Steroid Hormones, Dopamine and ADHD: Key Biological Pathways
1. Cholesterol
Steroid precursor and essential structural molecule
Cholesterol is the starting material for the synthesis of all steroid hormones.
Key roles
- Precursor for pregnenolone, and subsequently progesterone, cortisol, aldosterone, testosterone and oestrogens
- Essential component of cell membranes
- Precursor for vitamin D and bile acids
- Important for myelin formation and normal nervous-system function
- Synthesised largely in the liver, although most tissues can produce cholesterol locally
- Transported in the circulation within lipoproteins, including LDL and HDL
Key biochemical step
Cholesterol → Pregnenolone, catalysed by CYP11A1 (P450scc) within mitochondria.
2. Pregnenolone
First major steroid precursor
Pregnenolone sits near the beginning of steroid-hormone synthesis and can enter several different metabolic pathways.
Key roles
- Produced from cholesterol in steroid-producing tissues including the adrenal glands, gonads and brain
- Precursor to progesterone, glucocorticoids, mineralocorticoids, androgens and oestrogens
- Also functions as a neurosteroid
Brain relevance
Pregnenolone and its metabolites can influence neurotransmitter systems including GABA and glutamate/NMDA signalling. Research into effects on cognition, mood and neuroplasticity is ongoing, but these effects should not be presented as established ADHD treatments or mechanisms.
3. Progesterone
Reproductive hormone and neuroactive steroid
Progesterone has important reproductive and neurological functions.
Key roles
- Regulates the menstrual cycle
- Supports pregnancy
- Serves as an intermediate in steroid-hormone synthesis
- Can be metabolised to neuroactive steroids such as allopregnanolone
- Influences GABA-A receptor signalling
- Contributes to immune and inflammatory regulation
ADHD relevance
Changes in progesterone and its relationship with oestrogen across the menstrual cycle may contribute to changes in cognition, mood and ADHD symptoms in some women, although the mechanisms remain incompletely understood.
4. Testosterone
Principal androgen
Testosterone is present in all sexes, although circulating concentrations are substantially higher on average in males.
Key roles
- Sexual development and reproductive function
- Maintenance of muscle mass
- Supports bone density
- Influences libido
- Supports red blood cell production
- Contributes to brain development and behaviour
Metabolism
- Testosterone → DHT via 5α-reductase
- Testosterone → Estradiol via aromatase (CYP19A1)
Brain relevance
Androgens interact with dopaminergic and other neurotransmitter systems, but there is currently insufficient evidence to describe testosterone as directly causing or worsening ADHD.
5. Dihydrotestosterone — DHT
Potent androgen derived from testosterone
DHT is formed from testosterone through the enzyme 5α-reductase.
Key roles
- Important in male genital development
- Contributes to facial and body hair growth
- Influences prostate development and function
- Plays a role in androgen-dependent tissues
- Associated with androgenetic hair loss in genetically susceptible individuals
Its specific role in ADHD remains uncertain and should not currently be presented as a recognised ADHD mechanism.
6. Oestrogens
Estradiol, estrone and estriol
Oestrogens are important reproductive hormones with widespread effects throughout the body and brain.
Key roles
- Regulation of the menstrual cycle and reproductive system
- Maintenance of bone health
- Effects on cardiovascular and metabolic systems
- Influence on mood, cognition and neural plasticity
- Modulation of several neurotransmitter systems
Brain and ADHD relevance
Estradiol can influence dopamine synthesis, release, receptor function and transporter activity. This is one plausible mechanism through which hormonal fluctuations may influence attention, motivation and executive functioning.
Some women with ADHD report symptom worsening during phases of falling or lower oestrogen, particularly premenstrually and during perimenopause. The evidence is increasingly suggestive, but the relationship is not identical in every woman.
7. Cortisol
Major glucocorticoid and stress-response hormone
Cortisol is produced by the adrenal cortex as part of the hypothalamic-pituitary-adrenal (HPA) axis.
