it is the novel insight of the inventor that the effects of reduced insulin signaling on both lipid and protein metabolism can be useful in the treatment and prevention of protein accumulation in cells and in the treatment of diseases related thereto . as discussed herein , ketogenic diets can be useful in reducing neuron protein aggregation because ketogenic diets alter both lipid and protein metabolism . for example , low insulin signaling promotes protein degradation while inhibiting protein synthesis . it is the novel insight of the inventor that reduced insulin signaling can lead to the clearing of degradation sensitive proteins , such as amyloidic peptides and mutant huntington proteins . in addition , lower insulin signaling favors lipid metabolism over glucose use , and can lead to improved lipid homeostasis within neurons and improved function of lipid sensitive proteins such as app . together these mechanisms will offer treatment for protein aggregation diseases . contrary to the current belief that high fat diets increase risk for ad , the inventor has proposed that high carbohydrate ( hc ) diets are the primary cause of ad ( henderson , med hypotheses , 2004 , 62 : 689 - 700 ). this analysis is based on many factors including the known risk factors for sporadic ad , the most common form of the disease (& gt ; 95 % of cases ). sporadic ad is not linked with mutations in app or presenilin genes , instead it is associated with genetic risk factors . the best characterized risk factor for sporadic ad is possession of one or more of the ε4 alleles of the apolipoprotein e gene . demographic analysis of the ε4 allele has revealed that ε4 is rare in populations with long historical exposure to agriculture , suggesting consumption of hc diet may have selected against ε4 carriers ( corbo and scacchi , ann hum genet , 1999 , 63 ( pt 4 ): 301 - 10 ). furthermore , the apoe4 protein inhibits lipid metabolism in a manner similar to consumption of a high carbohydrate diet . therefore , it has been proposed that the inhibition of lipid metabolism by both hc diets and apoe4 is central to the development of ad ( henderson , med hypotheses , 2004 , 62 : 689 - 700 ). dietary intervention represents a relatively safe and readily available method to combat ad . yet , the key dietary links have previously remained unclear . much of the earlier work has focused on the role of high fat / cholesterol diets and their contribution to ad . previous studies had suggested that high fat / high cholesterol diets increased both the production and deposition of aβ in mouse models of ad , leading to the suggestion that diets rich in lipids were a factor in ad ( george , et al ., neurobiol dis , 2004 , 16 : 124 - 32 ; refolo , et al ., neurobiol dis , 2000 , 7 : 321 - 31 ; shie , et al ., neuroreport , 2002 , 13 : 455 - 9 ). however , these diets were not low carbohydrate diets . in the high cholesterol diets cholesterol was added to the diet without reduction in other components ( refolo ( 2000 ), supra ; george ( 2004 ), supra ). other high fat diets were fat rich diets that did not significantly reduce carbohydrate levels and hence were not low carbohydrate diets . ho et al used a diet of 60 % fat , 20 % carbohydrate , 20 % protein . this diet was sufficiently high in carbohydrate to cause the large increases in body weight ( ho ( 2004 ), supra ). in the present invention carbohydrate intake was very low (& lt ; 1 %) and resulted in weight loss . hence , the present invention describes that novel finding that it is not fats in the diet that cause increased aβ levels , but perhaps levels of carbohydrate or total calories . other studies have examined the role of carbohydrate content in the diet and aβ deposition . wang et al . examined transgenic ad mice under ad libitum feeding and a caloric restriction regime in which carbohydrate content and total calories were reduced 30 %. this treatment began when the animals were 3 months of age and the animals examined at 12 months of age . the low carbohydrate low calorie group had significantly lower plaque formation ( wang , et al ., faseb j , 2005 , 19 : 659 - 661 ). the present invention is distinct from wang et al . in many ways : 1 . wang et al . used a caloric restriction regime , where the total calories were limited in the experimental group . in the present invention animals had free access to food at all time and calories were not limited . 2 . wang et al did not use a ketogenic treatment , instead carbohydrate levels were still a significant portion of the diet and not low enough to promote ketosis . 