Obesity is a serious public health problem in all western societies.Nearly 60% of adults in the U.S. and 50% in Europe are classifiedas obese or overweight. Researchers usually measure overweightwith a test called body mass index (BMI). BMI factors in bothweight and height. A BMI between 25 and 29.9 is "overweight"and greater than or equal to 30 is "obese," according to theWorld Health Organization. Being overweight is a risk factorfor diabetes and high blood pressure. Both of these conditionscan cause damage leading to loss of brain tissue. Loss of braintissue has been linked to poor cognitive function. One way toevaluate for loss of brain tissue is to take a picture of thebrain using a test called computed tomography (CT) or magneticresonance imaging (MRI). It is possible to see whether thereis any loss of brain tissue in different parts of the brain.This is called "atrophy." Researchers are not sure what thereal relationship is between being overweight and loss of braintissue. It could be that being overweight "causes" diabetesand hypertension, which in turn, "cause" loss of brain tissue.It is also possible, however, that being overweight "causes"brain loss independent from these other conditions. More informationabout cognitive dysfunction and dementia can be found on thenext page.
In this issue of Neurology, Gustafson et al.1 report a studyof 290 Swedish women born between 1908 and 1922. This purposeof the study was to determine whether being overweight is arisk factor for brain atrophy on CT or cognitive dysfunction.All of these women had undergone four evaluations occurringevery 6 years, beginning in 1968. These evaluations includedgeneral health information and measurements of weight, height(to determine BMI), and blood pressure. In the 1992 exam, thesewomen also agreed to undergo cognitive testing and a CT scanof the brain.
Over the 24-year follow-up period, both BMI and cerebral atrophysteadily increased with age. Despite this, patients with a highBMI at each one of the four evaluations were much more likelyto have atrophy on the brain CT scans. High BMI remained animportant risk factor for brain atrophy in its own right evenwhen other factors that can lead to brain atrophy (diabetesand hypertension) were factored in. (See figures 1 and 2 forexamples of brain scans.)
Figure 2. Brain scan from a person with a loss of brain tissue. The dark, butterfly-shaped area in the center of the brain is spinal fluid. It is larger than it should be because the spinal fluid expands to fill up the space left by loss of brain tissue.
The study did not find that either being overweight or brainatrophy was associated with cognitive dysfunction. The testthat the researchers used to test for cognitive dysfunctionwas not very sensitive. This means that important, but subtleproblems with cognition could have been missed. More studiesneed to be done to address this question. It is important toremember that among all of the other adverse health effectsof obesity or being overweight, loss of brain tissue may alsobe one of them. If you suffer from obesity or are overweight,it is important to talk to your doctor about what you can doto lose weight and be healthier!
What is dementia?
Dementia is a decline in mental functions that generally includesshort and long-term memory, and is often associated with changesin language, logical thinking and personality. It persists overtime, but in some specific cases it may be reversible. It interfereswith job performance, relationships and eventually basic elementsof self-care. Dementia tends to occur late in life, affectingabout 1% at the age of 60, and increasing to over 35% by theage of 85.
Are all dementias the same?
No—there are several different types of dementia thatvary by location within the brain and have widely differentcauses. In the early stages, signs of the disorder may be quitedifferent and need early attention, because different typesof treatment may be possible. The most common form of dementiais Alzheimer disease. Other common varieties include the vasculardementias, which are associated with strokes. Vascular dementiashave various symptoms depending on whether the patient sufferslarge or small, single or multiple strokes, and what parts ofthe brain are injured. Vascular dementias are most common inpeople with high blood pressure and diabetes. Another type ofdementia that is becoming better recognized is called dementiawith Lewy bodies. In this form, there are problems with gaitand balance, fluctuations in alertness and mental functions,hallucinations and delusions, falls, and episodes of unresponsiveness.Other varieties of dementia include those that involve the frontallobes (the front part of the brain). In these dementias, personalitychanges, poor judgment, inappropriate behaviors, and lack ofgoal setting and planning are typical. Other forms of dementiaare associated with diseases such as HIV/AIDS, Parkinson disease,and various rare infectious diseases, including a variant ofMad Cow disease.
Which dementias may be reversible?
Less than 10% of dementias may be fully reversible, but theseshould always be considered. The most common are those thatinvolve thyroid disease and low vitamin B12 levels, which maybe detected with simple laboratory tests. Depression is commonin the elderly and often associated with dementia. Treatmentof depression may improve some signs of mental impairment. Previousinfection with syphilis may occasionally be associated withdementia and should be tested if there are specific risk factorsor evidence of prior infection. Another potentially reversiblecause of dementia is "normal-pressure hydrocephalus" which ischaracterized by problems with gait, urinary incontinence andmental decline. A surgical procedure may reverse symptoms iftreated early enough. Other diseases, infections, and even headinjury may be associated with cognitive impairment and may befound by blood tests or brain imaging studies (e.g., CT or MRIscans). Correction or treatment of these underlying causes maylead to improvement in mental function.
What are the warning signs?
Patients rarely seek medical help for their symptoms becausethey are often unaware that there is a problem. This lack ofinsight is a common feature of the early stages of dementia.Sometimes families do not act either because they think thebehaviors are a normal part of getting older. Problems withremembering recent events, such as whether or not a patientate breakfast or took his or her medications, may occur in theearly stages. Patients with early dementia may misplace personalbelongings and accuse others of "stealing" them; or they mayhave difficulty finding words or names. Changes in behaviormay also be common with increased irritability and defensiveness,especially when family members suggest that they may need medicalhelp. Lack of attention to personal hygiene and dressing, andloss of interest in previous activities or hobbies may be warningsigns. Behaviors that had previously been present may worsento become socially inappropriate and suggest that a medicalcheckup is needed.
What should you do if you suspect dementia in a loved one?
Early diagnosis is key. It is critical to seek medical attentionif you recognize or suspect symptoms of dementia. Routine laboratorytesting may detect reversible causes of dementia. You may bereferred to a doctor who specializes in dementia for furtherevaluation and treatment. Early treatments may help to slowthe progression of some of the progressive dementias, such asAlzheimer disease. There are also changes that can to made inthe patient’s environment as well as medications thatmay help treat some of the behavioral problems. The more thecaregivers can learn about the dementia process and how to manageit, the longer the patient may be able to remain at home. Supportsystems include adult day care programs, computer and telephonesupport groups, and other respite programs. Research effortsshould be supported to further the understanding, treatment,and prevention of dementias.
Gustafson D, Lissner L, Bengtsson C, Björkelund C, Skoog I. A 24-year follow-up of body mass index and cerebral atrophy. Neurology. 2004; 63: 1876–1881.[Abstract/Free Full Text]
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