Common medicines including cold and flu tablets, heartburn drugs and sleeping pills 'SHRINK the brain and slow down thinking'

Ingredients promethazine and diphenhydramine 'slowed brain function'

Block chemical acetylcholine involved in transmitting electrical impulses

Researchers said the drugs had an effect for a month after treatment  

A full list of implicated medications can be viewed at Ageing Brain Care 

Or scroll down for a full list of the medications listed in the study

By Colin Fernandez, Science Correspondent For The Daily Mail

Published: 10:00 EST, 18 April 2016 | Updated: 16:27 EST, 18 April 2016

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Common over-the-counter medicines should be avoided by older people as they have been linked to memory loss and problems in thinking, scientists have discovered.

Treatments for colds and flu, hay fever, allergy and heartburn tablets containing anti-cholinergic drugs had the effect for one month after treatment, a study found.

Effects associated with taking the drugs included having slower brain processing times and smaller brains overall.

Well known treatments including the heartburn medicine Zantac, Night Nurse Liquid containing Promethazine and the sleeping tablet Nytol, containing diphenhydramine, are included among drugs that may result in the effects, the research said.

Over the counter treatments for cold, flu, heartburn and sleeping tablets were found to block the chemical acetylcholine, which is involved in the tra nsmission of electrical impulses between nerve cells

The drugs block the chemical acetylcholine, which is involved in the transmission of electrical impulses between nerve cells.

The treatments are prescribed for a wide range of conditions, including Parkinson's disease, overactive bladder, chronic obstructive pulmonary disease, nausea and vomiting, sleeping problems, high blood pressure, depression and psychosis.

But the authors warn: 'Use of AC [anti-cholinergic] medication among older adults should likely be discouraged if alternative therapies are available.'

Previous studies have linked the drugs with cognitive impairment, increased risk of dementia and falls.

However, the new study by Indiana University School of Medicine, is the first to explore their impact on brain metabolism and atrophy through brain scans.

Dr Shannon Risacher, the university's assistant professor of radiology and imaging sciences, said: 'These findings provide us with a much better understanding of how this class of drugs may act upon the brain in ways that might raise the risk of cognitive impairment and dementia,'

'Given all the research evidence, physicians might want to consider alternatives to anticholinergic medications if available when working with their older patients.

'The impact of these drugs have been know about for over a decade, with a 2013 study finding drugs with a strong anticholinergic effect cause cognitive problems when taken continuously for as few as 60 days. Drugs with a weaker effect could cause impairment within 90 days.'

Many over the counter medicines have been linked to slower brain processing times and smaller brains

The new study involved 451 participants, 60 of whom were taking at least one medication with medium or high anticholinergic activity.

The participants were drawn from a national Alzheimer's research project - the Alzheimer's Disease Neuroimaging Initiative - and the Indiana Memory and Ageing Study.

To identify possible physical and physiological changes that could be associated with the reported effects, researchers assessed the results of memory and other cognitive tests, positron emission tests (PET) measuring brain metabolism, and magnetic resonance imaging (MRI) scans for brain structure.

Patients taking anticholinergic drugs performed worse than older adults not taking the drugs on short-ter m memory and some tests of executive function, which cover a range of activities such as verbal reasoning, planning, and problem solving.

Anticholinergic drug users also showed lower levels of glucose metabolism - a biomarker for brain activity - in both the overall brain and in the hippocampus, a region of the brain associated with memory and which has been identified as affected early by Alzheimer's disease.

The researchers also found significant links between brain structure revealed by the MRI scans and anticholinergic drug use, with the participants using anticholinergic drugs having reduced brain volume and larger ventricles, the cavities inside the brain.

Professor Risacher added: 'These findings might give us clues to the biological basis for the cognitive problems associated with anticholinergic drugs, but additional studies are needed if we are to truly understand the mec hanisms involved.'

The study was published in the journal JAMA Neurology.  

John Smith, Chief Executive of the Proprietary Association of Great Britain, which represents makers of over the counter medicines, said the medicines linked to the study were not intended to be used on a daily basis.

