ADHD, anxiety, and depression: The overlap and interplay

ADHD, anxiety, and depression often show up together. When they do, this can lead to a complicated relationship, where the symptoms of one condition may worsen symptoms of the others.

ADHD and anxiety

Nearly 1 in 2 people with ADHD have at least one anxiety disorder.¹

Struggling with ADHD symptoms like organisation difficulties, missing deadlines, and acting impulsively can lead to anxiety over time.

Example: Imagine someone with ADHD who struggles to stay focused and finish tasks. Because they keep missing deadlines or forgetting things, they start to feel anxious about work or letting others down.

That anxiety makes it even harder to concentrate or stay calm, which are already challenges with ADHD.

The more anxious they get, the harder it is to manage their ADHD.

So, it becomes a cycle: ADHD causes anxiety, and anxiety makes ADHD symptoms worse.

Why does this happen?

Research shows that anxiety can make ADHD symptoms worse by affecting brain activity. This happens especially in areas that help with focus and memory, like the cerebellum, caudate nucleus, putamen, and thalamus.

For example, people with higher anxiety levels tend to have lower activity in the cerebellum, a part of the brain that helps you think clearly and tune out distractions.

But this part of the brain is already less active if you have ADHD. So anxiety can make it even harder to concentrate, sort, and process information.^[1]

ADHD and depression

ADHD is often linked to depression. Adults with ADHD are three times more likely to experience depression than those without it.^[2]

And the risk of depression increases 6.5 times within the first year of an ADHD diagnosis.[3]

One reason might be how people with ADHD tend to handle stress. They often use avoidant coping, which means avoiding hard or stressful tasks instead of tackling them.

Example: If you have ADHD, you might struggle with starting big tasks, like writing a report for work. So every time you think about it, you may feel overwhelmed because there are too many steps, and you’re not sure where to begin.

So instead of facing it, you might avoid the task altogether.

This approach can cause problems to build up or affect other areas of life, which may worsen depression symptoms over time.^[3]

Some symptoms of adult ADHD and depression can overlap, which can make diagnosing them challenging.

For example, both conditions can affect:

• focus at work or on tasks;
• sleep; and:
• appetite (especially if you take stimulant medication).

But some symptoms are specific to depression and don’t overlap with ADHD, including:

• persistent feelings of sadness or emptiness;
• guilt;
• hopelessness;
• worthlessness;
• loss of interest in hobbies and activities; and:
• recurring thoughts of death or suicide.

Why do they overlap?

The overlap between ADHD, anxiety, and depression is complex. But research suggests that the following factors may play a role:

The role of genes

Studies suggest that ADHD, anxiety, and depression may be connected through genes.

So if someone in your family has ADHD, anxiety, or depression, it could be because of shared genes passed down through generations. These genes can make it more likely for others in the family to have the same issues.

And if you have the genes that make you more likely to have one condition, you might be at higher risk for the others, too.

Many different genes are thought to contribute to the connection between ADHD, anxiety, and depression.^3,4

Some of them affect dopamine, a brain chemical that helps regulate mood, motivation, and focus, things that are often affected in ADHD, anxiety, and depression.⁵

The role of environment

Research says that ADHD, anxiety, and depression are often caused by a mix of environmental factors.

Some of the factors that can raise the risk of all three conditions include:

• Exposure to nicotine or alcohol during pregnancy.⁶
• Toxins like lead, pesticides, and air pollution.⁷
• Adverse life factors like poverty, frequent conflict at home, large family size, or having a parent with mental health or legal issues.⁸
• Life stressors like bullying, trauma, or being placed in foster care.⁹

The role of brain chemicals

Brain chemicals seem to play a big part in ADHD, anxiety, and depression.

In ADHD, the brain often has lower levels of dopamine and norepinephrine. These chemicals help with things like focus, attention, and motivation.¹⁰

When dopamine is low, it can make you feel distracted, restless, or act on impulse. It also affects your brain’s reward system. So feeling motivated or enjoying things can be harder.¹¹

Since dopamine is also linked to anxiety and depression, this may help explain why these conditions often show up together.

References:

1. van der Meer, D., et al. (2017). Anxiety modulates the relation between attention-deficit/hyperactivity disorder severity and working memory-related brain activity. The World Journal of Biological Psychiatry, 19(6), pp.450–460.
2. Bron, T. I., et al. (2016). Prevalence of ADHD symptoms across clinical stages of major depressive disorder. Journal of Affective Disorders, 197, pp.29–35.
3. Riglin, L., et al. (2020). ADHD and depression: investigating a causal explanation. Psychological Medicine, 51(11), pp.1–8.
4. Ohi, K., et al. (2019). Shared genetic etiology between anxiety disorders and psychiatric and related intermediate phenotypes. Psychological Medicine, 50(4), pp.692–704.
5. Kanarik, M., et al. (2022). ADHD co-morbidities: A review of implication of gene × environment effects with dopamine-related genes. Neuroscience & Biobehavioral Reviews, 139, p.104757.
6. Froehlich, T.E., et al. (2011). Update on Environmental Risk Factors for Attention-Deficit/Hyperactivity Disorder. Current Psychiatry Reports, 13(5), pp.333–344.
7. Koseva, N. (2023). Exploring the Links Between ADHD and Environmental Factors. The ADHD Centre.
8. Biederman, J. (1995). Family-Environment Risk Factors for Attention-Deficit Hyperactivity Disorder. Archives of General Psychiatry, 52(6), p.464.
9. Thapar, A., et al. (2011). What causes attention deficit hyperactivity disorder? Archives of Disease in Childhood, 97(3), pp.260–265.
10. del Campo, N., et al. (2011). The Roles of Dopamine and Noradrenaline in the Pathophysiology and Treatment of Attention-Deficit/Hyperactivity Disorder. Biological Psychiatry, 69(12), pp.e145–e157.
11. Volkow, N.D., et al. (2009). Evaluating Dopamine Reward Pathway in ADHD. JAMA, 302(10), p.1084.