3 . wang et al . administered caloric restriction for 9 months . typically long exposure to caloric restriction is necessary to see effects . in the present invention treatment was administered for only 38 days . in summary , it is the novel and surprising insight of inventor that a brief ( 38 day ) very low (& lt ; 1 %) carbohydrate , high fat treatment is sufficient to reduce aβ levels by 25 %. such results represent an unexpected efficiency in reduction of cellular protein aggregation . in us patent application us 2004 / 0058873 a1 , esmond et al ., teach that low carbohydrate diets can be used to treat alzheimer &# 39 ; s disease . paragraph [ 0031 ] states : a second method of the invention is directed to the treatment or prevention or alzheimer &# 39 ; s disease by the restriction of metabolizable carbohydrate in the diet . according to the invention , the amount of metabolizable carbohydrate is considered restricted if no more than about 55 grams are ingested per day . preferably , no more than about 30 grams of metabolizable carbohydrate are ingested . most preferably , no more than about 10 grams of metabolizable carbohydrate are ingested . the present invention differs from the teachings of 0058873 in the following ways . 1 . the present invention relates to the reduction of levels of aggregated proteins , while us 2004 / 0058873 relates to treatments for alzheimer &# 39 ; s disease by unclear mechanisms . the toxicity of aβ peptides remains an unanswered question in ad and it is not clear from esmond et al . that their treatment would reduce aβ levels . furthermore , it is not clear that reduction of aβ levels would necessarily treat ad . in contrast , the present invention is directed to reduction of protein aggregation in cells . 2 . the present invention represents clear advantages over us 2004 / 0058873 , which merely states that carbohydrates are to be lowered , but provides no means to measure the efficacy of the treatment . the present invention teaches that elevated serum ketone body levels are a marker for a ketogenic state that can be used to monitor compliance with the prescribed ketogenic treatment . 3 . furthermore , the present invention represents an improvement over us 2004 / 0058873 in that the present invention provides means to measure effectiveness of treatment . the present invention teaches that ketogenic treatments can reduce aβ levels and in vivo or in vitro measurements of aβ levels can be an effective means to measure ketogenic treatment efficacy . methods to detect levels of aβ in sera are well known to those skilled in the art . measuring aβ levels in vivo within the cns is also known to those skilled in the art ( nordberg , lancet neurol , 2004 , 3 : 519 - 27 ). detection of other aggregrated proteins is well known in the field . for example detection of polyglutamine inclusions is well documented ( yamamoto , et al ., cell , 2000 , 101 : 57 - 66 ). 4 . us 2004 / 0058873 also relates to treatment of ad with insulin sensitizing agents . paragraph [ 0033 ] states : the present invention also relates to a method improving mentation of a patient with alzheimer &# 39 ; s disease , comprising administration to said patient an effective amount of an agent which increases insulin sensitivity of the patient . in the present invention , administration of a high fat diet is well known to those skilled in the art to induce insulin resistance and not insulin sensitivity . insulin resistance also commonly occurs during starvation , a condition mimicked by ketogenic diet . under both of these conditions ( high fat diet and starvation ), tissues such as muscle and liver become resistant to the action of insulin and hence decrease their uptake of glucose . this is a mechanism to preserve glucose for central nervous system function . it also has many other outcomes . inducing insulin resistance inhibits insulin signaling which inhibits protein synthesis , while increasing protein degradation ( as previously discussed herein ). it is the novel insight of the inventor that these alterations in protein metabolism are advantageous to decrease levels of toxic proteins . hence , decreased insulin sensitivity , via a ketogenic treatment , will be the preferred mechanism to treat protein aggregation diseases . this is the opposite of what is taught in us 2004 / 00558873 . in one embodiment of the subject invention , the mammal is administered a low carbohydrate , low protein ketogenic diet that maintains the mammal in a state of ketosis . ketosis is defined as serum ketone body levels elevated above normal fasting values . such values will vary depending on both the species of mammal and individual within a species . in humans , normal fasting serum beta - hydroxybutyrate ( bhb ) range from 0 . 01 mm to 0 . 2 mm and can rise as high as 14 mm during prolonged starvation . therefore bhb levels above 0 . 3 mm for more than one hour can be considered to be ketosis or a ketogenic state in humans . in ad libitum fed mice , typical bhb levels range from 0 . 01 to 0 . 4 mm ( see example 1 , below ). induced ketone levels in mice range from 0 . 4 to as much as 10 mm . therefore , in mice , ketosis can be considered to represent serum bhb levels above 0 . 