Anticholinergic medicines include some over-the-counter allergy and cold and flu products. However they are intended for short term relief of symptoms only 

He said: 'It is important to note that the JAMA study only involved people with a mean age of 73 in what the researchers conceded was a small sample. 

The study followed people who took medicines that were low, medium or high in anticholinergic activity, and concluded that the use of medication with medium or high anticholinergic activity should be discouraged in olde r adults if alternative therapies are available.

'However, due to the study limitations, the researchers propose that further and more advanced studies are needed.

'Anticholinergic medicines include some over-the-counter allergy and cold and flu products but these are intended for short term relief of symptoms and not for continuous use as in the research.

'If anyone has any concerns about their medicine, we would advise them to talk to their pharmacist. 

'There is a range of different allergy, cold and flu products on the market which contain different ingredients, many of which were not considered in this study, and a pharmacist will be able to recommend a suitable product.

'All over-the-counter medicines in the UK have been approved by the Medicines and Healthcare Products Regulatory Agency (MHRA) and are rigor ously assessed for safety and efficacy. 

'Once on the market, their safety is continually monitored in light of any emerging evidence.' 

FULL LIST OF IMPLICATED MEDICATIONS  DrugPrescribed for/Type of drug US brand nameUK brand name Other brand names    AlimemazineSedative, antihistamine  Zentiva Theralen    Alverine Gastrointestinal disorders  Spasmonal    Alprazolam Sedative, anxiety Xanax Xanax Niravam   Aripiprazole Antipsychotic Abilify Abilify Abilify Discmelt , Aristada   Asenapine SchizophreniaSaphris Sycrest    Atenolol Beta blocker, high blood pressure Tenormin Tenormin    Amantadine Antiviral, flu Symmetrel Symmetrel    Amitriptyline Antidepressant Elavil Elavil Vanatrip, Endep   Amoxapine Antidepressant Asendin Asendin    Atropine Treats heart rhythms, stomach and bowel problems    Sal-Tropine, Atreza   Bupropion Antidepressant, smoking cessation Wellbutrin Zyban    BelladonnaLeg, nerve pain and psychiatric disorders   Plant also known as deadly nightshade   Benztropine Parkinson's disease Cogentin     Brompheniramine Antihistamine Dimetapp     Captopril High blood pressure, heart failure Capoten Capoten    Cetirizine Antihistamine Zyrtec Zyrtec    Chlorthalidone Diuretic Diuril Hygroton    Cimetidine Stomach ulcer, gastroesophageal reflux disease (GERD) Tagamet Tagamet    Clidinium Peptic ulcers Librax  Quarzan   Clorazepate A nxiety, partial seizures, alcohol abuse disorder Tranxene     Codeine Opioid painkiller Contin Nurofen Plus, Solpadeine Max, Panadol Ultra    Colchicine Gout Colcrys Colchicine    Carbamazepine Anticonvulsant, seizures Tegretol Tegretol    Cyclobenzaprine Musculoskeletal pain, injury Flexeril  Amrix, Fexmid   Cyproheptadine Antihistamine Periactin Periactin    Carbinoxamine Antihistamine Histex  Carbihist   Chlorpheniramine Antihistamine Chlor-Trimeton Piriton    Chlorpromazine Anti-psychotic  Thorazine Thorazine    Clemastine Antihistamine Tavist Tavegil    Clomipramine Antidepressant Anafranil Anafranil    Clozapine Antipsychotic Clozaril Clozaril    Desloratadine Antihistamine Clarinex Clarinex    Diazepam Anxiety, alcohol abuse disorder, muscle spasm Valium Valium    Digoxin Heart failure Lanoxin Lanoxin    Dipyridamole Prevents blood