Key roles
- Coordinates the physiological stress response
- Helps regulate blood glucose
- Influences metabolism
- Modulates inflammatory and immune activity
- Follows a normal circadian rhythm
ADHD relevance
Stress can worsen attention, working memory, emotional regulation and executive functioning. However, ADHD should not be described simply as a disorder of high cortisol or reduced dopamine caused by cortisol. Research into HPA-axis regulation in ADHD has produced mixed findings.
8. Aldosterone
Mineralocorticoid regulating fluid and electrolyte balance
Aldosterone is produced by the adrenal cortex.
Key roles
- Promotes renal sodium retention
- Promotes potassium excretion
- Helps regulate blood volume
- Contributes to blood-pressure control
- Forms part of the renin-angiotensin-aldosterone system
Aldosterone does not currently have a major established role in ADHD biology.
Dopamine and ADHD
9. Dopamine
Neurotransmitter involved in motivation, reward and executive control
Dopamine is one of the neurotransmitter systems most strongly implicated in ADHD.
Key functions
- Motivation and effort allocation
- Reward processing
- Reinforcement learning
- Attention
- Working memory
- Movement
- Decision-making and behavioural control
ADHD relevance
ADHD is not simply caused by “low dopamine.” Current models point instead to altered regulation of dopaminergic and noradrenergic networks, particularly within frontostriatal and frontocerebellar circuits.
Stimulant medications improve ADHD symptoms partly by increasing the availability of dopamine and noradrenaline in relevant neural circuits.
10. Dopamine Receptors
Sites through which dopamine exerts its effects
Five main dopamine-receptor subtypes are recognised: D1, D2, D3, D4 and D5.
For a simplified ADHD model, D1- and D2-family signalling is particularly relevant.
D1-family receptors
- Important in prefrontal cortical function
- Contribute to working memory
- Support attention and goal-directed behaviour
D2-family receptors
- Important within the striatum and reward circuitry
- Influence motivation, reinforcement learning, movement and habit formation
ADHD relevance
ADHD is associated with differences across dopamine-related pathways, but it is too simplistic to state that ADHD results directly from “damaged” or “desensitised” dopamine receptors.
Hormone Metabolism and Clearance
Liver processing, conjugation and excretion
Steroid hormones are continuously synthesised, transformed and cleared.
Phase I metabolism
Predominantly involves enzymes including the cytochrome P450 family.
These reactions may:
- hydroxylate hormones
- oxidise or reduce steroid molecules
- convert hormones into active or less-active metabolites
Phase II metabolism
Includes processes such as:
- glucuronidation
- sulfation
These reactions increase water solubility and facilitate elimination.
Excretion
Hormone metabolites are subsequently eliminated through:
- urine
- bile and faeces
Hormonal regulation therefore depends on the balance between production, conversion, receptor activity and clearance.
How Hormones May Interact With ADHD
The relationship is best understood as an interaction rather than a simple one-hormone/one-symptom model.
Oestrogen
→ Can enhance several aspects of dopaminergic and noradrenergic neurotransmission. Falling oestrogen may contribute to worsening attention, executive function or emotional regulation in some women.
Progesterone and neurosteroids
→ Influence GABAergic signalling and may modify mood, arousal and cognition across the menstrual cycle.
Testosterone and other androgens
→ Interact with dopamine and brain development, but their contribution to sex differences in ADHD remains uncertain.
Cortisol and stress systems
→ Acute or chronic stress can impair executive functioning and amplify ADHD-related difficulties, although cortisol abnormalities are not considered the primary cause of ADHD.
Dopamine and noradrenaline
→ Dysregulation within catecholamine networks affecting the prefrontal cortex, striatum and associated circuits forms an important part of contemporary ADHD neurobiology.
The important distinction
ADHD is not simply a “dopamine deficiency”, and female ADHD is not simply an “oestrogen deficiency”.
A more accurate model is:
Genes + brain development + catecholamine regulation + neural networks + environment + sleep + stress + reproductive hormonal state → variation in ADHD symptom expression and functioning.