4 mm for longer than one hour . ketone bodies include acetoacetate , β - hydroxybutyrate and acetone . methods to measure serum and tissue ketone levels are well known to those skilled in the art . for a human , the subject invention would require that carbohydrate levels be restricted to less than twenty percent of total calories . for example , for an individual on a 2000 a day calorie diet , less than 400 calories a day could be derived from carbohydrate ( 1 gram of carbohydrate = 4 calories ); therefore , less 100 grams a day of carbohydrate would be consumed . more ideally , less than 50 grams a day , and even more preferred is less than 10 grams a day . variation in diet composition will be necessary to maintain said mammal in ketosis . for example , progressively more carbohydrate may have to be restricted over time to maintain ketosis . in another embodiment , agents that induce a ketogenic state are administered to a mammal in need thereof . a ketogenic state is defined as serum ketone body levels elevated above normal fasting values , but which are induced by non - dietary means . a ketogenic state would differ from ketosis in that it may be achieved by methods other than dietary intervention , such as administration of a compound or a physical training regime . for example , administration of agents that increase fatty acid oxidation may induce a ketogenic state even in the presence of abundant carbohydrates . such a state may prove beneficial in the treatment of protein aggregation diseases . in one preferred embodiment , a carbohydrate restricted diet is combined with an exercise program to decrease insulin signaling , improve fatty acid oxidation , and increase blood ketone levels . in another embodiment , a brief ketogenic treatment is administered to a mammal in need thereof . this treatment could be either induction of ketosis by dietary intervention or induction of ketogenic state as described above . such a treatment would be of limited duration , ranging from 1 day to 1 year , after which time said mammal would return to feeding ad libitum or discontinue treatments . macronutrient components of the ketogenic diet would be as described above , with precise profile depending on species and individual . in another preferred embodiment the success of a treatment for dementia is determined based on blood ketone levels . compounds or interventions to treat or prevent dementia will be assayed by their ability to induce elevated serum ketone body levels above baseline values . example 1 demonstrates that a ketogenic diet is successful in reducing the levels of aβ peptide in a transgenic mouse model of alzheimer &# 39 ; s disease . after 40 days of treatment , aβ levels were decreased 25 % without adverse consequences on cognitive performance . these results are surprising in that they run contrary to the current view linking high fat diets with alzheimer &# 39 ; s disease . the following examples are intended to illustrate but not limit the present invention . here we tested the effects of an extremely low carbohydrate / high fat ketogenic diet on a transgenic mouse model of ad , app / v7171 ( moechars , et al ., j biol chem , 1999 , 274 : 6483 - 92 ). sixteen app / v7171 mice were raised on standard chow for three months , then half were switched to a low carbohydrate / high fat chow , bio serv f3666 ( 6 : 1 ratio of fats : carbohydrate , protein ( bio - serv inc .)) and the remaining 8 mice remained on standard diet ( rm - klaver ). to measure the effectiveness of the chow , blood samples were taken weekly and examined for serum β - hydroxybutyrate ( bhb ) levels ( stanbio β - hydroxybutyrate kit , stanbio inc .). over the course of the experiment animals in the f3666 group had greatly elevated serum bhb levels compared to standard chow ( standard 0 . 323 ± 0 . 406 mm vs . f3666 3 . 976 ± 0 . 420 mm , p & lt ; 0 . 0001 ). after four weeks on the diet animals were tested for behavioral deficits using object recognition tests ( ort ). contrary to previous results ( zhao , et al ., pediatr res , 2004 , 55 : 498 - 506 ), there was no worsening of cognitive performance in the group fed high fat chow ( see fig1 c ). cognitive performance was measured using the novel object recognition test . this test was performed after 38 days of treatment and three days before sacrifice . the protocol used followed the method as described by dewachter et al . ( dewachter , et al ., j neurosci , 2002 , 22 : 3445 - 53 ). mice were familiarized for one hour to a plexiglas open - field box ( 52 × 52 × 40 cm ) with black vertical walls and a translucent floor , dimly illuminated by a lamp placed underneath the box . the next day the animals were placed in the same box and submitted to a 10 minutes acquisition trial . during this trial mice were placed individually in the open field in the presence of 2 × object a ( orange barrel or green cube , similar sized of ± 4 cm ), and the duration ( time aa ) and the frequency ( freq aa ) exploring object a ( when the animals snout was directed towards the object at a distance of & lt ; 1 cm and the mice were actively sniffing in the direction of the object ) was recorded by a computerized system ( ethovision , noldus information technology , wageningen , the netherlands ). during a 10 minutes