Depression’s connection to dementia is clearer


A substantial body of research has linked late-life depression (over age 50) to social isolation, poorer health, and an increased risk of death. These are invaluable findings, useful broad-brush generalizations—an aerial view of the landscape.

Now, a new study has drilled down into individual cases and found that vascular dementia and Alzheimer’s disease are also linked to late-life depression.

This finding deserves recognition as big news, considering the dramatic increase in these conditions that we’ll see as the already aging population ages further.

The research gives us more invaluable insight into identifying, tracking, and hopefully preventing or reversing these debilitating conditions.

The two faces of dementia

Let’s first be sure we know the similarities and differences between vascular dementia and Alzheimer’s disease. They’re sometimes used interchangeably, leading to much confusion. To me, they’re two different types of dementia.

Vascular dementia is often caused by an acute, specific event such as a stroke, where the blood flow to the brain has been interrupted. It can also develop more gradually over time from very small blockages or the slowing of blood flow. It’s estimated to affect between 1 and 4 percent of people over 65. The percentage doubles every 5 to 10 years after age 65.

According to the National Institute on Aging (NIA), vascular dementia affects the part of the brain associated with communication and performance of daily activities.

Alzheimer’s is a type of dementia that affects different parts of the brain, those that control thought, memory, and language. The exact cause—or more likely, causes—are not yet known. Many factors may contribute, including genetics, lifestyle, and other environmental factors. Alzheimer’s is by far the most common kind of dementia, affecting more than 5.7 million Americans.

 So where does the new research take us?

The report, published in the British Journal of Psychiatry, analyzed 23 previous studies that followed nearly 50,000 adults older than age 50 over a median of five years.

The researchers found that depressed adults, compared to those who weren’t depressed:

  • Had double the likelihood of developing vascular dementia
  • Were 65 percent more likely to develop Alzheimer’s disease

This isn’t proof that late-life depression causes vascular dementia or Alzheimer’s, but it’s a strong suggestion that depression is a contributing factor to both.

Crunching the numbers suggests that:

  • 72 percent of older adults with late-life depression may go on to develop vascular dementia
  • 62 percent of seniors with a history of depression may eventually be diagnosed with Alzheimer’s

In both cases, for well more than half of those with late-life depression, it appears that things can go from bad to worse.

NIH already calls Alzheimer’s an epidemic. As the at-risk population grows, is a super-epidemic on the horizon?  Can it be stopped, or at least slowed? Millions of lives are at stake.

Is depression a double villain?

We know from previous research that a history of depression is linked to a doubling of the risk of ending up with Alzheimer’s disease.

This is the first research showing a stronger association between late-life depression and vascular dementia than we previously thought.

This would suggest that late-life depression can signal either vascular dementia or Alzheimer’s.

If that’s the case, how does late-life depression do its dirty work? What biological mechanisms might account for a relationship between depression and dementia?

If we can answer that question, where does that take us?

Can we find solid evidence that forestalling late-life depression will prevent both vascular dementia and Alzheimer’s? And put into place everything we know that can keep depression at bay?

What a giant step toward health and well-being that would be. Imagine lifting a dreadful personal tragedy for patients and caregivers, and a heavy burden on our healthcare system and economy writ large.

No wonder there’s so much research underway to answer these questions.

Where the answers might be found

“We think depression is toxic to the brain, and if you’re walking around with some mild brain damage, it will add to the degenerative process,” said Meryl Butters, an associate professor of psychiatry at the University of Pittsburgh School of Medicine and a co-author of the recent research.

Says another expert, Dr. Raymond Ownby, chair of psychiatry at Nova Southeastern University’s College of Osteopathic Medicine, who studies the possible links between depression and dementia:

“We know that people who are depressed have elevated levels of cortisol, a hormone related to the stress response, and a smaller hippocampus, a brain structure critically important for memory.”

Other evidence suggests that depression contributes to chronic inflammation, which damages blood vessels and impedes blood flow in the brain, leading over time to the deterioration of neural networks. I totally buy this approach—chronic inflammation is the fiery devil at the root of every known disease.

It’s also possible that depression shares genetic links with vascular dementia, and fires up the first genes in what research could finally show is a recognizable trajectory from depression to vascular dementia, Alzheimer’s, or both.

This angle of attack would recognize that the earliest signs of cognitive impairment are the first step along that pathway, giving us warning of impending dementias at the earliest possible moment.

Whatever the underlying mechanisms may be, the implications for older adults are clear. “If someone in later life develops depression, they should get early, aggressive treatment, and if they do so and recover, they should try to prevent recurrence,” Dr. Butters said.

While there is no solid evidence that doing so will prevent dementia, treating depression in older adults at least improves their quality of life, relieving suffering and reducing other health risks.

Fine-tuning the types of depression

A study in The Netherlands monitored the health of a group of adults aged over 55. Researchers followed 3,325 people who were dementia-free when the study began but showed signs of depression as the study progressed over an 11-year period.