clots Persantine Persantine    Diso pyramide Irregular heartbeat Norpace Norpace    Darifenacin Overactive bladder Enablex Enablex    Desipramine Antidepressant Norpramin Norpramin    Dicyclomine Irritable bowel syndrome Bentyl Merbentyl    Dimenhydrinate Anti-nausea Dramamine Arlevert    Diphenhydramine Antihistamine Benadryl Benadryl    Doxepin Depression, anxiety Sinequan Sinequan Deptran   Doxylamine Antihistamine Unisom Unisom    Fentanyl Opioid painkiller Duragesic Duragesic Actiq  Furosemide Heart failure, liver disease Lasix Lasix Frusol   Fluvoxamine Antidepressant, obsessive compulsive disorder Luvox Faverin    Fesoterodine Overactive bladder Toviaz Toviaz    Flavoxate Bladder pain, incontinence Urispas Urispas    Haloperidol Scizophrenia Haldol Haldol    Hydroxyzine Antihistamine Atarax Atarax Vistaril   Hyoscyamine Muscle spasms, stomach and intestinal disorders Anaspaz Anaspaz Levsin   Hydralazin e High blood pressure Apresoline Apresoline    Hydrocortisone Steroid, treats eczema, psoriasis Cortef Cortaid    Iloperidone Schizophrenia Fanapt Fanapt    Isosorbide Angina Isordil Isordil Ismo   Imipramine Antidepressant Tofranil Tofranil    Levocetirizine Antihistamine Xyzal Xyzal    Loperamide Diarrhea Immodium Immodium    Loratadine Antihistamine Claritin Claritin    Loxapine Schizophrenia Loxitane Xylac    Metoprolol Angina, high blood pressure Lopressor Lopressor Toprol   Morphine Opioid painkiller MS Contin MS Contin Avinza   Meperidine Opioid painkiller Demerol Demerol    Methotrimeprazine Anti-psychotic Levoprome Levoprome    Molindone Anti-psychotic Moban Moban    Meclizine Nausea, vomiting, dizziness Antivert Antivert    Methocarbamol Muscle relaxant  Robaxin Robaxin    Nifedipine High blood pressure, angina Procardia Adalat    Nefopam Painkiller  Nef ogesic Acupan    Nortriptyline Antidepressant Pamelor Pamelor    Oxcarbazepine Epilepsy, anti-convulsant Trileptal Trileptal    Paliperidone Anti-psychotic Invega Invega    Prednisone Anti-inflammatory Deltasone DeltasoneSterapred   Pimozide Anti-psychotic Orap Orap    Olanzapine Anti-psychotic Zyprexa Zyprexa    Orphenadrine Muscle relaxant Norflex Norflex    Oxybutynin Overactive bladder Ditropan Ditropan    Paroxetine Antidepressant Paxil Seroxat    Perphenazine Anti-psychotic Trilafon Fentazin    Promethazine Antihistamine Phenergan Phenergan    Propantheline Reduces stomach acid in patients with stomach ulcers Pro-Banthine Pro-Banthine    Propiverine Incontinence Detrunorm Detrunorm    Quinidine Heart rhythm disorders Quinaglute Quinaglute    Quetiapine Anti-psychotic Seroquel Seroquel    Ranitidine Stomach ulcers Zantac Zantac    Risperidone Anti-psychotic Risp erdal Risperdal    Scopolamine Nausea, vomiting, motion sickness Transderm Scop Transderm Scop    Solifenacin Overactive bladder Vesicare Vesicare    Theophylline Asthma, bronchitis, emphysema Theo-Dur Uniphyllin    Trazodone Antidepressant Desyrel Desyrel    Triamterene Diuretic Dyrenium Dyrenium    Thioridazine Anti-psychotic Mellaril Mellaril    Tolterodine Urinary incontinence Detrol Detrol    Trifluoperazine Anti-psychotic Stelazine Stelazine    Trihexyphenidyl Parkinson's disease Artane Trihexyphenidyl Genus    Trimipramine Depression Surmontil Surmontil    Trospium Overactive bladder Sanctura Sanctura    Venlafaxine Antidepressant Effexor Effexor    Warfarin Prevents formation of blood clots Coumadin Warfarin    Source: Aging Brain Care       
Source: Common medicines including cold and flu tablets, heartburn drugs and sleeping pills 'SHRINK the brain and slow down thinking'