily.com/releases/2010/07/100712115100.htm

Rush University Medical Center. (2014, July 30). Depression as a risk factor for dementia: Link is independent of dementia-related brain changes. ScienceDaily. Retrieved January 16, 2015 from www.sciencedaily.com/releases/2014/07/140730161525.htm

What Is Dementia? (n.d.). Retrieved January 16, 2015, from http://www.alz.org/what-is-dementia.asp