From the Guidelines
Alcohol use causes autonomic dysfunction by directly damaging the autonomic nervous system, with chronic consumption leading to secondary autonomic failure, as indicated in a study published in the European Heart Journal 1. This damage can occur through various mechanisms, including the toxic effects of ethanol and its metabolite acetaldehyde on nerve fibers, particularly small unmyelinated and lightly myelinated autonomic fibers. Key factors contributing to autonomic dysfunction in alcohol use include:
- Direct toxicity to nerve fibers
- Nutritional deficiencies, especially thiamine (vitamin B1) deficiency
- Alterations in neurotransmitter systems, such as GABA, glutamate, and norepinephrine, which regulate autonomic functions The severity of autonomic dysfunction typically correlates with the duration and amount of alcohol consumed, with some improvement possible after abstinence, though severe cases may result in permanent damage, as suggested by the guidelines on management of syncope 1. Some of the symptoms of autonomic dysfunction caused by alcohol use are:
- Orthostatic hypotension
- Impaired heart rate variability
- Abnormal sweating patterns
- Digestive issues
- Urinary problems
- Sexual dysfunction Treatment of autonomic dysfunction caused by alcohol use focuses primarily on alcohol cessation, nutritional supplementation, and management of specific symptoms, with the goal of improving morbidity, mortality, and quality of life outcomes.
From the Research
Autonomic Dysfunction and Alcohol Use
- Autonomic dysfunction is a known consequence of chronic and excessive alcohol consumption, with 16-73% of chronic alcohol abusers suffering from this condition 2.
- The most commonly occurring symptom of autonomic dysfunction in alcohol abusers is erectile dysfunction, while other features such as postural dizziness are rare 2.
- The total lifetime dose of ethanol is the most important risk factor for autonomic dysfunction in alcohol abusers, although there is mixed evidence supporting the role of other risk factors 2.
Pathophysiology of Autonomic Dysfunction
- Autonomic dysfunction can be caused by failure of noradrenergic neurotransmission, which is associated with a range of primary or secondary autonomic disorders 3.
- Alcohol use can lead to autonomic dysfunction by damaging the parasympathetic division of the autonomic nervous system, as evidenced by decreased heart rate variation at rest and postural pulse reaction in alcoholics 4.
- Autonomic dysfunction can also be associated with impaired gut-brain communication, which can lead to functional gastrointestinal disorders (FGID) and gastroesophageal reflux (GERD) disease 5.
Diagnosis and Management of Autonomic Dysfunction
- Heart rate variability (HRV) can be used to assess autonomic function and dysfunction in patients with FGID and GERD, with decreased parasympathetic activity and increased sympathetic nervous system activity observed in these patients 5.
- Diagnosis of autonomic dysfunction can also involve measurement of heart rate and plasma norepinephrine responses to orthostatic stress, as well as cardiac sympathetic denervation diagnosed with MIBG scintigraphy or 18F-DA PET scanning 6.
- Abstinence from alcohol appears to lead to significant improvement in autonomic investigations, and is currently the only management strategy explored in the literature for autonomic dysfunction in alcohol abusers 2.