Dementia is a clinical syndrome involving cognitive impairment and is generally associated with old age. The cognitive impairment and other behavioral and psychological symptoms observed in dementia arise due to neuronal damage caused by a variety of diseases. Chronic use of alcohol, illicit drugs and prescription medications can also increase the risk of cognitive impairment and dementia. Although substance use can cause or increase the risk of dementia, the role of dementia in substance abuse is not well studied.

Effects of Drug Use on Dementia

Although the use of alcohol and illicit drugs is associated with a higher risk of cognitive impairment, the evidence regarding whether these drugs, with the exception of alcohol, can cause dementia by themselves is mixed. However, there is evidence that drug abuse and prescription drugs can act on pathways that contribute to cognitive impairment and result in symptoms of dementia.

Alcohol and Dementia

The association between long-term alcohol use and cognitive decline is a matter of debate. Low-level use of alcohol is associated with a reduced risk of dementia relative to moderate or high levels of alcohol use or even abstinence. This is also true for the elderly. Chronic, heavy alcohol use can disrupt the availability of nutrients like thiamine (vitamin B) that are needed by the brain, or directly cause neuronal toxicity, resulting in alcohol-induced dementia. Chronic alcohol use is also associated with vascular-related pathologies including high blood pressure, hemorrhagic stroke and heart failure.

Marijuana and Dementia

Long-term marijuana use is associated with deficits in learning, retention and retrieval of memories and may increase the risk of dementia. Furthermore, the duration of marijuana use is correlated with the degree of deficits in learning and memory. Marijuana has also been claimed to have neuroprotective effects, but a small clinical trial studying the effects of marijuana on dementia showed no beneficial effects.

Anticholinergic Drugs

Anticholinergic drugs inhibit the action of the neurotransmitter acetylcholine, which is involved in various functions including muscle movements. Anticholinergic drugs are prescribed for bladder conditions, Parkinson’s disease and depression. However, acetylcholine also plays an important role in the central nervous system and is involved in mediating attention and memory-related functions. Consistent with this role, acute use of anticholinergic drugs can cause cognitive deficits and is associated with a higher risk of dementia. Chronic use may result in long-term modifications in the cholinergic neurons in the brain, resulting in cognitive impairment. Chronic use of anticholinergic drugs may also result in inflammation in the brain leading to the degeneration of neurons.

Prescription Drugs

Prescription drugs including benzodiazepines like Valium and Xanax are commonly used for the treatment of anxiety and insomnia but long-term use of benzodiazepines is linked with a higher risk of dementia. Heavy use of painkillers in the form of prescription opioids and nonsteroidal anti-inflammatory drugs (NSAID) is also associated with a higher risk of dementia.

Statistics on Dementia and Addiction

The epidemiology of the link between dementia and addiction has been best studied in relation to alcohol abuse. Dementia is observed in around 5–7% of adults over the age of 60. In a nationwide study in France based on data from hospital admissions, 38.9% of the cases of early-onset dementia (observed in adults under the age of 65) were related to alcohol use and an additional 17.6% had an alcohol use disorder. The study also reported that individuals with an alcohol use disorder were over 3 times more likely to have dementia later in life. 

Can Dementia Lead to Substance Abuse?

Although substance abuse can have neurotoxic effects resulting in dementia,

there is currently scant evidence suggesting a causal role of dementia in substance use disorders. This lack of data may be due to the debilitating cognitive and functional deficits of dementia that may prevent access to drugs. There is, however, evidence that individuals with dementia may be inappropriately prescribed drugs. Individuals with Alzheimer’s disease and other dementias often have comorbid disorders like hypertension, coronary heart disease and diabetes. These individuals also often show psychological symptoms such as depression, anxiety and sleep disorders. Interactions between medications prescribed for psychological symptoms and comorbid disorders may lead to adverse reactions. Studies suggest that many dementia patients are prescribed a higher number of drugs along with medications that cause adverse reactions. 

Alcohol is the most commonly abused substance by the elderly, followed by prescription drugs. There is a lack of scientific research on commonly abused substances by dementia patients, but abuse of substances like alcohol and prescription medications in dementia patients may occur as self-medication for their psychological symptoms. Certain subtypes of dementia like frontotemporal dementia, which leads to disinhibition of behavior and impulsive behavior, have been reported to lead to inappropriate behaviors, internet addiction, and drug and alcohol abuse.

Treating Dementia and Co-Occurring Disorders

Treatment of dementia and a co-occurring substance use disorder may be necessary for the best therapeutic outcome. Individuals living with dementia sometimes use alcohol and other substances as a form of self-medication for the psychological symptoms of depression and anxiety and other behavior-related problems. On the other hand, substance use disorders may worsen the already existing cognitive deficits in dementia patients.

If you or a loved one are living with a substance abuse disorder, The Recovery Village can help. The Recovery Village specializes in the treatment of addiction along with co-occurring mental health conditions. Call today to learn more about treatment options.