retention trial ( second trial ) performed 3 hours later , a novel object ( object b , green cube or orange tun ) was placed together with the familiar object ( object a ) into the open field . ( freq a and freq b and time a and time b , respectively ). the recognition index ( r1 ), defined as the ratio of the duration in which the novel object was explored over the duration in which both objects were explored [ time b /( time a + time b )× 100 ], was used to measure non - spatial memory . the duration and frequency object a was explored during the acquisition trial ( time aa and freq aa ) was used to measure curiosity . mice that do not distinguish between an old object and a new one , have a recognition index of 50 . mice that recognize the old object , will preferably explore the novel object and hence the recognition index becomes & gt ; 50 . mice that exclusively explore the novel object have a recognition index of 100 . after 38 days of treatment there was no difference in any ort scores ( fig1 c ). at the conclusion of the experiment both serum and brain bhb measures were obtained . consistent with earlier results , serum bhb levels were higher in f3666 fed animals ( standard 0 . 12 ± 0 . 618 mm vs . f3666 3 . 26 ± 0 . 667 mm , p = 0 . 00541 ). contrary to early reports of high fat diets increasing aβ levels in the brain , levels of both soluble aβ 40 ( standard 1 . 725 ± 0 . 104 vs f3666 1 . 279 ± 0 . 112 ng / g protein , p value = 0 . 0140 ) and aβ 42 ( standard 0 . 879 ± 0 . 042 vs f3666 0 . 706 ± 0 . 046 ng / g protein , p value = 0 . 016 ) were found to be significantly lower in the brains of the f3666 fed group , while overall protein levels as measure as mg / ml of brain homogenate did not differ ( standard 0 . 562 ± 0 . 035 vs . f3666 0 . 509 ± 0 . 017 , p = 0 . 213 ). there was no difference in the mean ratio of aβ 42 / 40 between groups ( standard 0 . 517 ± 0 . 024 vs . f3666 0 . 556 ± 0 . 026 , p = 0 . 2872 ) suggesting a general lowering of aβ species but not specific to either form . a cell - based assay is used to show that ketogenic conditions , low glucose and low growth factor levels , can decrease toxic protein levels . differentiated inducible pc12 cells expressing a polyq green fluorescent protein ( polyq :: gfp ) transgene are tested for visible polyq :: gfp protein inclusion formation under normal growth conditions and ketogenic conditions . cells are plated on 10 - cm plates using standard tissue culture medium including abundant glucose and growth factors . examples of such media include dulbecco &# 39 ; s modified eagle medium ( d - mem ) ( 1 ×) liquid ( high glucose ); such media contains 4500 g / l ( 25 mm ) glucose and are supplemented with fetal calf serum rich in growth factors (& gt ; 1 nm insulin / igf - 1 ). cells are allowed to express the polyq :: gfp protein and to form inclusions . after inclusions have formed , half the plates are maintained in normal media , while half are exposed to ketogenic media ( low glucose and low growth factor ). examples of ketogenic media include minimum essential medium ( mem ) liquid ( life technologies inc . ); such media contains 1000 mg / l ( 5 . 56 mm ) glucose and does not contain growth factors . thus media containing less than 5 . 56 mm glucose can be considered low glucose and ketogenic . growth factors , such as insulin , are known to inhibit the activity of ketogenic enzymes . for example , insulin levels greater than 1 nm were found to inhibit the expression of key enzymes in ketogenesis ( nadal , et al ., biochem j , 2002 , 366 : 289 - 97 ). thus ketogenic media can be considered media in which growth factors , such as insulin are below 1 nm . the cells are grown overnight in the differential media and aggregation is calculated by using fluorescent microscopy . it is expected that ketogenic media will be found to inhibit aggregation and reduce levels of polyq :: gfp . mice carrying a mutant polyq containing transgene are used to show that a brief ketogenic diet treatment reduces polyglutamine pathogenesis in vivo . mice that carry a transgene expressing exon 1 of the huntingin protein with a polyq coding region develop progressive motor dysfunction , neuronal inclusions , and neuropathology typical of hd . such transgenic animals are raised on normal , high carbohydrate , rodent chow until the age they typically begin to show signs of motor dysfunction . at this time , half of the mice are switched to a ketogenic chow ( as described in example 1 ) while half are left on normal chow . mice in each group are maintained for 30 days on their respective diets . at the end of the treatment , mice in each group are tested for motor function , using a rotating rod . after completion of motor testing , the brains of the animals are examined for the presence and extent of neuronal inclusions . mice fed ketogenic chow are expected to perform for longer times on the motor rod , reflecting significant rescue of motor function , and show decreased amount and extent of polyq containing aggregates .