The study identified five different trajectories of depression:

  1. Stable low levels of depression
  2. Decreasing depression
  3. Remitting depression—high levels of depression followed by a period of improvement
  4. Steadily increasing depression
  5. Stable high levels of depression

The group with steadily increasing depression over time was at a greater risk of dementia than people with low levels of depression.

Knowing this gives us important guidance as to which adults, with which type of depression, should be targeted for aggressive intervention as Dr. Butters suggests above.

Tantalizingly close to conclusive

So the bottom line in this particular research is that steadily increasing symptoms of depression in later life may be an early indicator of vascular dementia or Alzheimer’s.

And the aggregate bottom line of all of this research and more is that in many instances, for many people, late-life depression seems almost certainly a contributing factor to vascular dementia or Alzheimer’s.

There is no proven cause or cure for depression—yet. But I can feel it growing closer.

In the meantime, until that moment of proof arrives, we don’t have to wait and wonder whether depression will or will not disrupt our lives.

We’re not helpless.

Natural depression remedies

A growing body of evidence shows that adequate dietary intake of omega-3s not only keeps depression from developing—it can also reduce symptoms in those already suffering.

Please note that I recommend omega-3s only for cases of mild to moderate depression—not severe depression. If signals of severe depression are present—trouble with daily tasks or thoughts of harming yourself or others, you must report them to your doctor immediately.

I recommend starting with a minimum 1,500 mg/day omega-3 supplement.

5-Hydroxytryptophan (5-HTP) is made from the seeds of an African plant long used to treat depression and many other disorders and diseases.

It works by increasing the production of serotonin, a neurotransmitter that regulates our mood. Upping the body’s natural serotonin level has been shown to reduce anxiety, and ease the dark, debilitating emotional symptoms of depression.

For daytime relief, take one or two 50 mg doses. To help you sleep, take 100-200 mg.

The B-Vitamins play an A-team role in maintaining nervous system functions. It’s a group of eight specific vitamins, known by a number, e.g., B-12, or by name: thiamine, riboflavin, niacin, and so on.

Together, in a B-complex formula, they help turn food into energy, help create new red blood cells, and help build your brain’s chemical messengers. Individually, each B vitamin also serves its own purpose in the nervous system.

B-12, for example, protects nerve coverings and fights back against homocysteine, a compound associated with depression and linked to stroke and cardiovascular disease.

Older patients are especially at risk for B-12 deficiency—their reduced amount of stomach acid means reduced absorption of the vitamin.

I recommend a high-quality B-complex multivitamin to cover all the bases. Consult with your doctor about increasing amounts of individual B vitamins to tackle specific problems.

Saffron is one of the most trusted and effective mood boosters and depression lifters we know. What we don’t know is exactly how it works, though it’s very likely that increased serotonin production plays a role. Research is ongoing to track down the reasons, but saffron’s long empirical history assures us that it’s perfectly safe and effective (though not for people with bipolar disorder). Saffron 30 mg daily in 2 divided doses is effective in improving symptoms of mild to moderate depression.

Rhodiola is one of those wonderful adaptogens—substances that roam around the body, improving the function of just about anything they bump into. It’s been used as a multi-tasking healer throughout Europe and Asia since forever.

As an adaptogen, it helps the body adapt to and resist physical, mental, and environmental stress. It’s used to do everything from improving cognitive function to preventing liver damage to improving hearing and more. Several studies have found that self-assessment of general well-being improves among subjects taking a rhodiola supplement—evidence of a depression-easing effect. I recommend rhodiola tea in the morning.

Phenylalanine is an amino acid essential for building protein. The body changes phenylalanine into tyrosine, another amino acid that is needed to make proteins and brain chemicals. Among these chemicals are L-dopa, epinephrine, norepinephrine, and thyroid hormones—all found to affect mood, and therefore to treat depression, though the exact mechanism isn’t yet known. Anecdotal and empirical evidence, however, including study subjects’ self-reported feelings of “mood improvement,” offer positive support for phenylalanine’s efficacy.

I have my patients take DLphenylalanine—750 mg twice daily, preferably at breakfast and lunch. People with a rare disorder known as phenylketonuria (PKU) should not use phenylalanine.

There’s excellent evidence that St. John’s Wort is good news—reducing symptoms of mild-to-moderate (not severe) depression as effectively as heavy Big Pharma hitters like Prozac and Zoloft—but without the nasty side effects.

It seems to work the same way as other natural remedies, increasing production of serotonins and other mood-lifting brain chemicals. Try 30 mg daily in 2 divided doses to improve symptoms of mild to moderate depression.

I can’t exit without emphasizing that every cell in your body will be a healthier cell if you increase your physical activity, even for just a few minutes a day. The same goes for maintaining a stimulating social life. Good friends and family are very good medicine.

And finally, depression can be a dark and scary place. While my suggestions above are backed by well-conducted research, everyone’s situation is different. If depression is standing in the way of your ability to work, socialize, pay your bills or otherwise take care of yourself or your responsibilities, please do reach out to a qualified therapist.

Take good care.



Last Updated: August 16, 2018
Originally Published: June 28, 2018